ref_gl: added support for GL_ARB_texture_compression_bptc extension

ref_gl/gl_export.h

@@ -401,6 +401,10 @@ typedef float GLmatrix[16];
 #define GL_COMPRESSED_RGBA_S3TC_DXT1_EXT	0x83F1
 #define GL_COMPRESSED_RGBA_S3TC_DXT3_EXT	0x83F2
 #define GL_COMPRESSED_RGBA_S3TC_DXT5_EXT	0x83F3
+#define GL_COMPRESSED_RGBA_BPTC_UNORM_ARB           0x8E8C
+#define GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM_ARB     0x8E8D
+#define GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT_ARB     0x8E8E
+#define GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT_ARB   0x8E8F
 #define GL_COMPRESSED_RED_GREEN_RGTC2_EXT	0x8DBD
 #define GL_COMPRESSED_LUMINANCE_ALPHA_3DC_ATI	0x8837
 #define GL_COMPRESSED_ALPHA_ARB		0x84E9

ref_gl/gl_local.h

@@ -623,6 +623,7 @@ enum
 	GL_ARB_VERTEX_BUFFER_OBJECT_EXT,
 	GL_DRAW_RANGEELEMENTS_EXT,
 	GL_TEXTURE_MULTISAMPLE,
+	GL_ARB_TEXTURE_COMPRESSION_BPTC,
 	GL_EXTCOUNT,		// must be last
 };
 

ref_gl/gl_opengl.c

@@ -712,6 +712,7 @@ void GL_InitExtensionsBigGL( void )
 	GL_CheckExtension( "GL_EXT_gpu_shader4", NULL, NULL, GL_EXT_GPU_SHADER4 ); // don't confuse users
 	GL_CheckExtension( "GL_ARB_vertex_buffer_object", vbofuncs, "gl_vertex_buffer_object", GL_ARB_VERTEX_BUFFER_OBJECT_EXT );
 	GL_CheckExtension( "GL_ARB_texture_multisample", multisampletexfuncs, "gl_texture_multisample", GL_TEXTURE_MULTISAMPLE );
+	GL_CheckExtension( "GL_ARB_texture_compression_bptc", NULL, "gl_texture_bptc_compression", GL_ARB_TEXTURE_COMPRESSION_BPTC );
 	if( GL_CheckExtension( "GL_ARB_shading_language_100", NULL, NULL, GL_SHADER_GLSL100_EXT ))
 	{
 		pglGetIntegerv( GL_MAX_TEXTURE_COORDS_ARB, &glConfig.max_texture_coords );