OpenGL ES Shader语言中的函数不支持递归

An example function definition is given here for a simple function that computes basic diffuse lighting:

vec4 diffuse(vec3 normal, vec3 light, vec4 baseColor)

{

    return baseColor * dot(normal, light);

}

One note about functions in the OpenGL ES Shading Language: functions cannot be recursive. The reason for this limitation is that some implementations will implement function calls by actually placing the function code inline in the final generated program for the GPU. The shading language was purposely structured to allow this sort of inline implementation to support GPUs that do not have a stack.