[Mesa-dev] [PATCH v2 04/23] glsl: Assign GLSL StreamIds to transform feedback outputs.

[Ian Romanick]

On 06/18/2014 02:51 AM, Iago Toral Quiroga wrote:
> Inter-shader outputs must be on stream 0, which is the default.
> ---
>  src/glsl/link_varyings.cpp | 12 +++++++++---
>  src/glsl/link_varyings.h   |  7 +++++++
>  2 files changed, 16 insertions(+), 3 deletions(-)
> 
> diff --git a/src/glsl/link_varyings.cpp b/src/glsl/link_varyings.cpp
> index f765d37..9725a43 100644
> --- a/src/glsl/link_varyings.cpp
> +++ b/src/glsl/link_varyings.cpp
> @@ -291,6 +291,7 @@ tfeedback_decl::init(struct gl_context *ctx, const void *mem_ctx,
>     this->skip_components = 0;
>     this->next_buffer_separator = false;
>     this->matched_candidate = NULL;
> +   this->stream_id = 0;
>  
>     if (ctx->Extensions.ARB_transform_feedback3) {
>        /* Parse gl_NextBuffer. */
> @@ -355,8 +356,8 @@ tfeedback_decl::is_same(const tfeedback_decl &x, const tfeedback_decl &y)
>  
>  
>  /**
> - * Assign a location for this tfeedback_decl object based on the transform
> - * feedback candidate found by find_candidate.
> + * Assign a location and stream ID for this tfeedback_decl object based on the
> + * transform feedback candidate found by find_candidate.
>   *
>   * If an error occurs, the error is reported through linker_error() and false
>   * is returned.
> @@ -437,6 +438,11 @@ tfeedback_decl::assign_location(struct gl_context *ctx,
>        return false;
>     }
>  
> +   /* Only transform feedback varyings can be assigned to non-zero streams,
> +    * so assign the stream id here.
> +    */
> +   this->stream_id = this->matched_candidate->toplevel_var->data.stream;
> +
>     return true;
>  }
>  
> @@ -495,7 +501,7 @@ tfeedback_decl::store(struct gl_context *ctx, struct gl_shader_program *prog,
>        info->Outputs[info->NumOutputs].ComponentOffset = location_frac;
>        info->Outputs[info->NumOutputs].OutputRegister = location;
>        info->Outputs[info->NumOutputs].NumComponents = output_size;
> -      info->Outputs[info->NumOutputs].StreamId = 0;
> +      info->Outputs[info->NumOutputs].StreamId = stream_id;
>        info->Outputs[info->NumOutputs].OutputBuffer = buffer;
>        info->Outputs[info->NumOutputs].DstOffset = info->BufferStride[buffer];
>        ++info->NumOutputs;
> diff --git a/src/glsl/link_varyings.h b/src/glsl/link_varyings.h
> index 6fa2681..4e485c3 100644
> --- a/src/glsl/link_varyings.h
> +++ b/src/glsl/link_varyings.h
> @@ -210,6 +210,13 @@ private:
>      * data structure that was found.  Otherwise NULL.
>      */
>     const tfeedback_candidate *matched_candidate;
> +
> +   /**
> +    * StreamId assigned to this varying (defaults to 0). Can only be set to
> +    * values other than 0 in geometry shaders that use the stream layout
> +    * modifier. Accepted values must be in the range [0, MAX_VERTEX_STREAMS].

MAX_VERTEX_STREAMS-1, right?

> +    */
> +   unsigned stream_id;
>  };
>  
>  
>