[Mesa-dev] [PATCH 2/2] mesa: clamp viewport values only once when using glViewport()

[Nicolai Hähnle]

On 28.07.2017 15:47, Samuel Pitoiset wrote:
> It's useless to clamp the same values for all viewports.
> 
> +7% in the "viewport change" test (drawoverhead benchmark).
> 
> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>

I think it would be cleaner to call clamp_viewport in all callers of 
set_viewport_no_notify. Fewer boolean function args is better and 
clearer in my book.

With that changed, the patch is

Reviewed-by: Nicolai Hähnle <nicolai.haehnle at amd.com>


> ---
>   src/mesa/main/viewport.c | 36 ++++++++++++++++++++++++------------
>   1 file changed, 24 insertions(+), 12 deletions(-)
> 
> diff --git a/src/mesa/main/viewport.c b/src/mesa/main/viewport.c
> index e6004bad40..1cff4d846e 100644
> --- a/src/mesa/main/viewport.c
> +++ b/src/mesa/main/viewport.c
> @@ -36,13 +36,12 @@
>   #include "viewport.h"
>   
>   static void
> -set_viewport_no_notify(struct gl_context *ctx, unsigned idx,
> -                       GLfloat x, GLfloat y,
> -                       GLfloat width, GLfloat height)
> +clamp_viewport(struct gl_context *ctx, GLfloat *x, GLfloat *y,
> +               GLfloat *width, GLfloat *height)
>   {
>      /* clamp width and height to the implementation dependent range */
> -   width  = MIN2(width, (GLfloat) ctx->Const.MaxViewportWidth);
> -   height = MIN2(height, (GLfloat) ctx->Const.MaxViewportHeight);
> +   *width  = MIN2(*width, (GLfloat) ctx->Const.MaxViewportWidth);
> +   *height = MIN2(*height, (GLfloat) ctx->Const.MaxViewportHeight);
>   
>      /* The GL_ARB_viewport_array spec says:
>       *
> @@ -55,11 +54,20 @@ set_viewport_no_notify(struct gl_context *ctx, unsigned idx,
>      if (ctx->Extensions.ARB_viewport_array ||
>          (ctx->Extensions.OES_viewport_array &&
>           _mesa_is_gles31(ctx))) {
> -      x = CLAMP(x,
> -                ctx->Const.ViewportBounds.Min, ctx->Const.ViewportBounds.Max);
> -      y = CLAMP(y,
> -                ctx->Const.ViewportBounds.Min, ctx->Const.ViewportBounds.Max);
> +      *x = CLAMP(*x,
> +                 ctx->Const.ViewportBounds.Min, ctx->Const.ViewportBounds.Max);
> +      *y = CLAMP(*y,
> +                 ctx->Const.ViewportBounds.Min, ctx->Const.ViewportBounds.Max);
>      }
> +}
> +
> +static void
> +set_viewport_no_notify(struct gl_context *ctx, unsigned idx,
> +                       GLfloat x, GLfloat y,
> +                       GLfloat width, GLfloat height, bool clamped)
> +{
> +   if (!clamped)
> +      clamp_viewport(ctx, &x, &y, &width, &height);
>   
>      if (ctx->ViewportArray[idx].X == x &&
>          ctx->ViewportArray[idx].Width == width &&
> @@ -89,6 +97,10 @@ static void
>   viewport(struct gl_context *ctx, GLint x, GLint y, GLsizei width,
>            GLsizei height)
>   {
> +   /* Clamp the viewport to the implementation dependent values. */
> +   clamp_viewport(ctx, (GLfloat *)&x, (GLfloat *)&y,
> +                  (GLfloat *)&width, (GLfloat *)&height);
> +
>      /* The GL_ARB_viewport_array spec says:
>       *
>       *     "Viewport sets the parameters for all viewports to the same values
> @@ -101,7 +113,7 @@ viewport(struct gl_context *ctx, GLint x, GLint y, GLsizei width,
>       * signal the driver once at the end.
>       */
>      for (unsigned i = 0; i < ctx->Const.MaxViewports; i++)
> -      set_viewport_no_notify(ctx, i, x, y, width, height);
> +      set_viewport_no_notify(ctx, i, x, y, width, height, true);
>   
>      if (ctx->Driver.Viewport)
>         ctx->Driver.Viewport(ctx);
> @@ -153,7 +165,7 @@ void
>   _mesa_set_viewport(struct gl_context *ctx, unsigned idx, GLfloat x, GLfloat y,
>                       GLfloat width, GLfloat height)
>   {
> -   set_viewport_no_notify(ctx, idx, x, y, width, height);
> +   set_viewport_no_notify(ctx, idx, x, y, width, height, false);
>   
>      if (ctx->Driver.Viewport)
>         ctx->Driver.Viewport(ctx);
> @@ -165,7 +177,7 @@ viewport_array(struct gl_context *ctx, GLuint first, GLsizei count,
>   {
>      for (GLsizei i = 0; i < count; i++) {
>         set_viewport_no_notify(ctx, i + first, inputs[i].X, inputs[i].Y,
> -                             inputs[i].Width, inputs[i].Height);
> +                             inputs[i].Width, inputs[i].Height, false);
>      }
>   
>      if (ctx->Driver.Viewport)
> 


-- 
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Aber vergiss niemals, wie sie sein sollte.