On 07/17/2014 09:21 AM, Pavel Popov wrote:
According to spec (OpenGL 4.0 specification, pages 254-255) we have a different bits set for one buffer and for multiple buffers. For glDrawBuffer we may have up to four bits set but for glDrawBuffers we can only have one bit set.The _mesa_drawbuffers is called with ctx->Const.MaxDrawBuffers and NULL arguments when _mesa_update_framebuffer or _mesa_update_draw_buffers is called. In this situation realization for glDrawBuffers is used for any number of buffers. Even for one. But glDrawBuffer have to be used for one buffer instead of glDrawBuffers. Piglit test 'gl30basic' fails with assert with debug Mesa and pass with release 'main/buffers.c:520: _mesa_drawbuffers: Assertion `__builtin_popcount(destMask[buf]) == 1' failed.' Probably some other tests also can be affected. Signed-off-by: Pavel Popov <pavel.e.po...@intel.com> --- src/mesa/main/buffers.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/src/mesa/main/buffers.c b/src/mesa/main/buffers.c index b13a7af..a640360 100644 --- a/src/mesa/main/buffers.c +++ b/src/mesa/main/buffers.c @@ -480,6 +480,7 @@ _mesa_drawbuffers(struct gl_context *ctx, GLuint n, const GLenum *buffers, struct gl_framebuffer *fb = ctx->DrawBuffer; GLbitfield mask[MAX_DRAW_BUFFERS]; GLuint buf; + GLuint m = n; if (!destMask) { /* compute destMask values now */ @@ -489,15 +490,17 @@ _mesa_drawbuffers(struct gl_context *ctx, GLuint n, const GLenum *buffers, mask[output] = draw_buffer_enum_to_bitmask(ctx, buffers[output]); ASSERT(mask[output] != BAD_MASK); mask[output] &= supportedMask; + if (mask[output] == 0) + m--; } destMask = mask; } /* - * If n==1, destMask[0] may have up to four bits set. + * If m==1, destMask[0] may have up to four bits set. * Otherwise, destMask[x] can only have one bit set. */ - if (n == 1) { + if (m == 1) { GLuint count = 0, destMask0 = destMask[0]; while (destMask0) { GLint bufIndex = ffs(destMask0) - 1;
Weird. I remembered seeing this assertion a few days ago, but now I can't reproduce it. I don't know what might have changed.
In any case, I don't think the patch is quite right. If the array of buffers was something like {GL_NONE, GL_COLOR_ATTACHMENT1, GL_NONE, GL_NONE} and n=4 you'd wind up with m=1, but you'd be executing the wrong part of the if block.
Instead, I think you'd need to test if (m == 1 && destMask[0]) since it's the 0th entry that requires special validation.
And as someone else pointed out, please word-wrap the commit msg to 70-75 chars.
-Brian _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
