[Piglit] [PATCH 2/2] ext_framebuffer_multisample: Add a test for alpha to coverage with no draw buffer zero write

[Brian Paul]

On 11/02/2016 03:36 PM, Anuj Phogat wrote:
> In a situation when there are multiple render targets with alpha to
> coverage enabled, if fragment shader doesn't write to draw buffer
> zero, alpha value used for coverage will be undefined. Such case
> should not cause a GPU hang.
>
> Signed-off-by: Anuj Phogat <anuj.phogat at gmail.com>
> ---
> Not everything in allocate_data_arrays() is useful for this test
> case. But additional allocations don't hurt as we're freeing all
> of them later in free_data_arrays(). Using these functions is
> simply convenient to write multiple draw buffers tests.
> ---
>   .../ext_framebuffer_multisample/CMakeLists.gl.txt  |   2 +
>   ...alpha-to-coverage-no-draw-buffer-zero-write.cpp | 134 +++++++++++++++++++++
>   2 files changed, 136 insertions(+)
>   create mode 100644 tests/spec/ext_framebuffer_multisample/alpha-to-coverage-no-draw-buffer-zero-write.cpp
>
> diff --git a/tests/spec/ext_framebuffer_multisample/CMakeLists.gl.txt b/tests/spec/ext_framebuffer_multisample/CMakeLists.gl.txt
> index 944a93e..6841267 100644
> --- a/tests/spec/ext_framebuffer_multisample/CMakeLists.gl.txt
> +++ b/tests/spec/ext_framebuffer_multisample/CMakeLists.gl.txt
> @@ -11,6 +11,8 @@ link_libraries (
>   piglit_add_executable (ext_framebuffer_multisample-accuracy common.cpp accuracy.cpp)
>   piglit_add_executable (ext_framebuffer_multisample-alpha-to-coverage-no-draw-buffer-zero common.cpp
>   		       draw-buffers-common.cpp alpha-to-coverage-no-draw-buffer-zero.cpp)
> +piglit_add_executable (ext_framebuffer_multisample-alpha-to-coverage-no-draw-buffer-zero-write common.cpp
> +		       draw-buffers-common.cpp alpha-to-coverage-no-draw-buffer-zero-write.cpp)
>   piglit_add_executable (ext_framebuffer_multisample-alpha-to-coverage-dual-src-blend common.cpp
>   		       draw-buffers-common.cpp alpha-to-coverage-dual-src-blend.cpp)
>   piglit_add_executable (ext_framebuffer_multisample-alpha-to-one-dual-src-blend common.cpp
> diff --git a/tests/spec/ext_framebuffer_multisample/alpha-to-coverage-no-draw-buffer-zero-write.cpp b/tests/spec/ext_framebuffer_multisample/alpha-to-coverage-no-draw-buffer-zero-write.cpp
> new file mode 100644
> index 0000000..a6150bd
> --- /dev/null
> +++ b/tests/spec/ext_framebuffer_multisample/alpha-to-coverage-no-draw-buffer-zero-write.cpp
> @@ -0,0 +1,134 @@
> +/*
> + * Copyright © 2016 Intel Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + */
> +
> +#include "draw-buffers-common.h"
> +
> +/**
> + * \file alpha-to-coverage-no-draw-buffer-zero-write.cpp
> + *
> + * Verify sample alpha to coverage with multiple draw buffers when nothing
> + * is written to draw buffer zero.
> + *
> + * When nothing is written to draw buffer zero, GL_SAMPLE_ALPHA_TO_COVERAGE
> + * usage shouldn't hang the system. The alpha value used to determine
> + * coverage will be undefined which will result in to pixels with undefined
> + * colors. So, pixels can't be probed for color in this test.
> + *
> + * From OpenGL 2.1 specification:
> + * "If a fragment shader writes to neither gl FragColor nor gl FragData,
> + * the values of the fragment colors following shader execution are
> + * undefined, and may differ for each fragment color."
> + *
> + * It is a significant edge case for i965 driver.
> + */
> +
> +PIGLIT_GL_TEST_CONFIG_BEGIN
> +
> +	config.supports_gl_compat_version = 21;
> +
> +	config.window_width = 512;
> +	config.window_height = 768;
> +	config.window_visual = PIGLIT_GL_VISUAL_DOUBLE | PIGLIT_GL_VISUAL_RGBA;
> +
> +PIGLIT_GL_TEST_CONFIG_END
> +
> +void
> +print_usage_and_exit(char *prog_name)
> +{
> +        printf("Usage: %s <num_samples>\n", prog_name);
> +	piglit_report_result(PIGLIT_FAIL);

Indentation is off there.


> +}
> +
> +void
> +piglit_init(int argc, char **argv)
> +{
> +	int samples;
> +	/* At present fragment shader supports only fixed number of
> +	 * attachments (3)
> +	 */
> +	int num_attachments = 3;
> +
> +	if (argc < 2)
> +		print_usage_and_exit(argv[0]);
> +	{
> +		char *endptr = NULL;

This looks a little funny at first.  Maybe insert an empty line before 
the start of the { block.  Actually, do we really need strtol() here? 
Wouldn't atoi() do the job?

> +		samples = strtol(argv[1], &endptr, 0);
> +		if (endptr != argv[1] + strlen(argv[1]))
> +			print_usage_and_exit(argv[0]);
> +	}
> +
> +	piglit_require_extension("GL_ARB_framebuffer_object");
> +	piglit_require_extension("GL_ARB_vertex_array_object");
> +	piglit_require_extension("GL_EXT_framebuffer_multisample");
> +
> +	int pattern_width = piglit_width / 2;
> +	int pattern_height = piglit_height / num_attachments;
> +
> +	piglit_ortho_projection(pattern_width,
> +				pattern_height,
> +				GL_TRUE);
> +
> +	/* Skip the test if samples > GL_MAX_SAMPLES */
> +	GLint max_samples;
> +	glGetIntegerv(GL_MAX_SAMPLES, &max_samples);
> +
> +	if (samples < 1 || samples > max_samples)
> +		piglit_report_result(PIGLIT_SKIP);
> +
> +	ms_fbo_and_draw_buffers_setup(samples,
> +				      pattern_width,
> +				      pattern_height,
> +				      num_attachments,
> +				      GL_COLOR_BUFFER_BIT,
> +				      GL_RGBA /* color_buffer_zero_format */);
> +	shader_compile(true /* sample_alpha_to_coverage */,
> +		       false /* dual_src_blend */,
> +		       false /* frag_out_zero_write */);
> +}
> +
> +enum piglit_result
> +piglit_display()
> +{
> +	bool pass = true;

You don't need to init pass here since it's always assigned below.
I'd insert a blank line here too.

> +	glBindFramebuffer(GL_DRAW_FRAMEBUFFER, piglit_winsys_fbo);
> +	glClearColor(0.0, 0.0, 0.0, 1.0);
> +	glClear(GL_COLOR_BUFFER_BIT);
> +	allocate_data_arrays();
> +
> +	draw_test_image(true /* sample_alpha_to_coverage */,
> +			false /* sample_alpha_to_one */);
> +
> +	pass = piglit_check_gl_error(GL_NO_ERROR) && pass;
> +
> +	/* Free the memory allocated for data arrays */
> +	free_data_arrays();
> +
> +	if (!piglit_automatic)
> +		piglit_present_results();
> +
> +	/* The fragment colors are undefined in this test. So, we can't probe
> +	 * the pixels. If test executes to completion without error, return
> +	 * PIGLIT_PASS.
> +	 */
> +	return pass ? PIGLIT_PASS : PIGLIT_FAIL;
> +}
>

Looks good otherwise.  For both,
Reviewed-by: Brian Paul <brianp at vmware.com>