Textured Light#
Textured light is an rectangular polygon light itself except that it’s not monochromatic.
The radiance at each point is determined by texel in an texture. This extends polygon light a lot, since most area light source in real life is colorful, like billboard, screen.
In order to mimic roughness appearance, we will prefilter the texture with different gaussian blur kernel size and store them in texture mipmaps. The prefilter process can be executed once at start up for static textures, or per-frame for realtime changed render textures.
All prefiltered results are stored in an texture atlas, the altas texture is 2048 x 2048, splitted in 4 x 4 cells for each texture.
Currently the cell size is fixed for all textures, that means not matter what the original texture resolution and aspect ration is, it will be fitted into an 512 x 512 cell. Texture with resoltion higher than 512 x 512 will make no difference for textured light.
If original texture’s aspect ratio is far from 1:1, the resulted texture light may lose resolution in one dimension.
A more flexible atlas allocation algorithm should be implemented for textures with different resolution and aspect ratio in the future.
Attributes#
IsRealTime
If true, the texture prefiltering process will be executed each frame, which brings additional cost. Use it for content which is always changing, such as video textures.
Static textures should set IsRealTime to false, otherwise it will be prefiltered each frame even its content is the same, waste GPU resources.
Texture
The texture of this light, it can be a static Texture2D, or runtime generated RenderTexture.
If texture is none, textured light will use default white texture, behaves like rectangular polygon light. You can still adjust color of it.
Width
The width of textured light.
Height
The height of textured light.
Barn Door
There is a special attribute for textured light named barn door, it controls the barn door around textured light and affect how much area it can lit.
Barn Door Length is how long the barn door is. The longer it is, more light will be occluded.
Barn Door Angle is angle of barn door. it ranges from 0 to 90.