GL_ARB_gpu_shader5 http://www.opengl.org/registry/specs/ARB/gpu_shader5.txt GL_ARB_gpu_shader5 GL_GEOMETRY_SHADER_INVOCATIONS 0x887F GL_MAX_GEOMETRY_SHADER_INVOCATIONS 0x8E5A GL_MIN_FRAGMENT_INTERPOLATION_OFFSET 0x8E5B GL_MAX_FRAGMENT_INTERPOLATION_OFFSET 0x8E5C GL_FRAGMENT_INTERPOLATION_OFFSET_BITS 0x8E5D GL_MAX_VERTEX_STREAMS 0x8E71