[Piglit] [PATCH] fs-texelFetchOffset-2D: don't assume undefined values to be solid black

[Jose Fonseca]

Commmited.

Roland, please file a fdo bug requesting commit access for future changes.

Jose

----- Original Message -----
> From: Roland Scheidegger <sroland at vmware.com>
> 
> core GL specifies out-of-bound texel fetches return undefined
> results,
> except in a robust context with ARB_robust_buffer_access_behavior
> supported
> (which is core in 4.3), in which case texel fetch will return 0
> (OpenGL 4.3
> compatibility profile, page 387, subsection 11.1.3.2 Texel Fetches).
> Since the test requires neither robust context nor that extension it
> cannot
> assume any specific result value. In any case even returning zero is
> not what
> the test expected, since it wanted [0,0,0,1] instead.
> (With this change softpipe passes the test, as it clamps the coords.)
> 
> v2: fix black->undefined, formatting, comments
> ---
>  .../glsl-1.30/execution/fs-texelFetchOffset-2D.c   |   29
>  ++++++++++++++++----
>  1 file changed, 23 insertions(+), 6 deletions(-)
> 
> diff --git a/tests/spec/glsl-1.30/execution/fs-texelFetchOffset-2D.c
> b/tests/spec/glsl-1.30/execution/fs-texelFetchOffset-2D.c
> index 19e3654..8bdca7a 100644
> --- a/tests/spec/glsl-1.30/execution/fs-texelFetchOffset-2D.c
> +++ b/tests/spec/glsl-1.30/execution/fs-texelFetchOffset-2D.c
> @@ -76,7 +76,7 @@ piglit_display(void)
>  	bool pass = true;
>  	float red[4]   = {1.0, 0.0, 0.0, 1.0};
>  	float blue[4]  = {0.0, 0.0, 1.0, 1.0};
> -	float black[4] = {0.0, 0.0, 0.0, 1.0};
> +	float undefined[4] = {0.0, 0.0, 0.0, 0.0};
>  
>  	glClearColor(0.5, 0.5, 0.5, 1.0);
>  	glClear(GL_COLOR_BUFFER_BIT);
> @@ -92,12 +92,29 @@ piglit_display(void)
>  		for (q = 0; q < 4; q++) {
>  			const int tex_x = (q / 2) * ((width / 2));
>  			const int tex_y = (q % 2) * ((height / 2));
> -			float *c = black;
> +			float *c = undefined;
>  			const int x = 10+20*q;
>  
> -			/* fancy stuff - we should see red and blue
> -			   due to the offset for 3 levels,
> -			   otherwise we get lots of black border color */
> +			/* fancy stuff - we should see some red and blue
> +			 * due to the offset for 3 levels, all the rest is
> +			 * undefined due to out-of-bounds.
> +			 * Only with ARB_robust_buffer_access_behavior
> +			 * (and a robust context) the undefined result would
> +			 * be guaranteed to be zero instead.
> +			 *
> +			 * From the GL 3.0 spec, page 105 ("Texel Fetches"):
> +			 *
> +			 *     "The results of the texel fetch are
> +			 *      undefined if any of the following
> +			 *      conditions hold:
> +			 *
> +			 *      ...
> +			 *
> +			 *      - The texel coordinates refer to a
> +			 *        border texel outside of the defined
> +			 *        extents of the specified LOD"
> +			 */
> +
>  			if (l < 3) {
>  				if (q == 2) c = red;
>  				else if (q == 3) c = blue;
> @@ -107,7 +124,7 @@ piglit_display(void)
>  			piglit_Uniform2i(pos_location, tex_x, tex_y);
>  			piglit_draw_rect(x, y, 10, 10);
>  
> -			if (width > 2) /* below 1 wide no test */
> +			if (width > 2 && c != undefined) /* below 1 wide no test */
>  				pass &= piglit_probe_rect_rgba(x, y, 10, 10, c);
>  		}
>  	}
> --
> 1.7.9.5
> 
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