Shader Images

Sometimes it can be useful to generate a texture on the fly using a single, static shader. Trial has specific support to make that easy with the image-renderer and cubemap-renderer classes. Those classes act as standard standalone-shader-entitys, but with a special render method that can be called with a texture instance as the render target. The shader output will then be directly rendered onto that texture.

Both renderer classes provide two inputs to the fragment shader stage:

• world_position, the position of the fragment in world space

• uv, the UV coordinate of the texture being rendered to

Additionally, the dynamic-image-renderer class lets you perform the same but with dynamically provided shader code, via dynamic-shader-entity. This is then used to implement the shader-image-generator and the shader-image asset.

The extra arguments to the shader-image asset are the texture parameters. Thus, to define an asset that implements a shader image, you would do something like this:

(define-asset (trial brdf-lut) shader-image
    #p"brdf-lut-renderer.glsl"
  :width 512
  :height 512
  :internal-format :rg16
  :min-filter :linear)

The input file path is, as usual, relative to the pool.