I want to render an environment map into a cubemap framebuffer but I dislike the fact, that I have to use the geometry shader to set
gl_Layer because the geometry shader would be a basic passthrough shader. Additionally a geometry shader could stall the pipeline and decrease performance.
I would rather like to use instanced rendering and set
gl_Layer in the vertex shader but
unfortunately this is only possible with the AMD_vertex_shader_layer extension.
Is there any other way to set the layer in the shader?