[Mesa-dev] [PATCH] mesa: error out in indirect draw when vertex bindings mismatch

[Fredrik Höglund]

On Tuesday 17 November 2015, Tapani Pälli wrote:
> 
> On 11/16/2015 08:55 AM, Tapani Pälli wrote:
> >
> >
> > On 11/13/2015 07:18 PM, Fredrik Höglund wrote:
> >> On Friday 13 November 2015, Tapani Pälli wrote:
> >>> Patch adds additional mask for tracking which vertex buffer bindings
> >>> are set. This array can be directly compared to which vertex arrays
> >>> are enabled and should match when drawing.
> >>>
> >>> Fixes following CTS tests:
> >>>
> >>>     ES31-CTS.draw_indirect.negative-noVBO-arrays
> >>>     ES31-CTS.draw_indirect.negative-noVBO-elements
> >>>
> >>> Signed-off-by: Tapani Pälli <tapani.palli at intel.com>
> >>> ---
> >>>   src/mesa/main/api_validate.c | 13 +++++++++++++
> >>>   src/mesa/main/mtypes.h       |  3 +++
> >>>   src/mesa/main/varray.c       |  5 +++++
> >>>   3 files changed, 21 insertions(+)
> >>>
> >>> diff --git a/src/mesa/main/api_validate.c b/src/mesa/main/api_validate.c
> >>> index a490189..e82e89a 100644
> >>> --- a/src/mesa/main/api_validate.c
> >>> +++ b/src/mesa/main/api_validate.c
> >>> @@ -710,6 +710,19 @@ valid_draw_indirect(struct gl_context *ctx,
> >>>         return GL_FALSE;
> >>>      }
> >>>
> >>> +   /* From OpenGL ES 3.1 spec. section 10.5:
> >>> +    *     "An INVALID_OPERATION error is generated if zero is bound to
> >>> +    *     VERTEX_ARRAY_BINDING, DRAW_INDIRECT_BUFFER or to any enabled
> >>> +    *     vertex array."
> >>> +    *
> >>> +    * Here we check that vertex buffer bindings match with enabled
> >>> +    * vertex arrays.
> >>> +    */
> >>> +   if (ctx->Array.VAO->_Enabled != ctx->Array.VAO->VertexBindingMask) {
> >>
> >> This test only works when the enabled vertex arrays are associated with
> >> their default vertex buffer binding points.
> >
> > Could you open up this more, is there some existing test or app that
> > would do this? Would be great for testing purposes, all the indirect
> > draw rendering CTS tests pass with this change.
> 
> Sorry, the question does not make sense. What I meant is that do you 
> know some app that would fail this test to help debugging/fixing the issue?

No, but the following example should trigger the problem:

/* Enable arrays 0 and 1 */
glEnableVertexAttribArray(0);
glEnableVertexAttribArray(1);

/* Make both arrays use VBO binding point #0 */
glVertexAttribBinding(0, 0);
glVertexAttribBinding(1, 0);

/* Bind a buffer object to VBO binding point #0 */
glBindVertexBuffer(0, ...);

/* Bind a draw indirect buffer */
glBindBuffer(GL_DRAW_INDIRECT_BUFFER, ...);

/* This call will now generate an INVALID_OPERATION error since
 * no buffer is bound to VBO binding point #1, even though none
 * of the enabled arrays use it.
 */
glDrawArraysIndirect(...);

> >
> >>> +      _mesa_error(ctx, GL_INVALID_OPERATION, "%s(No VBO bound)", name);
> >>> +      return GL_FALSE;
> >>> +   }
> >>> +
> >>>      if (!_mesa_valid_prim_mode(ctx, mode, name))
> >>>         return GL_FALSE;
> >>>
> >>> diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
> >>> index 4efdf1e..6c6187f 100644
> >>> --- a/src/mesa/main/mtypes.h
> >>> +++ b/src/mesa/main/mtypes.h
> >>> @@ -1419,6 +1419,9 @@ struct gl_vertex_array_object
> >>>      /** Vertex buffer bindings */
> >>>      struct gl_vertex_buffer_binding VertexBinding[VERT_ATTRIB_MAX];
> >>>
> >>> +   /** Mask indicating which binding points are set. */
> >>> +   GLbitfield64 VertexBindingMask;
> >>> +
> >>>      /** Mask of VERT_BIT_* values indicating which arrays are
> >>> enabled */
> >>>      GLbitfield64 _Enabled;
> >>>
> >>> diff --git a/src/mesa/main/varray.c b/src/mesa/main/varray.c
> >>> index 887d0c0..0a94c5a 100644
> >>> --- a/src/mesa/main/varray.c
> >>> +++ b/src/mesa/main/varray.c
> >>> @@ -174,6 +174,11 @@ bind_vertex_buffer(struct gl_context *ctx,
> >>>         binding->Offset = offset;
> >>>         binding->Stride = stride;
> >>>
> >>> +      if (vbo == ctx->Shared->NullBufferObj)
> >>> +         vao->VertexBindingMask &= ~VERT_BIT(index);
> >>> +      else
> >>> +         vao->VertexBindingMask |= VERT_BIT(index);
> >>> +
> >>>         vao->NewArrays |= binding->_BoundArrays;
> >>>      }
> >>>   }
> >>>
> >>
> > _______________________________________________
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>