Reviewed-by: Marek Olšák <mar...@gmail.com>
Marek
On Wed, Dec 14, 2011 at 6:00 PM, Paul Berry <stereotype...@gmail.com> wrote:
> This patch adds two new fields to the gl_transform_feedback_info
> struct:
>
> - BufferStride records the total number of components (per vertex)
> that transform feedback is being instructed to store in each buffer.
>
> - Outputs[i].DstOffset records the offset within the interleaved
> structure of each transform feedback output.
>
> These values are needed by the i965 gen6 and r600g back-ends, so it
> seems better to have the linker provide them rather than force each
> back-end to compute them independently.
>
> Also, DstOffset helps pave the way for supporting
> ARB_transform_feedback3, which allows the transform feedback output to
> contain holes between attributes by specifying
> gl_SkipComponents{1,2,3,4} as the varying name.
> ---
> src/glsl/linker.cpp | 5 ++++-
> src/mesa/main/mtypes.h | 10 ++++++++++
> 2 files changed, 14 insertions(+), 1 deletions(-)
>
> diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
> index b8a7126..6587008 100644
> --- a/src/glsl/linker.cpp
> +++ b/src/glsl/linker.cpp
> @@ -1598,7 +1598,9 @@ tfeedback_decl::store(struct gl_shader_program *prog,
> info->Outputs[info->NumOutputs].OutputRegister = this->location + v;
> info->Outputs[info->NumOutputs].NumComponents = this->vector_elements;
> info->Outputs[info->NumOutputs].OutputBuffer = buffer;
> + info->Outputs[info->NumOutputs].DstOffset = info->BufferStride[buffer];
> ++info->NumOutputs;
> + info->BufferStride[buffer] += this->vector_elements;
> }
> return true;
> }
> @@ -1863,7 +1865,8 @@ store_tfeedback_info(struct gl_context *ctx, struct
> gl_shader_program *prog,
> tfeedback_decl *tfeedback_decls)
> {
> unsigned total_tfeedback_components = 0;
> - prog->LinkedTransformFeedback.NumOutputs = 0;
> + memset(&prog->LinkedTransformFeedback, 0,
> + sizeof(prog->LinkedTransformFeedback));
> for (unsigned i = 0; i < num_tfeedback_decls; ++i) {
> unsigned buffer =
> prog->TransformFeedback.BufferMode == GL_SEPARATE_ATTRIBS ? i : 0;
> diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
> index 1934349..e18c5f8 100644
> --- a/src/mesa/main/mtypes.h
> +++ b/src/mesa/main/mtypes.h
> @@ -1821,7 +1821,17 @@ struct gl_transform_feedback_info {
> unsigned OutputRegister;
> unsigned OutputBuffer;
> unsigned NumComponents;
> +
> + /** offset (in DWORDs) of this output within the interleaved structure
> */
> + unsigned DstOffset;
> } Outputs[MAX_PROGRAM_OUTPUTS];
> +
> + /**
> + * Total number of components stored in each buffer. This may be used by
> + * hardware back-ends to determine the correct stride when interleaving
> + * multiple transform feedback outputs in the same buffer.
> + */
> + unsigned BufferStride[MAX_FEEDBACK_ATTRIBS];
> };
>
> /**
> --
> 1.7.6.4
>
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