[Piglit] [PATCH] ext_framebuffer_multisample: add --alpha-to-one option to coverage test

[Roland Scheidegger]

I think should mention that the reference probably isn't quite right (if
I try it here, the reference is the same with or without alpha-to-one,
but with nvidia with alpha-to-one it's a bit different (darker) than
without). I think it's because the reference drawing doesn't really take
into account that the samples which get written thanks to
coverage-to-alpha also had their alpha values changed to 1.0, but I
could be wrong and maybe it is correct after all...

In any case,
Reviewed-by: Roland Scheidegger <sroland at vmware.com>

Am 04.08.2017 um 19:03 schrieb Brian Paul:
> Alpha-to-one only makes sense when used with alpha-to-coverage.  This
> patch adds a flag to the alpha-to-coverage test to exercise alpha-to-one.
> This will fail with drivers which emulate alpha-to-one in the FS.
> ---
>  tests/all.py                                                  |  4 ++++
>  .../ext_framebuffer_multisample/sample-alpha-to-coverage.cpp  | 11 ++++++++---
>  2 files changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/tests/all.py b/tests/all.py
> index ae55425..abe6185 100644
> --- a/tests/all.py
> +++ b/tests/all.py
> @@ -3044,6 +3044,10 @@ with profile.test_list.group_manager(
>                 sample_count, buffer_type],
>                'sample-alpha-to-coverage {} {}'.format(
>                    sample_count, buffer_type))
> +            g(['ext_framebuffer_multisample-sample-alpha-to-coverage',
> +               sample_count, buffer_type, '--alpha-to-one'],
> +              'sample-alpha-to-coverage-alpha-to-one {} {}'.format(
> +                  sample_count, buffer_type))
>  
>          for test in ['line-smooth', 'point-smooth', 'polygon-smooth',
>                       'sample-alpha-to-one',
> diff --git a/tests/spec/ext_framebuffer_multisample/sample-alpha-to-coverage.cpp b/tests/spec/ext_framebuffer_multisample/sample-alpha-to-coverage.cpp
> index 7b756ba..32b4161 100644
> --- a/tests/spec/ext_framebuffer_multisample/sample-alpha-to-coverage.cpp
> +++ b/tests/spec/ext_framebuffer_multisample/sample-alpha-to-coverage.cpp
> @@ -54,11 +54,12 @@ PIGLIT_GL_TEST_CONFIG_BEGIN
>  PIGLIT_GL_TEST_CONFIG_END
>  
>  static GLenum buffer_to_test;
> +static bool alpha_to_one = false;
>  
>  void
>  print_usage_and_exit(char *prog_name)
>  {
> -	printf("Usage: %s <num_samples> <test_type>\n"
> +	printf("Usage: %s <num_samples> <test_type> [--alpha-to-one]\n"
>  	       "  where <test_type> is one of:\n"
>  	       "    color\n"
>  	       "    depth\n",
> @@ -93,6 +94,10 @@ piglit_init(int argc, char **argv)
>  	} else
>  		print_usage_and_exit(argv[0]);
>  
> +	if (argc == 4 && strcmp(argv[3], "--alpha-to-one") == 0) {
> +		alpha_to_one = true;
> +	}
> +
>  	int pattern_width = piglit_width / 2;
>  	int pattern_height = piglit_height / num_attachments;
>  
> @@ -133,10 +138,10 @@ piglit_display()
>  	 */
>  	if(buffer_to_test == GL_COLOR_BUFFER_BIT)
>  		draw_reference_image(true /* sample_alpha_to_coverage */,
> -				     false /* sample_alpha_to_one */);
> +				     alpha_to_one);
>  
>  	draw_test_image(true /* sample_alpha_to_coverage */,
> -			false /* sample_alpha_to_one */);
> +			alpha_to_one);
>  
>  	pass = piglit_check_gl_error(GL_NO_ERROR) && pass;
>  
>