GL_ARB_texture_rg http://www.opengl.org/registry/specs/ARB/texture_rg.txt GL_ARB_texture_rg GL_COMPRESSED_RED 0x8225 GL_COMPRESSED_RG 0x8226 GL_RG 0x8227 GL_RG_INTEGER 0x8228 GL_R8 0x8229 GL_R16 0x822A GL_RG8 0x822B GL_RG16 0x822C GL_R16F 0x822D GL_R32F 0x822E GL_RG16F 0x822F GL_RG32F 0x8230 GL_R8I 0x8231 GL_R8UI 0x8232 GL_R16I 0x8233 GL_R16UI 0x8234 GL_R32I 0x8235 GL_R32UI 0x8236 GL_RG8I 0x8237 GL_RG8UI 0x8238 GL_RG16I 0x8239 GL_RG16UI 0x823A GL_RG32I 0x823B GL_RG32UI 0x823C