[Mesa-dev] [PATCH] softpipe: fix clamping when using unormalized coordinates

[Brian Paul]

On 11/13/2011 03:24 AM, Morgan Armand wrote:
> ---
>   src/gallium/drivers/softpipe/sp_tex_sample.c |    7 ++++---
>   1 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/src/gallium/drivers/softpipe/sp_tex_sample.c b/src/gallium/drivers/softpipe/sp_tex_sample.c
> index 72629a0..9b0e54e1 100644
> --- a/src/gallium/drivers/softpipe/sp_tex_sample.c
> +++ b/src/gallium/drivers/softpipe/sp_tex_sample.c
> @@ -491,7 +491,8 @@ wrap_linear_unorm_clamp(const float s[4], unsigned size,
>      uint ch;
>      for (ch = 0; ch<  4; ch++) {
>         /* Not exactly what the spec says, but it matches NVIDIA output */
> -      float u = CLAMP(s[ch] - 0.5F, 0.0f, (float) size - 1.0f);
> +      float u = CLAMP(s[ch], 0.0f, (float) size);
> +      u -= 0.5F;
>         icoord0[ch] = util_ifloor(u);

If s=0, then icoord0 = -1 and that's not right.  The 'i' coordinates 
must be in the range [0,size-1].

Are you trying to fix a specific bug or piglit test?


>         icoord1[ch] = icoord0[ch] + 1;
>         w[ch] = frac(u);
> @@ -512,8 +513,8 @@ wrap_linear_unorm_clamp_to_border(const float s[4], unsigned size,
>         u -= 0.5F;
>         icoord0[ch] = util_ifloor(u);
>         icoord1[ch] = icoord0[ch] + 1;
> -      if (icoord1[ch]>  (int) size - 1)
> -         icoord1[ch] = size - 1;
> +      if (icoord1[ch]>  (int) size)
> +         icoord1[ch] = size;
>         w[ch] = frac(u);
>      }
>   }

-Brian