uniforms
An object whose properties are used to set the uniforms of the fragment shader.
The object property values can be either a constant or a function. The function will be called each frame before the post-process stage is executed.
A constant value can also be a URI to an image, a data URI, or an HTML element that can be used as a texture, such as HTMLImageElement or HTMLCanvasElement.
If this post-process stage is part of a PostProcessStageComposite that does not execute in series, the constant value can also be the name of another stage in a composite. This will set the uniform to the output texture the stage with that name.