[Mesa-dev] [PATCH 03/14] mesa: add begin_transform_feedback() helper

[Timothy Arceri]

On 24/08/17 23:21, Samuel Pitoiset wrote:
> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
> ---
>   src/mesa/main/transformfeedback.c | 49 ++++++++++++++++++++++++---------------
>   1 file changed, 30 insertions(+), 19 deletions(-)
> 
> diff --git a/src/mesa/main/transformfeedback.c b/src/mesa/main/transformfeedback.c
> index 307728c399..b217d0d84a 100644
> --- a/src/mesa/main/transformfeedback.c
> +++ b/src/mesa/main/transformfeedback.c
> @@ -381,22 +381,22 @@ get_xfb_source(struct gl_context *ctx)
>   }
>   
>   
> -void GLAPIENTRY
> -_mesa_BeginTransformFeedback(GLenum mode)
> +static ALWAYS_INLINE void
> +begin_transform_feedback(struct gl_context *ctx, GLenum mode, bool no_error)
>   {
>      struct gl_transform_feedback_object *obj;
>      struct gl_transform_feedback_info *info = NULL;
> +   struct gl_program *source;
>      GLuint i;
>      unsigned vertices_per_prim;
> -   GET_CURRENT_CONTEXT(ctx);
>   
>      obj = ctx->TransformFeedback.CurrentObject;
>   
>      /* Figure out what pipeline stage is the source of data for transform
>       * feedback.
>       */
> -   struct gl_program *source = get_xfb_source(ctx);
> -   if (source == NULL) {
> +   source = get_xfb_source(ctx);


Personally I would rather this left as is. We no longer have to bend to 
MCVSs refusal to support C99 for so many years.


> +   if (!no_error && source == NULL) {
>         _mesa_error(ctx, GL_INVALID_OPERATION,
>                     "glBeginTransformFeedback(no program active)");
>         return;
> @@ -404,7 +404,7 @@ _mesa_BeginTransformFeedback(GLenum mode)
>   
>      info = source->sh.LinkedTransformFeedback;
>   
> -   if (info->NumOutputs == 0) {
> +   if (!no_error && info->NumOutputs == 0) {
>         _mesa_error(ctx, GL_INVALID_OPERATION,
>                     "glBeginTransformFeedback(no varyings to record)");
>         return;
> @@ -421,23 +421,26 @@ _mesa_BeginTransformFeedback(GLenum mode)
>         vertices_per_prim = 3;
>         break;
>      default:
> -      _mesa_error(ctx, GL_INVALID_ENUM, "glBeginTransformFeedback(mode)");
> +      if (!no_error)
> +         _mesa_error(ctx, GL_INVALID_ENUM, "glBeginTransformFeedback(mode)");

You should be able to make this something like:

if (!no_error) {
    _mesa_error(ctx, GL_INVALID_ENUM, "glBeginTransformFeedback(mode)");
    return;
} else {
    /* Stop compiler warnings */
    unreachable("Error in API use when using KHR_no_error");
}



>         return;
>      }
>   
> -   if (obj->Active) {
> -      _mesa_error(ctx, GL_INVALID_OPERATION,
> -                  "glBeginTransformFeedback(already active)");
> -      return;
> -   }
> +   if (!no_error) {
> +      if (obj->Active) {
> +         _mesa_error(ctx, GL_INVALID_OPERATION,
> +                     "glBeginTransformFeedback(already active)");
> +         return;
> +      }
>   
> -   for (i = 0; i < ctx->Const.MaxTransformFeedbackBuffers; i++) {
> -      if ((info->ActiveBuffers >> i) & 1) {
> -         if (obj->BufferNames[i] == 0) {
> -            _mesa_error(ctx, GL_INVALID_OPERATION,
> -                        "glBeginTransformFeedback(binding point %d does not "
> -                        "have a buffer object bound)", i);
> -            return;
> +      for (i = 0; i < ctx->Const.MaxTransformFeedbackBuffers; i++) {
> +         if ((info->ActiveBuffers >> i) & 1) {
> +            if (obj->BufferNames[i] == 0) {
> +               _mesa_error(ctx, GL_INVALID_OPERATION,
> +                           "glBeginTransformFeedback(binding point %d does not "
> +                           "have a buffer object bound)", i);
> +               return;
> +            }
>            }
>         }
>      }
> @@ -472,6 +475,14 @@ _mesa_BeginTransformFeedback(GLenum mode)
>   }
>   
>   
> +void GLAPIENTRY
> +_mesa_BeginTransformFeedback(GLenum mode)
> +{
> +   GET_CURRENT_CONTEXT(ctx);
> +   begin_transform_feedback(ctx, mode, false);
> +}
> +
> +
>   void GLAPIENTRY
>   _mesa_EndTransformFeedback(void)
>   {
>