Development Notes

Adding Extensions

To add a new GL extension to Mesa you have to do at least the following.

  • If glext.h doesn’t define the extension, edit include/GL/gl.h and add code like this:

    #ifndef GL_EXT_the_extension_name
#define GL_EXT_the_extension_name 1
/* declare the new enum tokens */
/* prototype the new functions */
/* TYPEDEFS for the new functions */
#endif

  • In the src/mapi/glapi/gen/ directory, add the new extension functions and enums to the gl_API.xml file. Then, a bunch of source files must be regenerated by executing the corresponding Python scripts.

  • Add a new entry to the gl_extensions struct in consts_exts.h if the extension requires driver capabilities not already exposed by another extension.

  • Add a new entry to the src/mesa/main/extensions_table.h file.

  • From this point, the best way to proceed is to find another extension, similar to the new one, that’s already implemented in Mesa and use it as an example.

  • If the new extension adds new GL state, the functions in get.c, enable.c and attrib.c will most likely require new code.

  • To determine if the new extension is active in the current context, use the auto-generated _mesa_has_##name_str() function defined in src/mesa/main/extensions.h.

  • The dispatch tests check_table.cpp and dispatch_sanity.cpp should be updated with details about the new extensions functions. These tests are run using meson test.