OpenGL 4.3's Framebuffer-No-Attachments Added To Mesa

In addition to this morning's tessellation patches for Mesa, there's more good news today for users of this open-source OpenGL stack that's aspiring for full OpenGL 4 support.

Intel developer Kevin Rogovin has seen his patches land today for implementing the GL_ARB_framebuffer_no_attachments in mainline Mesa. As described by the OpenGL.org registry, ARB_framebuffer_no_attachments provides, the extension enables algorithms to work with a frame-buffer with no attachments. "Applications can specify default width, height, layer count, and sample count parameters for a framebuffer object. When a framebuffer with no attachments is bound, it will be considered complete as long as the application has specified non-zero default width and height parameters. For the purposes of rasterization, the framebuffer will be considered to have a width, height, layer count, and sample count derived from its default parameters. Framebuffers with one or more attachments are not affected by these default parameters; the size of the framebuffer will still be derived from the sizes of the attachments in that case. Additionally, this extension provides queryable implementation-dependent maximums for framebuffer width, height, layer count, and sample count, which may differ from similar limits on textures and renderbuffers."

The patches merged today add the actual driver support just for the i965 DRI driver and it's turned on for Gen7+ hardware. Completing this GL 4.3 requirement just leaves ARB_arrays_of_arrays, ARB_compute_shader, ARB_internalformat_query2, robust_buffer_access_behavior, shader_image_size, and shader_storage_buffer object as the work items left for OpenGL 4.3 compliance (along with the remaining GL 4.0/4.1/4.2 items).