usesRadianceCubeVariant method
Whether shaderForEnvironment picks the cube variant, which is also what decides the radiance texture bound to it. False without a cube variant, so a sky built with only the 2D entry is never handed a cubemap.
Implementation
bool usesRadianceCubeVariant(EnvironmentMap environment) =>
(sampledEnvironment ?? environment).usesCubeRadianceLayout &&
radianceCubeFragmentShader != null;