[Mesa-dev] [PATCH] mesa: don't map depth+stencil buffer twice in glReadPixels()

[Vadim Girlin]

On Wed, 2011-11-16 at 20:41 +0400, Vadim Girlin wrote:
> On Wed, 2011-11-16 at 07:53 -0700, Brian Paul wrote:
> > In slow_read_depth_stencil_pixels_separate() we might have separate
> > depth and stencil buffers or a combined buffer.  In the later case,
> > don't map the buffer twice.  This function is used when the depth
> > scale/bias pixel transfer values are not the defaults.
> > 
> > Fixes http://bugs.freedesktop.org/show_bug.cgi?id=42963
> > ---
> >  src/mesa/main/readpix.c |   14 +++++++++++---
> >  1 files changed, 11 insertions(+), 3 deletions(-)
> > 
> > diff --git a/src/mesa/main/readpix.c b/src/mesa/main/readpix.c
> > index 8550618..0b41de6 100644
> > --- a/src/mesa/main/readpix.c
> > +++ b/src/mesa/main/readpix.c
> > @@ -402,10 +402,16 @@ slow_read_depth_stencil_pixels_separate(struct gl_context *ctx,
> >     GLubyte *depthMap, *stencilMap;
> >     int depthStride, stencilStride, j;
> >  
> > +   /* The depth and stencil buffers might be separate, or a single buffer.
> > +    * If one buffer, only map it once.
> > +    */
> >     ctx->Driver.MapRenderbuffer(ctx, depthRb, x, y, width, height,
> >  			       GL_MAP_READ_BIT, &depthMap, &depthStride);
> > -   ctx->Driver.MapRenderbuffer(ctx, stencilRb, x, y, width, height,
> > -			       GL_MAP_READ_BIT, &stencilMap, &stencilStride);
> > +   if (stencilRb != depthRb) {
> > +      ctx->Driver.MapRenderbuffer(ctx, stencilRb, x, y, width, height,
> > +                                  GL_MAP_READ_BIT, &stencilMap,
> > +                                  &stencilStride);
> > +   }
> >  
> 
> Probably we want the following here:
> 
>    else
>       stencilMap = depthMap;
> 
> 

And I also forgot stencilStride.

Vadim

> Vadim
> 
> >     for (j = 0; j < height; j++) {
> >        GLubyte stencilVals[MAX_WIDTH];
> > @@ -424,7 +430,9 @@ slow_read_depth_stencil_pixels_separate(struct gl_context *ctx,
> >     }
> >  
> >     ctx->Driver.UnmapRenderbuffer(ctx, depthRb);
> > -   ctx->Driver.UnmapRenderbuffer(ctx, stencilRb);
> > +   if (stencilRb != depthRb) {
> > +      ctx->Driver.UnmapRenderbuffer(ctx, stencilRb);
> > +   }
> >  }
> >  
> > 
> 
> 
>