[Mesa-dev] [PATCH] st/mesa: DrawTFB should use the vertex count from the last call of EndTFB

[Brian Paul]

On 12/17/2011 06:41 AM, Marek Olšák wrote:
>  From ARB_transform_feedback2:
>      ... the vertex count used for the rendering operation is
>      set by the previous EndTransformFeedback command.
> ---
>   src/mesa/state_tracker/st_cb_xformfb.c |   53 +++++++++++++++++++++++++------
>   1 files changed, 42 insertions(+), 11 deletions(-)
>
> diff --git a/src/mesa/state_tracker/st_cb_xformfb.c b/src/mesa/state_tracker/st_cb_xformfb.c
> index 2fc28dc..e699fb6 100644
> --- a/src/mesa/state_tracker/st_cb_xformfb.c
> +++ b/src/mesa/state_tracker/st_cb_xformfb.c
> @@ -55,6 +55,11 @@ struct st_transform_feedback_object {
>
>      unsigned num_targets;
>      struct pipe_stream_output_target *targets[PIPE_MAX_SO_BUFFERS];
> +
> +   /* This encapsulates the count that can be used as a source for draw_vbo.
> +    * It contains a stream output target from the last call of
> +    * EndTransformFeedback. */
> +   struct pipe_stream_output_target *draw_count;
>   };
>
>
> @@ -81,6 +86,8 @@ st_delete_transform_feedback(struct gl_context *ctx,
>            (struct st_transform_feedback_object*)obj;
>      unsigned i;
>
> +   pipe_so_target_reference(&sobj->draw_count, NULL);
> +
>      /* Unreference targets. */
>      for (i = 0; i<  sobj->num_targets; i++) {
>         pipe_so_target_reference(&sobj->targets[i], NULL);
> @@ -115,6 +122,7 @@ st_begin_transform_feedback(struct gl_context *ctx, GLenum mode,
>         if (bo) {
>            /* Check whether we need to recreate the target. */
>            if (!sobj->targets[i] ||
> +             sobj->targets[i] == sobj->draw_count ||
>                sobj->targets[i]->buffer != bo->buffer ||
>                sobj->targets[i]->buffer_offset != sobj->base.Offset[i] ||
>                sobj->targets[i]->buffer_size != sobj->base.Size[i]) {
> @@ -141,7 +149,7 @@ st_begin_transform_feedback(struct gl_context *ctx, GLenum mode,
>
>
>   static void
> -st_stop_transform_feedback(struct gl_context *ctx,
> +st_pause_transform_feedback(struct gl_context *ctx,
>                              struct gl_transform_feedback_object *obj)
>   {
>      struct st_context *st = st_context(ctx);
> @@ -161,11 +169,9 @@ st_resume_transform_feedback(struct gl_context *ctx,
>                             ~0);
>   }
>
> -/* Set count_from_stream_output to any stream output target
> - * from the transform feedback object. */
> -void
> -st_transform_feedback_draw_init(struct gl_transform_feedback_object *obj,
> -                                struct pipe_draw_info *out)
> +
> +static struct pipe_stream_output_target *
> +st_transform_feedback_get_draw_target(struct gl_transform_feedback_object *obj)
>   {
>      struct st_transform_feedback_object *sobj =
>            (struct st_transform_feedback_object*)obj;
> @@ -173,13 +179,38 @@ st_transform_feedback_draw_init(struct gl_transform_feedback_object *obj,
>
>      for (i = 0; i<  Elements(sobj->targets); i++) {
>         if (sobj->targets[i]) {
> -         out->count_from_stream_output = sobj->targets[i];
> -         return;
> +         return sobj->targets[i];
>         }
>      }
>
>      assert(0);
> -   out->count_from_stream_output = NULL;
> +   return NULL;
> +}
> +
> +
> +static void
> +st_end_transform_feedback(struct gl_context *ctx,
> +                          struct gl_transform_feedback_object *obj)
> +{
> +   struct st_context *st = st_context(ctx);
> +   struct st_transform_feedback_object *sobj =
> +         (struct st_transform_feedback_object*)obj;
> +
> +   cso_set_stream_outputs(st->cso_context, 0, NULL, 0);
> +
> +   pipe_so_target_reference(&sobj->draw_count,
> +                            st_transform_feedback_get_draw_target(obj));
> +}
> +
> +
> +void
> +st_transform_feedback_draw_init(struct gl_transform_feedback_object *obj,
> +                                struct pipe_draw_info *out)
> +{
> +   struct st_transform_feedback_object *sobj =
> +         (struct st_transform_feedback_object*)obj;
> +
> +   out->count_from_stream_output = sobj->draw_count;
>   }

Minor nit: instead of using casts for st_transform_feedback_object, 
define a cast wrapper as we do for other types:

static INLINE struct st_transform_feedback_object *
st_transform_feedback_object(struct gl_transform_feedback_object *obj)
{
    return (struct st_transform_feedback_object *) obj;
}


Looks good otherwise.


>
> @@ -189,8 +220,8 @@ st_init_xformfb_functions(struct dd_function_table *functions)
>      functions->NewTransformFeedback = st_new_transform_feedback;
>      functions->DeleteTransformFeedback = st_delete_transform_feedback;
>      functions->BeginTransformFeedback = st_begin_transform_feedback;
> -   functions->EndTransformFeedback = st_stop_transform_feedback;
> -   functions->PauseTransformFeedback = st_stop_transform_feedback;
> +   functions->EndTransformFeedback = st_end_transform_feedback;
> +   functions->PauseTransformFeedback = st_pause_transform_feedback;
>      functions->ResumeTransformFeedback = st_resume_transform_feedback;
>   }
>