| GL_EXT_texture_compression_rgtc | |
| http://developer.download.nvidia.com/opengl/specs/GL_EXT_texture_compression_rgtc.txt | |
| GL_COMPRESSED_RED_RGTC1_EXT 0x8DBB | |
| GL_COMPRESSED_SIGNED_RED_RGTC1_EXT 0x8DBC | |
| GL_COMPRESSED_RED_GREEN_RGTC2_EXT 0x8DBD | |
| GL_COMPRESSED_SIGNED_RED_GREEN_RGTC2_EXT 0x8DBE |