Am 11.08.2014 00:51, schrieb Brian Paul:
> On 08/08/2014 07:43 PM, Roland Scheidegger wrote:
>> Am 08.08.2014 23:20, schrieb Brian Paul:
>>> Fixes failed assertion when _mesa_update_draw_buffers() was called
>>> with GL_DRAW_BUFFER == GL_FRONT_AND_BACK. The piglit gl30basic hit
>>> this.
>>>
>>> Cc: "10.2" <mesa-sta...@lists.freedesktop.org>
>>> ---
>>> src/mesa/main/buffers.c | 5 +++--
>>> 1 file changed, 3 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/src/mesa/main/buffers.c b/src/mesa/main/buffers.c
>>> index b13a7af..6b4fac9 100644
>>> --- a/src/mesa/main/buffers.c
>>> +++ b/src/mesa/main/buffers.c
>>> @@ -494,10 +494,11 @@ _mesa_drawbuffers(struct gl_context *ctx,
>>> GLuint n, const GLenum *buffers,
>>> }
>>>
>>> /*
>>> - * If n==1, destMask[0] may have up to four bits set.
>>> + * destMask[0] may have up to four bits set
>>> + * (ex: glDrawBuffer(GL_FRONT_AND_BACK)).
>>> * Otherwise, destMask[x] can only have one bit set.
>>> */
>>> - if (n == 1) {
>>> + if (_mesa_bitcount(destMask[0]) > 1) {
>>> GLuint count = 0, destMask0 = destMask[0];
>>> while (destMask0) {
>>> GLint bufIndex = ffs(destMask0) - 1;
>>>
>>
>> Hmm I don't understand how that could fail. Either you have a winsys
>> fbo, in which case n has to be 1, or you have a user fbo, in which case
>> you can only have the single color_buffer_x bits.
>> What am I missing here?
>
> It happened when called from _mesa_update_draw_buffers() where n =
> MaxDrawBuffers (8) and the user had previously called
> glDrawBuffer(GL_FRONT_AND_BACK). This could only happen during a
> MakeCurrent() operation.
>
> -Brian
>
Ahh I see now. MakeCurrent() will, unlike the other callers, cause all
(max) draw buffers to be updated, without a destMask, thus n = 8 but
only the first buffer really containing anything useful (the rest
shouldn't be set and their calculated masks all zero). Looks good then.
I wasn't able to trigger it for some reason, though.
Reviewed-by: Roland Scheidegger <srol...@vmware.com>
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