|
.. _scene_guide: |
|
|
|
Creating Scenes |
|
=============== |
|
|
|
Before you render anything, you need to put all of your lights, cameras, |
|
and meshes into a scene. The :class:`.Scene` object keeps track of the relative |
|
poses of these primitives by inserting them into :class:`.Node` objects and |
|
keeping them in a directed acyclic graph. |
|
|
|
Adding Objects |
|
-------------- |
|
|
|
To create a :class:`.Scene`, simply call the constructor. You can optionally |
|
specify an ambient light color and a background color: |
|
|
|
>>> scene = pyrender.Scene(ambient_light=[0.02, 0.02, 0.02], |
|
... bg_color=[1.0, 1.0, 1.0]) |
|
|
|
You can add objects to a scene by first creating a :class:`.Node` object |
|
and adding the object and its pose to the :class:`.Node`. Poses are specified |
|
as 4x4 homogenous transformation matrices that are stored in the node's |
|
:attr:`.Node.matrix` attribute. Note that the :class:`.Node` |
|
constructor requires you to specify whether you're adding a mesh, light, |
|
or camera. |
|
|
|
>>> mesh = pyrender.Mesh.from_trimesh(tm) |
|
>>> light = pyrender.PointLight(color=[1.0, 1.0, 1.0], intensity=2.0) |
|
>>> cam = pyrender.PerspectiveCamera(yfov=np.pi / 3.0, aspectRatio=1.414) |
|
>>> nm = pyrender.Node(mesh=mesh, matrix=np.eye(4)) |
|
>>> nl = pyrender.Node(light=light, matrix=np.eye(4)) |
|
>>> nc = pyrender.Node(camera=cam, matrix=np.eye(4)) |
|
>>> scene.add_node(nm) |
|
>>> scene.add_node(nl) |
|
>>> scene.add_node(nc) |
|
|
|
You can also add objects directly to a scene with the :meth:`.Scene.add` function, |
|
which takes care of creating a :class:`.Node` for you. |
|
|
|
>>> scene.add(mesh, pose=np.eye(4)) |
|
>>> scene.add(light, pose=np.eye(4)) |
|
>>> scene.add(cam, pose=np.eye(4)) |
|
|
|
Nodes can be hierarchical, in which case the node's :attr:`.Node.matrix` |
|
specifies that node's pose relative to its parent frame. You can add nodes to |
|
a scene hierarchically by specifying a parent node in your calls to |
|
:meth:`.Scene.add` or :meth:`.Scene.add_node`: |
|
|
|
>>> scene.add_node(nl, parent_node=nc) |
|
>>> scene.add(cam, parent_node=nm) |
|
|
|
If you add multiple cameras to a scene, you can specify which one to render from |
|
by setting the :attr:`.Scene.main_camera_node` attribute. |
|
|
|
Updating Objects |
|
---------------- |
|
|
|
You can update the poses of existing nodes with the :meth:`.Scene.set_pose` |
|
function. Simply call it with a :class:`.Node` that is already in the scene |
|
and the new pose of that node with respect to its parent as a 4x4 homogenous |
|
transformation matrix: |
|
|
|
>>> scene.set_pose(nl, pose=np.eye(4)) |
|
|
|
If you want to get the local pose of a node, you can just access its |
|
:attr:`.Node.matrix` attribute. However, if you want to the get |
|
the pose of a node *with respect to the world frame*, you can call the |
|
:meth:`.Scene.get_pose` method. |
|
|
|
>>> tf = scene.get_pose(nl) |
|
|
|
Removing Objects |
|
---------------- |
|
|
|
Finally, you can remove a :class:`.Node` and all of its children from the |
|
scene with the :meth:`.Scene.remove_node` function: |
|
|
|
>>> scene.remove_node(nl) |
|
|
