[Piglit] [PATCH] Add a test for viewport triangle clipping.

[Brian Paul]

On 11/14/2012 03:30 PM, Stuart Abercrombie wrote:
> Triangles should be clipped to the clip volume and therefore shouldn't end up being rasterized outside the viewport.
>
> This was failing on Sandy Bridge with guard band clipping enabled.
>
> v2 with a new name, more comments and addition to all.tests.
>
> v3 with Eric's comments incorporated, and the explicit window size removed.
> ---
>   tests/all.tests                             |    1 +
>   tests/general/CMakeLists.gl.txt             |    1 +
>   tests/general/triangle-guardband-viewport.c |   77 +++++++++++++++++++++++++++
>   3 files changed, 79 insertions(+), 0 deletions(-)
>   create mode 100644 tests/general/triangle-guardband-viewport.c
>
> diff --git a/tests/all.tests b/tests/all.tests
> index 306473b..6b4c2e5 100644
> --- a/tests/all.tests
> +++ b/tests/all.tests
> @@ -556,6 +556,7 @@ add_plain_test(gl11, 'streaming-texture-leak')
>   add_plain_test(gl11, 'texredefine')
>   add_plain_test(gl11, 'texsubimage')
>   add_plain_test(gl11, 'texture-al')
> +add_concurrent_test(gl11, 'triangle-guardband-viewport')
>
>   gl10 = Group()
>   spec['!OpenGL 1.0'] = gl10
> diff --git a/tests/general/CMakeLists.gl.txt b/tests/general/CMakeLists.gl.txt
> index 0a5cd11..efaa56e 100644
> --- a/tests/general/CMakeLists.gl.txt
> +++ b/tests/general/CMakeLists.gl.txt
> @@ -137,5 +137,6 @@ piglit_add_executable (occlusion-query-discard occlusion-query-discard.c)
>   piglit_add_executable (quad-invariance quad-invariance.c)
>   piglit_add_executable (clear-accum clear-accum.c)
>   piglit_add_executable (vs-point_size-zero vs-point_size-zero.c)
> +piglit_add_executable (triangle-guardband-viewport triangle-guardband-viewport.c)
>
>   # vim: ft=cmake:
> diff --git a/tests/general/triangle-guardband-viewport.c b/tests/general/triangle-guardband-viewport.c
> new file mode 100644
> index 0000000..6a99f30
> --- /dev/null
> +++ b/tests/general/triangle-guardband-viewport.c
> @@ -0,0 +1,77 @@
> +/* Copyright 2012 Google Inc.
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, write to the Free Software
> + * Foundation Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
> + *
> + * Authors:
> + *   Stuart Abercrombie<sabercrombie at google.com>
> +*/
> +
> +/** @file triangle-guardband-vewport.c
> + *
> + * Tests whether clipping of triangles to the clip volume
> + * is reflected in what is rasterized. Specifically,
> + * triangles (unlike some other primitives) should not be
> + * rasterized outside the viewport extents because they should
> + * have been clipped to the clip volume mapping to the viewport.
> + *
> + * Faulty guard-band clipping optimizations have been known to
> + * not honor this requirement.
> + */
> +
> +#include "piglit-util-gl-common.h"
> +
> +PIGLIT_GL_TEST_CONFIG_BEGIN
> +
> +	config.supports_gl_compat_version = 10;
> +
> +	config.window_visual = PIGLIT_GL_VISUAL_DOUBLE | PIGLIT_GL_VISUAL_RGB;
> +
> +PIGLIT_GL_TEST_CONFIG_END
> +
> +enum piglit_result
> +piglit_display(void)
> +{
> +	bool pass = true;
> +	static float green[] = {0.0, 1.0, 0.0, 0.0};
> +	static float blue[]  = {0.0, 0.0, 1.0, 0.0};
> +
> +	/* make the whole window green. */
> +	glClearColor(0.0, 1.0, 0.0, 0.0);
> +	glClear(GL_COLOR_BUFFER_BIT);
> +
> +	/* set viewport to the left half of the window */
> +	glViewport(0, 0, piglit_width / 2, piglit_height);
> +
> +	/* draw blue rect extending beyond the right edge of the
> +	   frustrum, notionally across the whole window
> +	*/
> +	glColor4fv(blue);
> +	piglit_draw_rect(-1.0, -1.0, 4.0, 2.0);
> +
> +	/* check that the right half of the window, outside
> +	   the viewport, still has the clear color
> +	*/
> +	pass&= (bool)piglit_probe_rect_rgb(piglit_width/2, 0,

I don't think you need to use &= here and we haven't bothered with the 
cast in other tests.

Unrelated: we should probably change piglit_probe_XXX() to return bool 
instead of int.


> +			    piglit_width/2, piglit_height, green);
> +
> +	piglit_present_results();
> +
> +	return pass ? PIGLIT_PASS : PIGLIT_FAIL;
> +}
> +
> +void
> +piglit_init(int argc, char **argv)
> +{
> +}

Looks good otherwise.

Reviewed-by: Brian Paul <brianp at vmware.com>