[Nouveau] [patch] [renouveau] 1/1 fix detection of GL_ARB_draw_buffers in test_framebuffer_object

[Mark Carey]

Further to comments in
http://people.freedesktop.org/~marcheu/irclogs/nouveau-2007-10-20
between 11:30 and 13:51, chowmeined confirmation in
http://people.freedesktop.org/~marcheu/irclogs/nouveau-2007-10-21 at
10:16 of the same behaviour on a second 0322.

It appears that 10de0322 supports GL_EXT_framebuffer_object but does
not support ARB_draw_buffers, accordingly the current fragment program
in renouveau test.c::test_ext_framebuffer_object() causes OpenGL error
1282, 502, INVALID_OPERATION at call to ProgramStringARB on line 4595,
http://oss.sgi.com/projects/ogl-sample/registry/ARB/fragment_program.txt
section 3.11.1 suggests this is due to the illegal token in the
fragment program (fp).

The example code in
http://oss.sgi.com/projects/ogl-sample/registry/ARB/fragment_program.txt
between lines 417 and 429 suggest a method for determining which
character in the fragment program caused the error;

	GLint errorPos;
	regl.GetIntegerv(GL_PROGRAM_ERROR_POSITION_ARB, &errorPos);

Error appears to be firstly `OPTION ARB_draw_buffers;` and secondly
the use of `MOV result.color[%d], fragment.color;` when without
GL_ARB_draw_buffers a syntactically correct line woudl read `MOV
result.color, fragment.color;`.

Furthermore due to incorrect detection of nr_bufs line 4614 or 4615
causes a similar error when the draw buffers test attempts to use a
draw buffer which does not exist on the hardware.

Perusing http://oss.sgi.com/projects/ogl-sample/registry/ARB/draw_buffers.txt
when querying the number of supported draw buffers one should call
GetIntegerv specifying MAX_DRAW_BUFFERS_ARB (0x8824) not
GL_MAX_COLOR_ATTACHMENTS_EXT as currently performed on line 4566.

Attached patch;

1. Defines the constant MAX_DRAW_BUFFERS_ARB (in test.c, which header
should this go into? does it really matter for renouveau?)
2. Correctly uses MAX_DRAW_BUFFERS_ARB to determine the number of draw
buffers present
(http://oss.sgi.com/projects/ogl-sample/registry/ARB/draw_buffers.txt
suggests that OpenGL 1.5 MAX_DRAW_BUFFERS_ARB will always return a
minimum value of 1, will renouveau ever be run on OpenGL<1.5?)
3. Adds a line to `card_10de-xxxx_test_ext_framebuffer_object.txt`
when GL_ARB_draw_buffers is not supported
4. Modifies the fp in the case when MAX_DRAW_BUFFERS_ARB == 1 and
GL_ARB_draw_buffers is not supported
5. Draw buffer test now runs without error (due to 2)

Patch applied to a fresh checkout of renouveau on both 0322
(GL_EXT_framebuffer_object) and 0393 (GL_EXT_framebuffer_object +
GL_ARB_draw_buffers) compiled and tested without error.

Please review and consider applying the attached patch.

Regards,

Mark Carey
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