[Mesa-dev] [PATCH 7/8] mesa: fix assertion in _mesa_drawbuffers()

[Roland Scheidegger]

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-stable at 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?

Roland