radianceCubeFragmentShader property
The variant of fragmentShader built with FLUTTER_SCENE_RADIANCE_CUBE,
used when the active environment's radiance is a cubemap.
Required only for a useEnvironment sky, whose prefiltered_radiance
sampler is a sampler2D or a samplerCube depending on the layout the
backend builds. Without it such a sky samples nothing on a cube backend.
Implementation
gpu.Shader? radianceCubeFragmentShader;