[Mesa-dev] [PATCH 2/6] mesa: Fix GL error generation in glBlitFramebuffer()

[Kenneth Graunke]

On 12/12/2012 03:25 PM, Anuj Phogat wrote:
> Signed-off-by: Anuj Phogat <anuj.phogat at gmail.com>
> ---
>   src/mesa/main/fbobject.c |   10 +++++++++-
>   1 files changed, 9 insertions(+), 1 deletions(-)
>
> diff --git a/src/mesa/main/fbobject.c b/src/mesa/main/fbobject.c
> index 4b7d4ab..9e32836 100644
> --- a/src/mesa/main/fbobject.c
> +++ b/src/mesa/main/fbobject.c
> @@ -2856,7 +2856,15 @@ _mesa_BlitFramebuffer(GLint srcX0, GLint srcY0, GLint srcX1, GLint srcY1,
>   	 mask &= ~GL_STENCIL_BUFFER_BIT;
>         }
>         else if (_mesa_get_format_bits(readRb->Format, GL_STENCIL_BITS) !=
> -	       _mesa_get_format_bits(drawRb->Format, GL_STENCIL_BITS)) {
> +               _mesa_get_format_bits(drawRb->Format, GL_STENCIL_BITS) ||
> +               /* OpenGL/ES specification is not very clear about it. But GLES3
> +                * conformance test expects GL_INVALID_OPERATION in case of below
> +                * listed combination of formats for read/draw buffers.
> +                */
> +               (readRb->InternalFormat == GL_DEPTH32F_STENCIL8 &&
> +                drawRb->InternalFormat == GL_DEPTH24_STENCIL8) ||
> +               (readRb->InternalFormat == GL_DEPTH24_STENCIL8 &&
> +                drawRb->InternalFormat == GL_DEPTH32F_STENCIL8)) {
>   	 /* There is no need to check the stencil datatype here, because
>   	  * there is only one: GL_UNSIGNED_INT.
>   	  */

I found this text:

 From the OpenGL 3.0 spec, section 4.3 (page 277):
"Calling BlitFramebuffer will result in an INVALID_OPERATION error if 
mask includes DEPTH_BUFFER_BIT or STENCIL_BUFFER_BIT, and the source and 
destination depth and stencil buffer formats do not match."

This text also appears in the ES 3.0 and GL 4.2 specs.

I believe the existing code's interpretation of this paragraph was:

   - if DEPTH_BUFFER_BIT is set, source & destination depth buffer 
formats must match.
   - if STENCIL_BUFFER_BIT is set, source & destination stencil buffer 
formats must match.

An alternate interpretation that might appease those tests is:

   - if *either* DEPTH_BUFFER_BIT or STENCIL_BUFFER_BIT is set, both the 
depth *and* stencil formats must match.

If that's the case, you can simply check readRb->Format == 
drawRb->Format.  It seems reasonable to me, at least for packed formats.