[Mesa-dev] [PATCH] mesa: check for no matrix change in _mesa_LoadMatrixf()

[Kenneth Graunke]

On Thursday, September 15, 2016 9:34:50 AM PDT Brian Paul wrote:
> Some apps issue redundant glLoadMatrixf() calls with the same matrix.
> Try to avoid setting dirty state in that situation.
> 
> This reduces the number of constant buffer updates by about half in
> ET Quake Wars.
> 
> Tested with Piglit, ETQW, Sauerbraten, Google Earth, etc.

                                                       ^^^
                               Is that a texture compression test suite?
                               :)

Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>

> ---
>  src/mesa/main/matrix.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/src/mesa/main/matrix.c b/src/mesa/main/matrix.c
> index b30b983..83f081e 100644
> --- a/src/mesa/main/matrix.c
> +++ b/src/mesa/main/matrix.c
> @@ -356,9 +356,11 @@ _mesa_LoadMatrixf( const GLfloat *m )
>            m[2], m[6], m[10], m[14],
>            m[3], m[7], m[11], m[15]);
>  
> -   FLUSH_VERTICES(ctx, 0);
> -   _math_matrix_loadf( ctx->CurrentStack->Top, m );
> -   ctx->NewState |= ctx->CurrentStack->DirtyFlag;
> +   if (memcmp(m, ctx->CurrentStack->Top->m, 16 * sizeof(GLfloat)) != 0) {
> +      FLUSH_VERTICES(ctx, 0);
> +      _math_matrix_loadf( ctx->CurrentStack->Top, m );
> +      ctx->NewState |= ctx->CurrentStack->DirtyFlag;
> +   }
>  }
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