2d sprite ambient lighting ambient occlusion anti-aliasing augmented reality bitmap cel shading chromatic abberation direct lighting flat shading fxaa global illumination indirect illumination lumen global illumination manhattan distance microdisplacement nanite geometry path traced pbr material phong shading physically based rendering (pbr) post processed procedural generation procedural texture raster graphics ray traced screen space ambient occlusion skybox terrain rendering tesselation virtual reality volumetric lighting voronoi manhattan voronoi minkowski voxel engine voxel geometry wireframe model wireframe rendering