[Mesa-dev] [PATCH v2] mesa: Fix glDrawBuffer/glDrawBuffers logic in _mesa_drawbuffer.
Brian Paul
brianp at vmware.com
Fri Aug 8 14:13:20 PDT 2014
I've come up with a simpler solution. Patch coming soon.
-Brian
On 07/25/2014 04:00 AM, Popov, Pavel E wrote:
> Hi Brian,
>
> Could you commit the updated patch if it's ok?
>
> Regards,
> Pavel
>
> -----Original Message-----
> From: Popov, Pavel E
> Sent: Wednesday, July 23, 2014 4:58 PM
> To: mesa-dev at lists.freedesktop.org
> Cc: Popov, Pavel E
> Subject: [PATCH v2] mesa: Fix glDrawBuffer/glDrawBuffers logic in _mesa_drawbuffer.
>
> Piglit test 'gl30basic' fails on Debug Mesa with the assert:
> 'main/buffers.c:520: _mesa_drawbuffers:
> Assertion `__builtin_popcount(destMask[buf]) == 1' failed.'.
>
> 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 case glDrawBuffers is always used if MaxDrawBuffers > 1.
> But glDrawBuffer has to be used instead of glDrawBuffers if only
> destMask[0] is set.
>
> v2 (Brian Paul): Only 0th entry requires special validation for (m == 1).
>
> Signed-off-by: Pavel Popov <pavel.e.popov at 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..95a8722 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 && destMask[0]) {
> GLuint count = 0, destMask0 = destMask[0];
> while (destMask0) {
> GLint bufIndex = ffs(destMask0) - 1;
> --
> 1.9.1
>
>
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