UsdLux module — pxr-usd-api 105.1 documentation

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UsdLux module

Summary: The UsdLux module provides a representation for lights and related components that are common to many graphics environments.

Classes:

BoundableLightBase Base class for intrinsic lights that are boundable.

CylinderLight Light emitted outward from a cylinder.

DiskLight Light emitted from one side of a circular disk.

DistantLight Light emitted from a distant source along the -Z axis.

DomeLight Light emitted inward from a distant external environment, such as a sky or IBL light probe.

GeometryLight Deprecated

LightAPI API schema that imparts the quality of being a light onto a prim.

LightFilter A light filter modifies the effect of a light.

LightListAPI API schema to support discovery and publishing of lights in a scene.

ListAPI Deprecated

MeshLightAPI This is the preferred API schema to apply to Mesh type prims when adding light behaviors to a mesh.

NonboundableLightBase Base class for intrinsic lights that are not boundable.

PluginLight Light that provides properties that allow it to identify an external SdrShadingNode definition, through UsdShadeNodeDefAPI, that can be provided to render delegates without the need to provide a schema definition for the light's type.

PluginLightFilter Light filter that provides properties that allow it to identify an external SdrShadingNode definition, through UsdShadeNodeDefAPI, that can be provided to render delegates without the need to provide a schema definition for the light filter's type.

PortalLight A rectangular portal in the local XY plane that guides sampling of a dome light.

RectLight Light emitted from one side of a rectangle.

ShadowAPI Controls to refine a light's shadow behavior.

ShapingAPI Controls for shaping a light's emission.

SphereLight Light emitted outward from a sphere.

Tokens

VolumeLightAPI This is the preferred API schema to apply to Volume type prims when adding light behaviors to a volume.

class pxr.UsdLux.BoundableLightBase Base class for intrinsic lights that are boundable. The primary purpose of this class is to provide a direct API to the functions provided by LightAPI for concrete derived light types. Methods:

CreateColorAttr(defaultValue, writeSparsely) See UsdLuxLightAPI::CreateColorAttr() .

CreateColorTemperatureAttr(defaultValue, ...) See UsdLuxLightAPI::CreateColorTemperatureAttr() .

CreateDiffuseAttr(defaultValue, writeSparsely) See UsdLuxLightAPI::CreateDiffuseAttr() .

CreateEnableColorTemperatureAttr(...) See UsdLuxLightAPI::CreateEnableColorTemperatureAttr() .

CreateExposureAttr(defaultValue, writeSparsely) See UsdLuxLightAPI::CreateExposureAttr() .

CreateFiltersRel() See UsdLuxLightAPI::CreateFiltersRel() .

CreateIntensityAttr(defaultValue, writeSparsely) See UsdLuxLightAPI::CreateIntensityAttr() .

CreateNormalizeAttr(defaultValue, writeSparsely) See UsdLuxLightAPI::CreateNormalizeAttr() .

CreateSpecularAttr(defaultValue, writeSparsely) See UsdLuxLightAPI::CreateSpecularAttr() .

Get classmethod Get(stage, path) -> BoundableLightBase

GetColorAttr() See UsdLuxLightAPI::GetColorAttr() .

GetColorTemperatureAttr() See UsdLuxLightAPI::GetColorTemperatureAttr() .

GetDiffuseAttr() See UsdLuxLightAPI::GetDiffuseAttr() .

GetEnableColorTemperatureAttr() See UsdLuxLightAPI::GetEnableColorTemperatureAttr() .

GetExposureAttr() See UsdLuxLightAPI::GetExposureAttr() .

GetFiltersRel() See UsdLuxLightAPI::GetFiltersRel() .

GetIntensityAttr() See UsdLuxLightAPI::GetIntensityAttr() .

GetNormalizeAttr() See UsdLuxLightAPI::GetNormalizeAttr() .

GetSchemaAttributeNames classmethod GetSchemaAttributeNames(includeInherited) -> list[TfToken]

GetSpecularAttr() See UsdLuxLightAPI::GetSpecularAttr() .

LightAPI() Contructs and returns a UsdLuxLightAPI object for this light.

CreateColorAttr(defaultValue, writeSparsely) → Attribute See UsdLuxLightAPI::CreateColorAttr() .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateColorTemperatureAttr(defaultValue, writeSparsely) → Attribute See UsdLuxLightAPI::CreateColorTemperatureAttr() .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateDiffuseAttr(defaultValue, writeSparsely) → Attribute See UsdLuxLightAPI::CreateDiffuseAttr() .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateEnableColorTemperatureAttr(defaultValue, writeSparsely) → Attribute See UsdLuxLightAPI::CreateEnableColorTemperatureAttr() .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateExposureAttr(defaultValue, writeSparsely) → Attribute See UsdLuxLightAPI::CreateExposureAttr() .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateFiltersRel() → Relationship See UsdLuxLightAPI::CreateFiltersRel() .

CreateIntensityAttr(defaultValue, writeSparsely) → Attribute See UsdLuxLightAPI::CreateIntensityAttr() .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateNormalizeAttr(defaultValue, writeSparsely) → Attribute See UsdLuxLightAPI::CreateNormalizeAttr() .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateSpecularAttr(defaultValue, writeSparsely) → Attribute See UsdLuxLightAPI::CreateSpecularAttr() .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

static Get() classmethod Get(stage, path) -> BoundableLightBase Return a UsdLuxBoundableLightBase holding the prim adhering to this schema at path on stage . If no prim exists at path on stage , or if the prim at that path does not adhere to this schema, return an invalid schema object. This is shorthand for the following: UsdLuxBoundableLightBase(stage->GetPrimAtPath(path));

Parameters

stage (Stage) – path (Path) –

GetColorAttr() → Attribute See UsdLuxLightAPI::GetColorAttr() .

GetColorTemperatureAttr() → Attribute See UsdLuxLightAPI::GetColorTemperatureAttr() .

GetDiffuseAttr() → Attribute See UsdLuxLightAPI::GetDiffuseAttr() .

GetEnableColorTemperatureAttr() → Attribute See UsdLuxLightAPI::GetEnableColorTemperatureAttr() .

GetExposureAttr() → Attribute See UsdLuxLightAPI::GetExposureAttr() .

GetFiltersRel() → Relationship See UsdLuxLightAPI::GetFiltersRel() .

GetIntensityAttr() → Attribute See UsdLuxLightAPI::GetIntensityAttr() .

GetNormalizeAttr() → Attribute See UsdLuxLightAPI::GetNormalizeAttr() .

static GetSchemaAttributeNames() classmethod GetSchemaAttributeNames(includeInherited) -> list[TfToken] Return a vector of names of all pre-declared attributes for this schema class and all its ancestor classes. Does not include attributes that may be authored by custom/extended methods of the schemas involved.

Parameters includeInherited (bool) –

GetSpecularAttr() → Attribute See UsdLuxLightAPI::GetSpecularAttr() .

LightAPI() → LightAPI Contructs and returns a UsdLuxLightAPI object for this light.

class pxr.UsdLux.CylinderLight Light emitted outward from a cylinder. The cylinder is centered at the origin and has its major axis on the X axis. The cylinder does not emit light from the flat end-caps. Methods:

CreateLengthAttr(defaultValue, writeSparsely) See GetLengthAttr() , and also Create vs Get Property Methods for when to use Get vs Create.

CreateRadiusAttr(defaultValue, writeSparsely) See GetRadiusAttr() , and also Create vs Get Property Methods for when to use Get vs Create.

CreateTreatAsLineAttr(defaultValue, ...) See GetTreatAsLineAttr() , and also Create vs Get Property Methods for when to use Get vs Create.

Define classmethod Define(stage, path) -> CylinderLight

Get classmethod Get(stage, path) -> CylinderLight

GetLengthAttr() Width of the rectangle, in the local X axis.

GetRadiusAttr() Radius of the cylinder.

GetSchemaAttributeNames classmethod GetSchemaAttributeNames(includeInherited) -> list[TfToken]

GetTreatAsLineAttr() A hint that this light can be treated as a'line'light (effectively, a zero-radius cylinder) by renderers that benefit from non-area lighting.

CreateLengthAttr(defaultValue, writeSparsely) → Attribute See GetLengthAttr() , and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateRadiusAttr(defaultValue, writeSparsely) → Attribute See GetRadiusAttr() , and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateTreatAsLineAttr(defaultValue, writeSparsely) → Attribute See GetTreatAsLineAttr() , and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

static Define() classmethod Define(stage, path) -> CylinderLight Attempt to ensure a UsdPrim adhering to this schema at path is defined (according to UsdPrim::IsDefined() ) on this stage. If a prim adhering to this schema at path is already defined on this stage, return that prim. Otherwise author an SdfPrimSpec with specifier == SdfSpecifierDef and this schema’s prim type name for the prim at path at the current EditTarget. Author SdfPrimSpec s with specifier == SdfSpecifierDef and empty typeName at the current EditTarget for any nonexistent, or existing but not Defined ancestors. The given path must be an absolute prim path that does not contain any variant selections. If it is impossible to author any of the necessary PrimSpecs, (for example, in case path cannot map to the current UsdEditTarget ‘s namespace) issue an error and return an invalid UsdPrim. Note that this method may return a defined prim whose typeName does not specify this schema class, in case a stronger typeName opinion overrides the opinion at the current EditTarget.

Parameters

stage (Stage) – path (Path) –

static Get() classmethod Get(stage, path) -> CylinderLight Return a UsdLuxCylinderLight holding the prim adhering to this schema at path on stage . If no prim exists at path on stage , or if the prim at that path does not adhere to this schema, return an invalid schema object. This is shorthand for the following: UsdLuxCylinderLight(stage->GetPrimAtPath(path));

Parameters

stage (Stage) – path (Path) –

GetLengthAttr() → Attribute Width of the rectangle, in the local X axis. Declaration float inputs:length = 1 C++ Type float Usd Type SdfValueTypeNames->Float

GetRadiusAttr() → Attribute Radius of the cylinder. Declaration float inputs:radius = 0.5 C++ Type float Usd Type SdfValueTypeNames->Float

Parameters includeInherited (bool) –

GetTreatAsLineAttr() → Attribute A hint that this light can be treated as a’line’light (effectively, a zero-radius cylinder) by renderers that benefit from non-area lighting. Renderers that only support area lights can disregard this. Declaration bool treatAsLine = 0 C++ Type bool Usd Type SdfValueTypeNames->Bool

class pxr.UsdLux.DiskLight Light emitted from one side of a circular disk. The disk is centered in the XY plane and emits light along the -Z axis. Methods:

CreateRadiusAttr(defaultValue, writeSparsely) See GetRadiusAttr() , and also Create vs Get Property Methods for when to use Get vs Create.

Define classmethod Define(stage, path) -> DiskLight

Get classmethod Get(stage, path) -> DiskLight

GetRadiusAttr() Radius of the disk.

GetSchemaAttributeNames classmethod GetSchemaAttributeNames(includeInherited) -> list[TfToken]

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

static Define() classmethod Define(stage, path) -> DiskLight Attempt to ensure a UsdPrim adhering to this schema at path is defined (according to UsdPrim::IsDefined() ) on this stage. If a prim adhering to this schema at path is already defined on this stage, return that prim. Otherwise author an SdfPrimSpec with specifier == SdfSpecifierDef and this schema’s prim type name for the prim at path at the current EditTarget. Author SdfPrimSpec s with specifier == SdfSpecifierDef and empty typeName at the current EditTarget for any nonexistent, or existing but not Defined ancestors. The given path must be an absolute prim path that does not contain any variant selections. If it is impossible to author any of the necessary PrimSpecs, (for example, in case path cannot map to the current UsdEditTarget ‘s namespace) issue an error and return an invalid UsdPrim. Note that this method may return a defined prim whose typeName does not specify this schema class, in case a stronger typeName opinion overrides the opinion at the current EditTarget.

Parameters

stage (Stage) – path (Path) –

static Get() classmethod Get(stage, path) -> DiskLight Return a UsdLuxDiskLight holding the prim adhering to this schema at path on stage . If no prim exists at path on stage , or if the prim at that path does not adhere to this schema, return an invalid schema object. This is shorthand for the following: UsdLuxDiskLight(stage->GetPrimAtPath(path));

Parameters

stage (Stage) – path (Path) –

GetRadiusAttr() → Attribute Radius of the disk. Declaration float inputs:radius = 0.5 C++ Type float Usd Type SdfValueTypeNames->Float

Parameters includeInherited (bool) –

class pxr.UsdLux.DistantLight Light emitted from a distant source along the -Z axis. Also known as a directional light. Methods:

CreateAngleAttr(defaultValue, writeSparsely) See GetAngleAttr() , and also Create vs Get Property Methods for when to use Get vs Create.

Define classmethod Define(stage, path) -> DistantLight

Get classmethod Get(stage, path) -> DistantLight

GetAngleAttr() Angular size of the light in degrees.

GetSchemaAttributeNames classmethod GetSchemaAttributeNames(includeInherited) -> list[TfToken]

CreateAngleAttr(defaultValue, writeSparsely) → Attribute See GetAngleAttr() , and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

static Define() classmethod Define(stage, path) -> DistantLight Attempt to ensure a UsdPrim adhering to this schema at path is defined (according to UsdPrim::IsDefined() ) on this stage. If a prim adhering to this schema at path is already defined on this stage, return that prim. Otherwise author an SdfPrimSpec with specifier == SdfSpecifierDef and this schema’s prim type name for the prim at path at the current EditTarget. Author SdfPrimSpec s with specifier == SdfSpecifierDef and empty typeName at the current EditTarget for any nonexistent, or existing but not Defined ancestors. The given path must be an absolute prim path that does not contain any variant selections. If it is impossible to author any of the necessary PrimSpecs, (for example, in case path cannot map to the current UsdEditTarget ‘s namespace) issue an error and return an invalid UsdPrim. Note that this method may return a defined prim whose typeName does not specify this schema class, in case a stronger typeName opinion overrides the opinion at the current EditTarget.

Parameters

stage (Stage) – path (Path) –

static Get() classmethod Get(stage, path) -> DistantLight Return a UsdLuxDistantLight holding the prim adhering to this schema at path on stage . If no prim exists at path on stage , or if the prim at that path does not adhere to this schema, return an invalid schema object. This is shorthand for the following: UsdLuxDistantLight(stage->GetPrimAtPath(path));

Parameters

stage (Stage) – path (Path) –

GetAngleAttr() → Attribute Angular size of the light in degrees. As an example, the Sun is approximately 0.53 degrees as seen from Earth. Higher values broaden the light and therefore soften shadow edges. Declaration float inputs:angle = 0.53 C++ Type float Usd Type SdfValueTypeNames->Float

Parameters includeInherited (bool) –

class pxr.UsdLux.DomeLight Light emitted inward from a distant external environment, such as a sky or IBL light probe. The orientation of a dome light with a latlong texture is expected to match the OpenEXR specification for latlong environment maps. From the OpenEXR documentation: Latitude-Longitude Map: The environment is projected onto the image using polar coordinates (latitude and longitude). A pixel’s x coordinate corresponds to its longitude, and the y coordinate corresponds to its latitude. Pixel (dataWindow.min.x, dataWindow.min.y) has latitude +pi/2 and longitude +pi; pixel (dataWindow.max.x, dataWindow.max.y) has latitude -pi/2 and longitude -pi. In 3D space, latitudes -pi/2 and +pi/2 correspond to the negative and positive y direction. Latitude 0, longitude 0 points into positive z direction; and latitude 0, longitude pi/2 points into positive x direction. The size of the data window should be 2*N by N pixels (width by height), For any described attribute Fallback Value or Allowed Values below that are text/tokens, the actual token is published and defined in UsdLuxTokens. So to set an attribute to the value”rightHanded”, use UsdLuxTokens->rightHanded as the value. Methods:

CreateGuideRadiusAttr(defaultValue, ...) See GetGuideRadiusAttr() , and also Create vs Get Property Methods for when to use Get vs Create.

CreatePortalsRel() See GetPortalsRel() , and also Create vs Get Property Methods for when to use Get vs Create.

CreateTextureFileAttr(defaultValue, ...) See GetTextureFileAttr() , and also Create vs Get Property Methods for when to use Get vs Create.

CreateTextureFormatAttr(defaultValue, ...) See GetTextureFormatAttr() , and also Create vs Get Property Methods for when to use Get vs Create.

Define classmethod Define(stage, path) -> DomeLight

Get classmethod Get(stage, path) -> DomeLight

GetGuideRadiusAttr() The radius of guide geometry to use to visualize the dome light.

GetPortalsRel() Optional portals to guide light sampling.

GetSchemaAttributeNames classmethod GetSchemaAttributeNames(includeInherited) -> list[TfToken]

GetTextureFileAttr() A color texture to use on the dome, such as an HDR (high dynamic range) texture intended for IBL (image based lighting).

GetTextureFormatAttr() Specifies the parameterization of the color map file.

OrientToStageUpAxis() Adds a transformation op, if neeeded, to orient the dome to align with the stage's up axis.

CreateGuideRadiusAttr(defaultValue, writeSparsely) → Attribute See GetGuideRadiusAttr() , and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreatePortalsRel() → Relationship See GetPortalsRel() , and also Create vs Get Property Methods for when to use Get vs Create.

CreateTextureFileAttr(defaultValue, writeSparsely) → Attribute See GetTextureFileAttr() , and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateTextureFormatAttr(defaultValue, writeSparsely) → Attribute See GetTextureFormatAttr() , and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

static Define() classmethod Define(stage, path) -> DomeLight Attempt to ensure a UsdPrim adhering to this schema at path is defined (according to UsdPrim::IsDefined() ) on this stage. If a prim adhering to this schema at path is already defined on this stage, return that prim. Otherwise author an SdfPrimSpec with specifier == SdfSpecifierDef and this schema’s prim type name for the prim at path at the current EditTarget. Author SdfPrimSpec s with specifier == SdfSpecifierDef and empty typeName at the current EditTarget for any nonexistent, or existing but not Defined ancestors. The given path must be an absolute prim path that does not contain any variant selections. If it is impossible to author any of the necessary PrimSpecs, (for example, in case path cannot map to the current UsdEditTarget ‘s namespace) issue an error and return an invalid UsdPrim. Note that this method may return a defined prim whose typeName does not specify this schema class, in case a stronger typeName opinion overrides the opinion at the current EditTarget.

Parameters

stage (Stage) – path (Path) –

static Get() classmethod Get(stage, path) -> DomeLight Return a UsdLuxDomeLight holding the prim adhering to this schema at path on stage . If no prim exists at path on stage , or if the prim at that path does not adhere to this schema, return an invalid schema object. This is shorthand for the following: UsdLuxDomeLight(stage->GetPrimAtPath(path));

Parameters

stage (Stage) – path (Path) –

GetGuideRadiusAttr() → Attribute The radius of guide geometry to use to visualize the dome light. The default is 1 km for scenes whose metersPerUnit is the USD default of 0.01 (i.e., 1 world unit is 1 cm). Declaration float guideRadius = 100000 C++ Type float Usd Type SdfValueTypeNames->Float

GetPortalsRel() → Relationship Optional portals to guide light sampling.

Parameters includeInherited (bool) –

GetTextureFileAttr() → Attribute A color texture to use on the dome, such as an HDR (high dynamic range) texture intended for IBL (image based lighting). Declaration asset inputs:texture:file C++ Type SdfAssetPath Usd Type SdfValueTypeNames->Asset

GetTextureFormatAttr() → Attribute Specifies the parameterization of the color map file. Valid values are:

automatic: Tries to determine the layout from the file itself. For example, Renderman texture files embed an explicit parameterization. latlong: Latitude as X, longitude as Y. mirroredBall: An image of the environment reflected in a sphere, using an implicitly orthogonal projection. angular: Similar to mirroredBall but the radial dimension is mapped linearly to the angle, providing better sampling at the edges. cubeMapVerticalCross: A cube map with faces laid out as a vertical cross.

Declaration token inputs:texture:format ="automatic" C++ Type TfToken Usd Type SdfValueTypeNames->Token Allowed Values automatic, latlong, mirroredBall, angular, cubeMapVerticalCross

OrientToStageUpAxis() → None Adds a transformation op, if neeeded, to orient the dome to align with the stage’s up axis. Uses UsdLuxTokens->orientToStageUpAxis as the op suffix. If an op with this suffix already exists, this method assumes it is already applying the proper correction and does nothing further. If no op is required to match the stage’s up axis, no op will be created. UsdGeomXformOp UsdGeomGetStageUpAxis

class pxr.UsdLux.GeometryLight Deprecated Light emitted outward from a geometric prim (UsdGeomGprim), which is typically a mesh. Methods:

CreateGeometryRel() See GetGeometryRel() , and also Create vs Get Property Methods for when to use Get vs Create.

Define classmethod Define(stage, path) -> GeometryLight

Get classmethod Get(stage, path) -> GeometryLight

GetGeometryRel() Relationship to the geometry to use as the light source.

GetSchemaAttributeNames classmethod GetSchemaAttributeNames(includeInherited) -> list[TfToken]

CreateGeometryRel() → Relationship See GetGeometryRel() , and also Create vs Get Property Methods for when to use Get vs Create.

static Define() classmethod Define(stage, path) -> GeometryLight Attempt to ensure a UsdPrim adhering to this schema at path is defined (according to UsdPrim::IsDefined() ) on this stage. If a prim adhering to this schema at path is already defined on this stage, return that prim. Otherwise author an SdfPrimSpec with specifier == SdfSpecifierDef and this schema’s prim type name for the prim at path at the current EditTarget. Author SdfPrimSpec s with specifier == SdfSpecifierDef and empty typeName at the current EditTarget for any nonexistent, or existing but not Defined ancestors. The given path must be an absolute prim path that does not contain any variant selections. If it is impossible to author any of the necessary PrimSpecs, (for example, in case path cannot map to the current UsdEditTarget ‘s namespace) issue an error and return an invalid UsdPrim. Note that this method may return a defined prim whose typeName does not specify this schema class, in case a stronger typeName opinion overrides the opinion at the current EditTarget.

Parameters

stage (Stage) – path (Path) –

static Get() classmethod Get(stage, path) -> GeometryLight Return a UsdLuxGeometryLight holding the prim adhering to this schema at path on stage . If no prim exists at path on stage , or if the prim at that path does not adhere to this schema, return an invalid schema object. This is shorthand for the following: UsdLuxGeometryLight(stage->GetPrimAtPath(path));

Parameters

stage (Stage) – path (Path) –

GetGeometryRel() → Relationship Relationship to the geometry to use as the light source.

Parameters includeInherited (bool) –

class pxr.UsdLux.LightAPI API schema that imparts the quality of being a light onto a prim. A light is any prim that has this schema applied to it. This is true regardless of whether LightAPI is included as a built-in API of the prim type (e.g. RectLight or DistantLight) or is applied directly to a Gprim that should be treated as a light. Linking Lights can be linked to geometry. Linking controls which geometry a light illuminates, and which geometry casts shadows from the light. Linking is specified as collections (UsdCollectionAPI) which can be accessed via GetLightLinkCollection() and GetShadowLinkCollection(). Note that these collections have their includeRoot set to true, so that lights will illuminate and cast shadows from all objects by default. To illuminate only a specific set of objects, there are two options. One option is to modify the collection paths to explicitly exclude everything else, assuming it is known; the other option is to set includeRoot to false and explicitly include the desired objects. These are complementary approaches that may each be preferable depending on the scenario and how to best express the intent of the light setup. For any described attribute Fallback Value or Allowed Values below that are text/tokens, the actual token is published and defined in UsdLuxTokens. So to set an attribute to the value”rightHanded”, use UsdLuxTokens->rightHanded as the value. Methods:

Apply classmethod Apply(prim) -> LightAPI

CanApply classmethod CanApply(prim, whyNot) -> bool

ConnectableAPI() Contructs and returns a UsdShadeConnectableAPI object with this light.

CreateColorAttr(defaultValue, writeSparsely) See GetColorAttr() , and also Create vs Get Property Methods for when to use Get vs Create.

CreateColorTemperatureAttr(defaultValue, ...) See GetColorTemperatureAttr() , and also Create vs Get Property Methods for when to use Get vs Create.

CreateDiffuseAttr(defaultValue, writeSparsely) See GetDiffuseAttr() , and also Create vs Get Property Methods for when to use Get vs Create.

CreateEnableColorTemperatureAttr(...) See GetEnableColorTemperatureAttr() , and also Create vs Get Property Methods for when to use Get vs Create.

CreateExposureAttr(defaultValue, writeSparsely) See GetExposureAttr() , and also Create vs Get Property Methods for when to use Get vs Create.

CreateFiltersRel() See GetFiltersRel() , and also Create vs Get Property Methods for when to use Get vs Create.

CreateInput(name, typeName) Create an input which can either have a value or can be connected.

CreateIntensityAttr(defaultValue, writeSparsely) See GetIntensityAttr() , and also Create vs Get Property Methods for when to use Get vs Create.

CreateMaterialSyncModeAttr(defaultValue, ...) See GetMaterialSyncModeAttr() , and also Create vs Get Property Methods for when to use Get vs Create.

CreateNormalizeAttr(defaultValue, writeSparsely) See GetNormalizeAttr() , and also Create vs Get Property Methods for when to use Get vs Create.

CreateOutput(name, typeName) Create an output which can either have a value or can be connected.

CreateShaderIdAttr(defaultValue, writeSparsely) See GetShaderIdAttr() , and also Create vs Get Property Methods for when to use Get vs Create.

CreateShaderIdAttrForRenderContext(...) Creates the shader ID attribute for the given renderContext .

CreateSpecularAttr(defaultValue, writeSparsely) See GetSpecularAttr() , and also Create vs Get Property Methods for when to use Get vs Create.

Get classmethod Get(stage, path) -> LightAPI

GetColorAttr() The color of emitted light, in energy-linear terms.

GetColorTemperatureAttr() Color temperature, in degrees Kelvin, representing the white point.

GetDiffuseAttr() A multiplier for the effect of this light on the diffuse response of materials.

GetEnableColorTemperatureAttr() Enables using colorTemperature.

GetExposureAttr() Scales the power of the light exponentially as a power of 2 (similar to an F-stop control over exposure).

GetFiltersRel() Relationship to the light filters that apply to this light.

GetInput(name) Return the requested input if it exists.

GetInputs(onlyAuthored) Inputs are represented by attributes in the"inputs:"namespace.

GetIntensityAttr() Scales the power of the light linearly.

GetLightLinkCollectionAPI() Return the UsdCollectionAPI interface used for examining and modifying the light-linking of this light.

GetMaterialSyncModeAttr() For a LightAPI applied to geometry that has a bound Material, which is entirely or partly emissive, this specifies the relationship of the Material response to the lighting response.

GetNormalizeAttr() Normalizes power by the surface area of the light.

GetOutput(name) Return the requested output if it exists.

GetOutputs(onlyAuthored) Outputs are represented by attributes in the"outputs:"namespace.

GetSchemaAttributeNames classmethod GetSchemaAttributeNames(includeInherited) -> list[TfToken]

GetShaderId(renderContexts) Return the light's shader ID for the given list of available renderContexts .

GetShaderIdAttr() Default ID for the light's shader.

GetShaderIdAttrForRenderContext(renderContext) Returns the shader ID attribute for the given renderContext .

GetShadowLinkCollectionAPI() Return the UsdCollectionAPI interface used for examining and modifying the shadow-linking of this light.

GetSpecularAttr() A multiplier for the effect of this light on the specular response of materials.

static Apply() classmethod Apply(prim) -> LightAPI Applies this single-apply API schema to the given prim . This information is stored by adding”LightAPI”to the token-valued, listOp metadata apiSchemas on the prim. A valid UsdLuxLightAPI object is returned upon success. An invalid (or empty) UsdLuxLightAPI object is returned upon failure. See UsdPrim::ApplyAPI() for conditions resulting in failure. UsdPrim::GetAppliedSchemas() UsdPrim::HasAPI() UsdPrim::CanApplyAPI() UsdPrim::ApplyAPI() UsdPrim::RemoveAPI()

Parameters prim (Prim) –

static CanApply() classmethod CanApply(prim, whyNot) -> bool Returns true if this single-apply API schema can be applied to the given prim . If this schema can not be a applied to the prim, this returns false and, if provided, populates whyNot with the reason it can not be applied. Note that if CanApply returns false, that does not necessarily imply that calling Apply will fail. Callers are expected to call CanApply before calling Apply if they want to ensure that it is valid to apply a schema. UsdPrim::GetAppliedSchemas() UsdPrim::HasAPI() UsdPrim::CanApplyAPI() UsdPrim::ApplyAPI() UsdPrim::RemoveAPI()

Parameters

prim (Prim) – whyNot (str) –

ConnectableAPI() → ConnectableAPI Contructs and returns a UsdShadeConnectableAPI object with this light. Note that most tasks can be accomplished without explicitly constructing a UsdShadeConnectable API, since connection-related API such as UsdShadeConnectableAPI::ConnectToSource() are static methods, and UsdLuxLightAPI will auto-convert to a UsdShadeConnectableAPI when passed to functions that want to act generically on a connectable UsdShadeConnectableAPI object.

CreateColorAttr(defaultValue, writeSparsely) → Attribute See GetColorAttr() , and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateColorTemperatureAttr(defaultValue, writeSparsely) → Attribute See GetColorTemperatureAttr() , and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateDiffuseAttr(defaultValue, writeSparsely) → Attribute See GetDiffuseAttr() , and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateEnableColorTemperatureAttr(defaultValue, writeSparsely) → Attribute See GetEnableColorTemperatureAttr() , and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateExposureAttr(defaultValue, writeSparsely) → Attribute See GetExposureAttr() , and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateFiltersRel() → Relationship See GetFiltersRel() , and also Create vs Get Property Methods for when to use Get vs Create.

CreateInput(name, typeName) → Input Create an input which can either have a value or can be connected. The attribute representing the input is created in the”inputs:”namespace. Inputs on lights are connectable.

Parameters

name (str) – typeName (ValueTypeName) –

CreateIntensityAttr(defaultValue, writeSparsely) → Attribute See GetIntensityAttr() , and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateMaterialSyncModeAttr(defaultValue, writeSparsely) → Attribute See GetMaterialSyncModeAttr() , and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateNormalizeAttr(defaultValue, writeSparsely) → Attribute See GetNormalizeAttr() , and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateOutput(name, typeName) → Output Create an output which can either have a value or can be connected. The attribute representing the output is created in the”outputs:”namespace. Outputs on a light cannot be connected, as their value is assumed to be computed externally.

Parameters

name (str) – typeName (ValueTypeName) –

CreateShaderIdAttr(defaultValue, writeSparsely) → Attribute See GetShaderIdAttr() , and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateShaderIdAttrForRenderContext(renderContext, defaultValue, writeSparsely) → Attribute Creates the shader ID attribute for the given renderContext . See GetShaderIdAttrForRenderContext() , and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false .

Parameters

renderContext (str) – defaultValue (VtValue) – writeSparsely (bool) –

CreateSpecularAttr(defaultValue, writeSparsely) → Attribute See GetSpecularAttr() , and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

static Get() classmethod Get(stage, path) -> LightAPI Return a UsdLuxLightAPI holding the prim adhering to this schema at path on stage . If no prim exists at path on stage , or if the prim at that path does not adhere to this schema, return an invalid schema object. This is shorthand for the following: UsdLuxLightAPI(stage->GetPrimAtPath(path));

Parameters

stage (Stage) – path (Path) –

GetColorAttr() → Attribute The color of emitted light, in energy-linear terms. Declaration color3f inputs:color = (1, 1, 1) C++ Type GfVec3f Usd Type SdfValueTypeNames->Color3f

GetColorTemperatureAttr() → Attribute Color temperature, in degrees Kelvin, representing the white point. The default is a common white point, D65. Lower values are warmer and higher values are cooler. The valid range is from 1000 to 10000. Only takes effect when enableColorTemperature is set to true. When active, the computed result multiplies against the color attribute. See UsdLuxBlackbodyTemperatureAsRgb() . Declaration float inputs:colorTemperature = 6500 C++ Type float Usd Type SdfValueTypeNames->Float

GetDiffuseAttr() → Attribute A multiplier for the effect of this light on the diffuse response of materials. This is a non-physical control. Declaration float inputs:diffuse = 1 C++ Type float Usd Type SdfValueTypeNames->Float

GetEnableColorTemperatureAttr() → Attribute Enables using colorTemperature. Declaration bool inputs:enableColorTemperature = 0 C++ Type bool Usd Type SdfValueTypeNames->Bool

GetExposureAttr() → Attribute Scales the power of the light exponentially as a power of 2 (similar to an F-stop control over exposure). The result is multiplied against the intensity. Declaration float inputs:exposure = 0 C++ Type float Usd Type SdfValueTypeNames->Float

GetFiltersRel() → Relationship Relationship to the light filters that apply to this light.

GetInput(name) → Input Return the requested input if it exists.

Parameters name (str) –

GetInputs(onlyAuthored) → list[Input] Inputs are represented by attributes in the”inputs:”namespace. If onlyAuthored is true (the default), then only return authored attributes; otherwise, this also returns un-authored builtins.

Parameters onlyAuthored (bool) –

GetIntensityAttr() → Attribute Scales the power of the light linearly. Declaration float inputs:intensity = 1 C++ Type float Usd Type SdfValueTypeNames->Float

GetLightLinkCollectionAPI() → CollectionAPI Return the UsdCollectionAPI interface used for examining and modifying the light-linking of this light. Light-linking controls which geometry this light illuminates.

GetMaterialSyncModeAttr() → Attribute For a LightAPI applied to geometry that has a bound Material, which is entirely or partly emissive, this specifies the relationship of the Material response to the lighting response. Valid values are:

materialGlowTintsLight: All primary and secondary rays see the emissive/glow response as dictated by the bound Material while the base color seen by light rays (which is then modulated by all of the other LightAPI controls) is the multiplication of the color feeding the emission/glow input of the Material (i.e. its surface or volume shader) with the scalar or pattern input to inputs:color. This allows the light’s color to tint the geometry’s glow color while preserving access to intensity and other light controls as ways to further modulate the illumination. independent: All primary and secondary rays see the emissive/glow response as dictated by the bound Material, while the base color seen by light rays is determined solely by inputs:color. Note that for partially emissive geometry (in which some parts are reflective rather than emissive), a suitable pattern must be connected to the light’s color input, or else the light will radiate uniformly from the geometry. noMaterialResponse: The geometry behaves as if there is no Material bound at all, i.e. there is no diffuse, specular, or transmissive response. The base color of light rays is entirely controlled by the inputs:color. This is the standard mode for”canonical”lights in UsdLux and indicates to renderers that a Material will either never be bound or can always be ignored.

Declaration uniform token light:materialSyncMode ="noMaterialResponse" C++ Type TfToken Usd Type SdfValueTypeNames->Token Variability SdfVariabilityUniform Allowed Values materialGlowTintsLight, independent, noMaterialResponse

GetNormalizeAttr() → Attribute Normalizes power by the surface area of the light. This makes it easier to independently adjust the power and shape of the light, by causing the power to not vary with the area or angular size of the light. Declaration bool inputs:normalize = 0 C++ Type bool Usd Type SdfValueTypeNames->Bool

GetOutput(name) → Output Return the requested output if it exists.

Parameters name (str) –

GetOutputs(onlyAuthored) → list[Output] Outputs are represented by attributes in the”outputs:”namespace. If onlyAuthored is true (the default), then only return authored attributes; otherwise, this also returns un-authored builtins.

Parameters onlyAuthored (bool) –

Parameters includeInherited (bool) –

GetShaderId(renderContexts) → str Return the light’s shader ID for the given list of available renderContexts . The shader ID returned by this function is the identifier to use when looking up the shader definition for this light in the shader registry. The render contexts are expected to be listed in priority order, so for each render context provided, this will try to find the shader ID attribute specific to that render context (see GetShaderIdAttrForRenderContext() ) and will return the value of the first one found that has a non-empty value. If no shader ID value can be found for any of the given render contexts or renderContexts is empty, then this will return the value of the default shader ID attribute (see GetShaderIdAttr() ).

Parameters renderContexts (list[TfToken]) –

GetShaderIdAttr() → Attribute Default ID for the light’s shader. This defines the shader ID for this light when a render context specific shader ID is not available. The default shaderId for the intrinsic UsdLux lights (RectLight, DistantLight, etc.) are set to default to the light’s type name. For each intrinsic UsdLux light, we will always register an SdrShaderNode in the SdrRegistry, with the identifier matching the type name and the source type”USD”, that corresponds to the light’s inputs. GetShaderId GetShaderIdAttrForRenderContext SdrRegistry::GetShaderNodeByIdentifier SdrRegistry::GetShaderNodeByIdentifierAndType Declaration uniform token light:shaderId ="" C++ Type TfToken Usd Type SdfValueTypeNames->Token Variability SdfVariabilityUniform

GetShaderIdAttrForRenderContext(renderContext) → Attribute Returns the shader ID attribute for the given renderContext . If renderContext is non-empty, this will try to return an attribute named light:shaderId with the namespace prefix renderContext . For example, if the passed in render context is”ri”then the attribute returned by this function would have the following signature: Declaration token ri:light:shaderId C++ Type TfToken Usd Type SdfValueTypeNames->Token If the render context is empty, this will return the default shader ID attribute as returned by GetShaderIdAttr() .

Parameters renderContext (str) –

GetShadowLinkCollectionAPI() → CollectionAPI Return the UsdCollectionAPI interface used for examining and modifying the shadow-linking of this light. Shadow-linking controls which geometry casts shadows from this light.

GetSpecularAttr() → Attribute A multiplier for the effect of this light on the specular response of materials. This is a non-physical control. Declaration float inputs:specular = 1 C++ Type float Usd Type SdfValueTypeNames->Float

class pxr.UsdLux.LightFilter A light filter modifies the effect of a light. Lights refer to filters via relationships so that filters may be shared. Linking Filters can be linked to geometry. Linking controls which geometry a light-filter affects, when considering the light filters attached to a light illuminating the geometry. Linking is specified as a collection (UsdCollectionAPI) which can be accessed via GetFilterLinkCollection(). For any described attribute Fallback Value or Allowed Values below that are text/tokens, the actual token is published and defined in UsdLuxTokens. So to set an attribute to the value”rightHanded”, use UsdLuxTokens->rightHanded as the value. Methods:

ConnectableAPI() Contructs and returns a UsdShadeConnectableAPI object with this light filter.

CreateInput(name, typeName) Create an input which can either have a value or can be connected.

CreateOutput(name, typeName) Create an output which can either have a value or can be connected.

CreateShaderIdAttr(defaultValue, writeSparsely) See GetShaderIdAttr() , and also Create vs Get Property Methods for when to use Get vs Create.

CreateShaderIdAttrForRenderContext(...) Creates the shader ID attribute for the given renderContext .

Define classmethod Define(stage, path) -> LightFilter

Get classmethod Get(stage, path) -> LightFilter

GetFilterLinkCollectionAPI() Return the UsdCollectionAPI interface used for examining and modifying the filter-linking of this light filter.

GetInput(name) Return the requested input if it exists.

GetInputs(onlyAuthored) Inputs are represented by attributes in the"inputs:"namespace.

GetOutput(name) Return the requested output if it exists.

GetOutputs(onlyAuthored) Outputs are represented by attributes in the"outputs:"namespace.

GetSchemaAttributeNames classmethod GetSchemaAttributeNames(includeInherited) -> list[TfToken]

GetShaderId(renderContexts) Return the light filter's shader ID for the given list of available renderContexts .

GetShaderIdAttr() Default ID for the light filter's shader.

GetShaderIdAttrForRenderContext(renderContext) Returns the shader ID attribute for the given renderContext .

ConnectableAPI() → ConnectableAPI Contructs and returns a UsdShadeConnectableAPI object with this light filter. Note that most tasks can be accomplished without explicitly constructing a UsdShadeConnectable API, since connection-related API such as UsdShadeConnectableAPI::ConnectToSource() are static methods, and UsdLuxLightFilter will auto-convert to a UsdShadeConnectableAPI when passed to functions that want to act generically on a connectable UsdShadeConnectableAPI object.

Parameters

name (str) – typeName (ValueTypeName) –

CreateOutput(name, typeName) → Output Create an output which can either have a value or can be connected. The attribute representing the output is created in the”outputs:”namespace. Outputs on a light filter cannot be connected, as their value is assumed to be computed externally.

Parameters

name (str) – typeName (ValueTypeName) –

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

Parameters

renderContext (str) – defaultValue (VtValue) – writeSparsely (bool) –

static Define() classmethod Define(stage, path) -> LightFilter Attempt to ensure a UsdPrim adhering to this schema at path is defined (according to UsdPrim::IsDefined() ) on this stage. If a prim adhering to this schema at path is already defined on this stage, return that prim. Otherwise author an SdfPrimSpec with specifier == SdfSpecifierDef and this schema’s prim type name for the prim at path at the current EditTarget. Author SdfPrimSpec s with specifier == SdfSpecifierDef and empty typeName at the current EditTarget for any nonexistent, or existing but not Defined ancestors. The given path must be an absolute prim path that does not contain any variant selections. If it is impossible to author any of the necessary PrimSpecs, (for example, in case path cannot map to the current UsdEditTarget ‘s namespace) issue an error and return an invalid UsdPrim. Note that this method may return a defined prim whose typeName does not specify this schema class, in case a stronger typeName opinion overrides the opinion at the current EditTarget.

Parameters

stage (Stage) – path (Path) –

static Get() classmethod Get(stage, path) -> LightFilter Return a UsdLuxLightFilter holding the prim adhering to this schema at path on stage . If no prim exists at path on stage , or if the prim at that path does not adhere to this schema, return an invalid schema object. This is shorthand for the following: UsdLuxLightFilter(stage->GetPrimAtPath(path));

Parameters

stage (Stage) – path (Path) –

GetFilterLinkCollectionAPI() → CollectionAPI Return the UsdCollectionAPI interface used for examining and modifying the filter-linking of this light filter. Linking controls which geometry this light filter affects.

GetInput(name) → Input Return the requested input if it exists.

Parameters name (str) –

Parameters onlyAuthored (bool) –

GetOutput(name) → Output Return the requested output if it exists.

Parameters name (str) –

Parameters onlyAuthored (bool) –

Parameters includeInherited (bool) –

GetShaderId(renderContexts) → str Return the light filter’s shader ID for the given list of available renderContexts . The shader ID returned by this function is the identifier to use when looking up the shader definition for this light filter in the shader registry. The render contexts are expected to be listed in priority order, so for each render context provided, this will try to find the shader ID attribute specific to that render context (see GetShaderIdAttrForRenderContext() ) and will return the value of the first one found that has a non-empty value. If no shader ID value can be found for any of the given render contexts or renderContexts is empty, then this will return the value of the default shader ID attribute (see GetShaderIdAttr() ).

Parameters renderContexts (list[TfToken]) –

GetShaderIdAttr() → Attribute Default ID for the light filter’s shader. This defines the shader ID for this light filter when a render context specific shader ID is not available. GetShaderId GetShaderIdAttrForRenderContext SdrRegistry::GetShaderNodeByIdentifier SdrRegistry::GetShaderNodeByIdentifierAndType Declaration uniform token lightFilter:shaderId ="" C++ Type TfToken Usd Type SdfValueTypeNames->Token Variability SdfVariabilityUniform

GetShaderIdAttrForRenderContext(renderContext) → Attribute Returns the shader ID attribute for the given renderContext . If renderContext is non-empty, this will try to return an attribute named lightFilter:shaderId with the namespace prefix renderContext . For example, if the passed in render context is”ri”then the attribute returned by this function would have the following signature: Declaration token ri:lightFilter:shaderId C++ Type TfToken Usd Type SdfValueTypeNames->Token If the render context is empty, this will return the default shader ID attribute as returned by GetShaderIdAttr() .

Parameters renderContext (str) –

class pxr.UsdLux.LightListAPI API schema to support discovery and publishing of lights in a scene.

Discovering Lights via Traversal

To motivate this API, consider what is required to discover all lights in a scene. We must load all payloads and traverse all prims: 01 // Load everything on the stage so we can find all lights, 02 // including those inside payloads 03 stage->Load(); 04 05 // Traverse all prims, checking if they have an applied UsdLuxLightAPI 06 // (Note: ignoring instancing and a few other things for simplicity) 07 SdfPathVector lights; 08 for (UsdPrim prim: stage->Traverse()) { 09 if (prim.HasAPI()) { 10 lights.push_back(i->GetPath()); 11 } 12 }

This traversal suitably elaborated to handle certain details is the first and simplest thing UsdLuxLightListAPI provides. UsdLuxLightListAPI::ComputeLightList() performs this traversal and returns all lights in the scene: 01 UsdLuxLightListAPI listAPI(stage->GetPseudoRoot()); 02 SdfPathVector lights = listAPI.ComputeLightList();

Publishing a Cached Light List

Consider a USD client that needs to quickly discover lights but wants to defer loading payloads and traversing the entire scene where possible, and is willing to do up-front computation and caching to achieve that. UsdLuxLightListAPI provides a way to cache the computed light list, by publishing the list of lights onto prims in the model hierarchy. Consider a big set that contains lights: 01 def Xform "BigSetWithLights" ( 02 kind = "assembly" 03 payload = @BigSetWithLights.usd@ // Heavy payload 04 ) { 05 // Pre-computed, cached list of lights inside payload 06 rel lightList = [ 07 <./Lights/light_1>, 08 <./Lights/light_2>, 09 ... 10 ] 11 token lightList:cacheBehavior = "consumeAndContinue"; 12 }

The lightList relationship encodes a set of lights, and the lightList:cacheBehavior property provides fine-grained control over how to use that cache. (See details below.) The cache can be created by first invoking ComputeLightList(ComputeModeIgnoreCache) to pre-compute the list and then storing the result with UsdLuxLightListAPI::StoreLightList() . To enable efficient retrieval of the cache, it should be stored on a model hierarchy prim. Furthermore, note that while you can use a UsdLuxLightListAPI bound to the pseudo-root prim to query the lights (as in the example above) because it will perform a traversal over descendants, you cannot store the cache back to the pseduo-root prim. To consult the cached list, we invoke ComputeLightList(ComputeModeConsultModelHierarchyCache): 01 // Find and load all lights, using lightList cache where available 02 UsdLuxLightListAPI list(stage->GetPseudoRoot()); 03 SdfPathSet lights = list.ComputeLightList( 04 UsdLuxLightListAPI::ComputeModeConsultModelHierarchyCache); 05 stage.LoadAndUnload(lights, SdfPathSet());

In this mode, ComputeLightList() will traverse the model hierarchy, accumulating cached light lists.

Controlling Cache Behavior

The lightList:cacheBehavior property gives additional fine-grained control over cache behavior:

The fallback value,”ignore”, indicates that the lightList should be disregarded. This provides a way to invalidate cache entries. Note that unless”ignore”is specified, a lightList with an empty list of targets is considered a cache indicating that no lights are present. The value”consumeAndContinue”indicates that the cache should be consulted to contribute lights to the scene, and that recursion should continue down the model hierarchy in case additional lights are added as descedants. This is the default value established when StoreLightList() is invoked. This behavior allows the lights within a large model, such as the BigSetWithLights example above, to be published outside the payload, while also allowing referencing and layering to add additional lights over that set. The value”consumeAndHalt”provides a way to terminate recursive traversal of the scene for light discovery. The cache will be consulted but no descendant prims will be examined.

Instancing

Where instances are present, UsdLuxLightListAPI::ComputeLightList() will return the instance-unique paths to any lights discovered within those instances. Lights within a UsdGeomPointInstancer will not be returned, however, since they cannot be referred to solely via paths. For any described attribute Fallback Value or Allowed Values below that are text/tokens, the actual token is published and defined in UsdLuxTokens. So to set an attribute to the value”rightHanded”, use UsdLuxTokens->rightHanded as the value. Classes:

ComputeMode Runtime control over whether to consult stored lightList caches.

Methods:

Apply classmethod Apply(prim) -> LightListAPI

CanApply classmethod CanApply(prim, whyNot) -> bool

ComputeLightList(mode) Computes and returns the list of lights and light filters in the stage, optionally consulting a cached result.

CreateLightListCacheBehaviorAttr(...) See GetLightListCacheBehaviorAttr() , and also Create vs Get Property Methods for when to use Get vs Create.

CreateLightListRel() See GetLightListRel() , and also Create vs Get Property Methods for when to use Get vs Create.

Get classmethod Get(stage, path) -> LightListAPI

GetLightListCacheBehaviorAttr() Controls how the lightList should be interpreted.

GetLightListRel() Relationship to lights in the scene.

GetSchemaAttributeNames classmethod GetSchemaAttributeNames(includeInherited) -> list[TfToken]

InvalidateLightList() Mark any stored lightlist as invalid, by setting the lightList:cacheBehavior attribute to ignore.

StoreLightList(arg1) Store the given paths as the lightlist for this prim.

Attributes:

ComputeModeConsultModelHierarchyCache

ComputeModeIgnoreCache

class ComputeMode Runtime control over whether to consult stored lightList caches. Methods:

GetValueFromName

Attributes:

allValues

static GetValueFromName()

allValues = (UsdLux.LightListAPI.ComputeModeConsultModelHierarchyCache, UsdLux.LightListAPI.ComputeModeIgnoreCache)

static Apply() classmethod Apply(prim) -> LightListAPI Applies this single-apply API schema to the given prim . This information is stored by adding”LightListAPI”to the token-valued, listOp metadata apiSchemas on the prim. A valid UsdLuxLightListAPI object is returned upon success. An invalid (or empty) UsdLuxLightListAPI object is returned upon failure. See UsdPrim::ApplyAPI() for conditions resulting in failure. UsdPrim::GetAppliedSchemas() UsdPrim::HasAPI() UsdPrim::CanApplyAPI() UsdPrim::ApplyAPI() UsdPrim::RemoveAPI()

Parameters prim (Prim) –

Parameters

prim (Prim) – whyNot (str) –

ComputeLightList(mode) → SdfPathSet Computes and returns the list of lights and light filters in the stage, optionally consulting a cached result. In ComputeModeIgnoreCache mode, caching is ignored, and this does a prim traversal looking for prims that have a UsdLuxLightAPI or are of type UsdLuxLightFilter. In ComputeModeConsultModelHierarchyCache, this does a traversal only of the model hierarchy. In this traversal, any lights that live as model hierarchy prims are accumulated, as well as any paths stored in lightList caches. The lightList:cacheBehavior attribute gives further control over the cache behavior; see the class overview for details. When instances are present, ComputeLightList(ComputeModeIgnoreCache) will return the instance-uniqiue paths to any lights discovered within those instances. Lights within a UsdGeomPointInstancer will not be returned, however, since they cannot be referred to solely via paths.

Parameters mode (ComputeMode) –

CreateLightListCacheBehaviorAttr(defaultValue, writeSparsely) → Attribute See GetLightListCacheBehaviorAttr() , and also Create vs Get Property Methods for when to use Get vs Create. If specified, author defaultValue as the attribute’s default, sparsely (when it makes sense to do so) if writeSparsely is true - the default for writeSparsely is false .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateLightListRel() → Relationship See GetLightListRel() , and also Create vs Get Property Methods for when to use Get vs Create.

static Get() classmethod Get(stage, path) -> LightListAPI Return a UsdLuxLightListAPI holding the prim adhering to this schema at path on stage . If no prim exists at path on stage , or if the prim at that path does not adhere to this schema, return an invalid schema object. This is shorthand for the following: UsdLuxLightListAPI(stage->GetPrimAtPath(path));

Parameters

stage (Stage) – path (Path) –

GetLightListCacheBehaviorAttr() → Attribute Controls how the lightList should be interpreted. Valid values are:

consumeAndHalt: The lightList should be consulted, and if it exists, treated as a final authoritative statement of any lights that exist at or below this prim, halting recursive discovery of lights. consumeAndContinue: The lightList should be consulted, but recursive traversal over nameChildren should continue in case additional lights are added by descendants. ignore: The lightList should be entirely ignored. This provides a simple way to temporarily invalidate an existing cache. This is the fallback behavior.

Declaration token lightList:cacheBehavior C++ Type TfToken Usd Type SdfValueTypeNames->Token Allowed Values consumeAndHalt, consumeAndContinue, ignore

GetLightListRel() → Relationship Relationship to lights in the scene.

Parameters includeInherited (bool) –

InvalidateLightList() → None Mark any stored lightlist as invalid, by setting the lightList:cacheBehavior attribute to ignore.

StoreLightList(arg1) → None Store the given paths as the lightlist for this prim. Paths that do not have this prim’s path as a prefix will be silently ignored. This will set the listList:cacheBehavior to”consumeAndContinue”.

Parameters arg1 (SdfPathSet) –

ComputeModeConsultModelHierarchyCache = UsdLux.LightListAPI.ComputeModeConsultModelHierarchyCache

ComputeModeIgnoreCache = UsdLux.LightListAPI.ComputeModeIgnoreCache

class pxr.UsdLux.ListAPI Deprecated Use LightListAPI instead For any described attribute Fallback Value or Allowed Values below that are text/tokens, the actual token is published and defined in UsdLuxTokens. So to set an attribute to the value”rightHanded”, use UsdLuxTokens->rightHanded as the value. Classes:

ComputeMode Runtime control over whether to consult stored lightList caches.

Methods:

Apply classmethod Apply(prim) -> ListAPI

CanApply classmethod CanApply(prim, whyNot) -> bool

ComputeLightList(mode) Computes and returns the list of lights and light filters in the stage, optionally consulting a cached result.

CreateLightListCacheBehaviorAttr(...) See GetLightListCacheBehaviorAttr() , and also Create vs Get Property Methods for when to use Get vs Create.

CreateLightListRel() See GetLightListRel() , and also Create vs Get Property Methods for when to use Get vs Create.

Get classmethod Get(stage, path) -> ListAPI

GetLightListCacheBehaviorAttr() Controls how the lightList should be interpreted.

GetLightListRel() Relationship to lights in the scene.

GetSchemaAttributeNames classmethod GetSchemaAttributeNames(includeInherited) -> list[TfToken]

InvalidateLightList() Mark any stored lightlist as invalid, by setting the lightList:cacheBehavior attribute to ignore.

StoreLightList(arg1) Store the given paths as the lightlist for this prim.

Attributes:

ComputeModeConsultModelHierarchyCache

ComputeModeIgnoreCache

class ComputeMode Runtime control over whether to consult stored lightList caches. Methods:

GetValueFromName

Attributes:

allValues

static GetValueFromName()

allValues = (UsdLux.ListAPI.ComputeModeConsultModelHierarchyCache, UsdLux.ListAPI.ComputeModeIgnoreCache)

static Apply() classmethod Apply(prim) -> ListAPI Applies this single-apply API schema to the given prim . This information is stored by adding”ListAPI”to the token-valued, listOp metadata apiSchemas on the prim. A valid UsdLuxListAPI object is returned upon success. An invalid (or empty) UsdLuxListAPI object is returned upon failure. See UsdPrim::ApplyAPI() for conditions resulting in failure. UsdPrim::GetAppliedSchemas() UsdPrim::HasAPI() UsdPrim::CanApplyAPI() UsdPrim::ApplyAPI() UsdPrim::RemoveAPI()

Parameters prim (Prim) –

Parameters

prim (Prim) – whyNot (str) –

Parameters mode (ComputeMode) –

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateLightListRel() → Relationship See GetLightListRel() , and also Create vs Get Property Methods for when to use Get vs Create.

static Get() classmethod Get(stage, path) -> ListAPI Return a UsdLuxListAPI holding the prim adhering to this schema at path on stage . If no prim exists at path on stage , or if the prim at that path does not adhere to this schema, return an invalid schema object. This is shorthand for the following: UsdLuxListAPI(stage->GetPrimAtPath(path));

Parameters

stage (Stage) – path (Path) –

GetLightListCacheBehaviorAttr() → Attribute Controls how the lightList should be interpreted. Valid values are:

Declaration token lightList:cacheBehavior C++ Type TfToken Usd Type SdfValueTypeNames->Token Allowed Values consumeAndHalt, consumeAndContinue, ignore

GetLightListRel() → Relationship Relationship to lights in the scene.

Parameters includeInherited (bool) –

InvalidateLightList() → None Mark any stored lightlist as invalid, by setting the lightList:cacheBehavior attribute to ignore.

Parameters arg1 (SdfPathSet) –

ComputeModeConsultModelHierarchyCache = UsdLux.ListAPI.ComputeModeConsultModelHierarchyCache

ComputeModeIgnoreCache = UsdLux.ListAPI.ComputeModeIgnoreCache

class pxr.UsdLux.MeshLightAPI This is the preferred API schema to apply to Mesh type prims when adding light behaviors to a mesh. At its base, this API schema has the built-in behavior of applying LightAPI to the mesh and overriding the default materialSyncMode to allow the emission/glow of the bound material to affect the color of the light. But, it additionally serves as a hook for plugins to attach additional properties to”mesh lights”through the creation of API schemas which are authored to auto- apply to MeshLightAPI. Auto applied API schemas Methods:

Apply classmethod Apply(prim) -> MeshLightAPI

CanApply classmethod CanApply(prim, whyNot) -> bool

Get classmethod Get(stage, path) -> MeshLightAPI

GetSchemaAttributeNames classmethod GetSchemaAttributeNames(includeInherited) -> list[TfToken]

static Apply() classmethod Apply(prim) -> MeshLightAPI Applies this single-apply API schema to the given prim . This information is stored by adding”MeshLightAPI”to the token-valued, listOp metadata apiSchemas on the prim. A valid UsdLuxMeshLightAPI object is returned upon success. An invalid (or empty) UsdLuxMeshLightAPI object is returned upon failure. See UsdPrim::ApplyAPI() for conditions resulting in failure. UsdPrim::GetAppliedSchemas() UsdPrim::HasAPI() UsdPrim::CanApplyAPI() UsdPrim::ApplyAPI() UsdPrim::RemoveAPI()

Parameters prim (Prim) –

Parameters

prim (Prim) – whyNot (str) –

static Get() classmethod Get(stage, path) -> MeshLightAPI Return a UsdLuxMeshLightAPI holding the prim adhering to this schema at path on stage . If no prim exists at path on stage , or if the prim at that path does not adhere to this schema, return an invalid schema object. This is shorthand for the following: UsdLuxMeshLightAPI(stage->GetPrimAtPath(path));

Parameters

stage (Stage) – path (Path) –

Parameters includeInherited (bool) –

class pxr.UsdLux.NonboundableLightBase Base class for intrinsic lights that are not boundable. The primary purpose of this class is to provide a direct API to the functions provided by LightAPI for concrete derived light types. Methods:

CreateColorAttr(defaultValue, writeSparsely) See UsdLuxLightAPI::CreateColorAttr() .

CreateColorTemperatureAttr(defaultValue, ...) See UsdLuxLightAPI::CreateColorTemperatureAttr() .

CreateDiffuseAttr(defaultValue, writeSparsely) See UsdLuxLightAPI::CreateDiffuseAttr() .

CreateEnableColorTemperatureAttr(...) See UsdLuxLightAPI::CreateEnableColorTemperatureAttr() .

CreateExposureAttr(defaultValue, writeSparsely) See UsdLuxLightAPI::CreateExposureAttr() .

CreateFiltersRel() See UsdLuxLightAPI::CreateFiltersRel() .

CreateIntensityAttr(defaultValue, writeSparsely) See UsdLuxLightAPI::CreateIntensityAttr() .

CreateNormalizeAttr(defaultValue, writeSparsely) See UsdLuxLightAPI::CreateNormalizeAttr() .

CreateSpecularAttr(defaultValue, writeSparsely) See UsdLuxLightAPI::CreateSpecularAttr() .

Get classmethod Get(stage, path) -> NonboundableLightBase

GetColorAttr() See UsdLuxLightAPI::GetColorAttr() .

GetColorTemperatureAttr() See UsdLuxLightAPI::GetColorTemperatureAttr() .

GetDiffuseAttr() See UsdLuxLightAPI::GetDiffuseAttr() .

GetEnableColorTemperatureAttr() See UsdLuxLightAPI::GetEnableColorTemperatureAttr() .

GetExposureAttr() See UsdLuxLightAPI::GetExposureAttr() .

GetFiltersRel() See UsdLuxLightAPI::GetFiltersRel() .

GetIntensityAttr() See UsdLuxLightAPI::GetIntensityAttr() .

GetNormalizeAttr() See UsdLuxLightAPI::GetNormalizeAttr() .

GetSchemaAttributeNames classmethod GetSchemaAttributeNames(includeInherited) -> list[TfToken]

GetSpecularAttr() See UsdLuxLightAPI::GetSpecularAttr() .

LightAPI() Contructs and returns a UsdLuxLightAPI object for this light.

CreateColorAttr(defaultValue, writeSparsely) → Attribute See UsdLuxLightAPI::CreateColorAttr() .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateColorTemperatureAttr(defaultValue, writeSparsely) → Attribute See UsdLuxLightAPI::CreateColorTemperatureAttr() .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateDiffuseAttr(defaultValue, writeSparsely) → Attribute See UsdLuxLightAPI::CreateDiffuseAttr() .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateEnableColorTemperatureAttr(defaultValue, writeSparsely) → Attribute See UsdLuxLightAPI::CreateEnableColorTemperatureAttr() .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateExposureAttr(defaultValue, writeSparsely) → Attribute See UsdLuxLightAPI::CreateExposureAttr() .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateFiltersRel() → Relationship See UsdLuxLightAPI::CreateFiltersRel() .

CreateIntensityAttr(defaultValue, writeSparsely) → Attribute See UsdLuxLightAPI::CreateIntensityAttr() .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateNormalizeAttr(defaultValue, writeSparsely) → Attribute See UsdLuxLightAPI::CreateNormalizeAttr() .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

CreateSpecularAttr(defaultValue, writeSparsely) → Attribute See UsdLuxLightAPI::CreateSpecularAttr() .

Parameters

defaultValue (VtValue) – writeSparsely (bool) –

static Get() classmethod Get(stage, path) -> NonboundableLightBase Return a UsdLuxNonboundableLightBase holding the prim adhering to this schema at path on stage . If no prim exists at path on stage , or if the prim at that path does not adhere to this schema, return an invalid schema object. This is shorthand for the following: UsdLuxNonboundableLightBase(stage->GetPrimAtPath(path));