[Piglit] [PATCH 2/2] Add test to verify sample alpha to coverage with multisample fbo

Paul Berry stereotype441 at gmail.com
Fri Jun 22 14:40:48 PDT 2012


On 20 June 2012 19:01, Anuj Phogat <anuj.phogat at gmail.com> wrote:

> This test varifies that with GL_SAMPLE_ALPHA_TO_COVERAGE enabled, the
> coverage
> value is set by fragment alpha value. Coverage value decides the number of
> samples in multisample buffer covered by an incoming fragment, which
> receive
> the fragment data.
>
> It also includes testing of GL_SAMPLE_ALPHA_TO_COVERAGE with
> GL_SAMPLE_ALPHA_TO_ONE
> enabled.
>
> V2: Add testing for coverage values which may result in dithering for all
> sample
>    counts. Dropping the testing for multisample depth buffer.
>

This patch is:

Reviewed-by: Paul Berry <stereotype441 at gmail.com>


>
> Signed-off-by: Anuj Phogat <anuj.phogat at gmail.com>
> ---
> This test fails on AMD's catalyst drivers with GL_SAMPLE_ALPHA_TO_ONE
> enabled. But
> as I remember it passed on NVIDIA last time. I will confirm it before
> pushing the
> test case.
>
>  tests/all.tests                                    |    6 +
>  .../ext_framebuffer_multisample/CMakeLists.gl.txt  |    1 +
>  .../sample-alpha-to-coverage.cpp                   |  412
> ++++++++++++++++++++
>  3 files changed, 419 insertions(+), 0 deletions(-)
>  create mode 100644
> tests/spec/ext_framebuffer_multisample/sample-alpha-to-coverage.cpp
>
> diff --git a/tests/all.tests b/tests/all.tests
> index 5fdc9e7..6745037 100644
> --- a/tests/all.tests
> +++ b/tests/all.tests
> @@ -1391,6 +1391,12 @@ for num_samples in (2, 4, 8, 16, 32):
>                  test_name)
>         ext_framebuffer_multisample[test_name] = PlainExecTest(executable)
>
> +for num_samples in (2, 4, 8, 16, 32):
> +        test_name = ' '.join(['sample-alpha-to-coverage',
> str(num_samples)])
> +        executable = 'ext_framebuffer_multisample-{0} -auto'.format(
> +                test_name)
> +        ext_framebuffer_multisample[test_name] = PlainExecTest(executable)
> +
>  ext_framebuffer_object = Group()
>  spec['EXT_framebuffer_object'] = ext_framebuffer_object
>  add_fbo_stencil_tests(ext_framebuffer_object, 'GL_STENCIL_INDEX1')
> diff --git a/tests/spec/ext_framebuffer_multisample/CMakeLists.gl.txt
> b/tests/spec/ext_framebuffer_multisample/CMakeLists.gl.txt
> index c746328..c6566be 100644
> --- a/tests/spec/ext_framebuffer_multisample/CMakeLists.gl.txt
> +++ b/tests/spec/ext_framebuffer_multisample/CMakeLists.gl.txt
> @@ -29,6 +29,7 @@ piglit_add_executable
> (ext_framebuffer_multisample-renderbuffer-samples renderbu
>  piglit_add_executable
> (ext_framebuffer_multisample-renderbufferstorage-samples
> renderbufferstorage-samples.c)
>  piglit_add_executable (ext_framebuffer_multisample-samples samples.c)
>  piglit_add_executable (ext_framebuffer_multisample-sample-coverage
> common.cpp sample-coverage.cpp)
> +piglit_add_executable
> (ext_framebuffer_multisample-sample-alpha-to-coverage common.cpp
> sample-alpha-to-coverage.cpp)
>  piglit_add_executable (ext_framebuffer_multisample-turn-on-off common.cpp
> turn-on-off.cpp)
>  piglit_add_executable (ext_framebuffer_multisample-unaligned-blit
> common.cpp unaligned-blit.cpp)
>  piglit_add_executable (ext_framebuffer_multisample-upsample common.cpp
> upsample.cpp)
> diff --git
> a/tests/spec/ext_framebuffer_multisample/sample-alpha-to-coverage.cpp
> b/tests/spec/ext_framebuffer_multisample/sample-alpha-to-coverage.cpp
> new file mode 100644
> index 0000000..540396b
> --- /dev/null
> +++ b/tests/spec/ext_framebuffer_multisample/sample-alpha-to-coverage.cpp
> @@ -0,0 +1,412 @@
> +/*
> + * Copyright © 2012 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 "common.h"
> +
> +/**
> + * \file sample-alpha-to-coverage.cpp
> + *
> + * Verify GL_SAMPLE_ALPHA_TO_COVERAGE with multisample FBO.
> + *
> + * This test operates by drawing a test pattern to multisample_fbo with
> + * GL_SAMPLE_ALPHA_TO_COVERAGE disabled.
> + *
> + * Blit the multisample_fbo to top half of window system framebuffer. This
> + * is used as reference image to visually compare the difference caused by
> + * sample alpha to coverage value.
> + *
> + * Compute the expected color values based on the coverage value used to
> + * draw the test pattern.
> + *
> + * Clear the multisample framebuffer to a unique color. Draw the same test
> + * pattern in multisample buffer with GL_SAMPLE_ALPHA_TO_COVERAGE enabled.
> + * Resolve the multisample FBO by  blitting it to a single sample FBO.
> Blit
> + * the resolve_fbo to bottom half of window system framebuffer. This is
> our
> + * test image.
> + *
> + * Probe the rectangles in bottom half of window system framebuffer and
> + * compare with expected color values. OpenGL 3.0 specification intends
> + * to allow (but not require) the implementation to produce a dithering
> + * effect when the coverage value is not a strict multiple of
> 1/num_samples.
> + * We will skip computing expected values and probing for such rectangles.
> + * They are drawn just to look for dithering by human inspection.
> + *
> + * Repeat the above testing with GL_SAMPLE_ALPHA_TO_ONE enabled /
> disabled.
> + * when both GL_SAMPLE_ALPHA_TO_ONE and GL_SAMPLE_ALPHA_TO_COVERAGE are
> + * enabled, GL_SAMPLE_ALPHA_TO_COVERAGE takes effect first. i.e. the
> + * coverage value is computed from the alpha value before the alpha value
> + * is changed to 1.
> + *
> + * Note: glSampleCoverage() takes effect in the graphics pipeline before
> + * the point where the output of the fragment shader is split into the
> + * various buffers. So it's very likely that if glSampleCoverage() works
> + * properly for color buffers, it will work properly for depth and stencil
> + * buffers too.
> + *
> + * Author: Anuj Phogat <anuj.phogat at gmail.com>
> + */
> +
> +int piglit_width = 512; int piglit_height = 256;
> +int piglit_window_mode = GLUT_DOUBLE | GLUT_RGBA | GLUT_ALPHA ;
> +const int pattern_width = 512; const int pattern_height = 128;
> +
> +static Fbo ms_fbo, resolve_fbo;
> +static GLbitfield buffer_to_test;
> +
> +static float *coverage = NULL;
> +static float *color = NULL;
> +static float *expected = NULL;
> +
> +static int num_samples;
> +static int num_rects;
> +static int prog;
> +static int color_loc;
> +static int depth_loc;
> +
> +static const float bg_color[4] = { 0.4, 0.6, 0.0, 0.8 };
> +
> +static const char *vert =
> +       "#version 130\n"
> +       "in vec2 pos;\n"
> +       "uniform float depth;\n"
> +       "void main()\n"
> +       "{\n"
> +       "  vec4 eye_pos = gl_ModelViewProjectionMatrix * vec4(pos, 0.0,
> 1.0);\n"
> +       "  gl_Position = vec4(eye_pos.xy, depth, 1.0);\n"
> +       "}\n";
> +
> +static const char *frag =
> +       "#version 130\n"
> +       "uniform vec4 color;\n"
> +       "void main()\n"
> +       "{\n"
> +       "  gl_FragColor = color;\n"
> +       "}\n";
> +
> +void
> +shader_compile()
> +{
> +       /* Compile program */
> +       GLint vs = piglit_compile_shader_text(GL_VERTEX_SHADER, vert);
> +       GLint fs = piglit_compile_shader_text(GL_FRAGMENT_SHADER, frag);
> +       prog = piglit_link_simple_program(vs, fs);
> +
> +       if (!piglit_link_check_status(prog)) {
> +               piglit_report_result(PIGLIT_FAIL);
> +       }
> +
> +       glBindAttribLocation(prog, 0, "pos");
> +       glEnableVertexAttribArray(0);
> +
> +       /* Set up uniforms */
> +       glUseProgram(prog);
> +       color_loc = glGetUniformLocation(prog, "color");
> +       depth_loc = glGetUniformLocation(prog, "depth");
> +}
> +
> +void
> +draw_pattern(bool sample_alpha_to_coverage, bool sample_alpha_to_one)
> +{
> +       glUseProgram(prog);
> +       glClearColor(bg_color[0], bg_color[1],
> +                    bg_color[2], bg_color[3]);
> +       glClear(buffer_to_test);
> +
> +       if (sample_alpha_to_coverage)
> +               glEnable (GL_SAMPLE_ALPHA_TO_COVERAGE);
> +
> +       if (sample_alpha_to_one)
> +               glEnable (GL_SAMPLE_ALPHA_TO_ONE);
> +
> +       unsigned int indices[6] = {0, 1, 2, 0, 2, 3};
> +
> +       for (int i = 0; i < num_rects; ++i) {
> +
> +               float vertex_data[4][2] = {
> +               { 0.0f + i * (pattern_width / num_rects),   0.0f
> },
> +               { 0.0f + i * (pattern_width / num_rects),   pattern_height
> },
> +               { (i + 1.0f) * (pattern_width / num_rects), pattern_height
> },
> +               { (i + 1.0f) * (pattern_width / num_rects), 0.0f
> } };
> +
> +               glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE,
> +                                     sizeof(vertex_data[0]),
> +                                     (void *) vertex_data);
> +
> +               glUniform4fv(color_loc, 1, (color + i * 4));
> +               glUniform1f(depth_loc, 0.0f);
> +               glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT,
> +                              (void *) indices);
> +       }
> +       if (sample_alpha_to_coverage)
> +               glDisable (GL_SAMPLE_ALPHA_TO_COVERAGE);
> +
> +       if (sample_alpha_to_one)
> +               glDisable (GL_SAMPLE_ALPHA_TO_ONE);
> +}
> +
> +void
> +print_usage_and_exit(char *prog_name)
> +{
> +       printf("Usage: %s <num_samples>\n", prog_name);
> +       piglit_report_result(PIGLIT_FAIL);
> +}
> +
> +void
> +compute_expected(bool sample_alpha_to_one)
> +{
> +       int i, j;
> +
> +       /* Sample alpha to coverage doesn't affect single sample FBO */
> +       if(num_samples == 0) {
> +               for(i = 0; i < 4; i++)
> +                       expected[i] = color[i];
> +               return;
> +       }
> +
> +       /* Fragment's alpha value is directly used as coverage value */
> +       for (i = 0; i < num_rects; i++)
> +               coverage[i] = color[i * 4 + 3];
> +
> +       /* Coverage value decides the number of samples in multisample
> buffer
> +        * covered by an incoming fragment, which will then receive the
> fragment
> +        * data. When the multisample buffer is resolved it will be blended
> +        * with the background color which will be written to the remaining
> +        * samples.
> +        * Page 254 (page 270 of the PDF) of the OpenGL 3.0 spec says:
> +        * "The method of combination is not specified, though a simple
> average
> +        * computed independently for each color component is recommended."
> +        */
> +       if(buffer_to_test == GL_COLOR_BUFFER_BIT) {
> +               for (i = 0; i < num_rects; i++) {
> +
> +                       float samples_used = coverage[i] * num_samples;
> +                       /* Exepected color values are computed only for
> integer
> +                        * number of samples_used
> +                        */
> +                       if(samples_used == (int)samples_used) {
> +
> +                               for(j =0; j < 4; j++)
> +                                       expected[i * 4 + j] =
> +                                       color[i * 4 + j] * coverage[i] +
> +                                       bg_color[j] * (1 - coverage[i]);
> +
> +                               if (sample_alpha_to_one)
> +                                       expected[i * 4 + 3] =
> +                                       1.0 * coverage[i] +
> +                                       bg_color[3] * (1 - coverage[i]);
> +                       }
> +               }
> +       }
> +}
> +
> +bool
> +probe_framebuffer_color(bool sample_alpha_to_one)
> +{
> +       bool result = true;
> +       glBindFramebuffer(GL_READ_FRAMEBUFFER, 0);
> +
> +       for (int i = 0; i < num_rects; i++) {
> +               float samples_used = coverage[i] * num_samples;
> +
> +               /* Only probe rectangles with coverage value which is a
> strict
> +                *  multiple of 1 / num_samples.
> +                */
> +               if(samples_used == (int)samples_used) {
> +                       result = piglit_probe_rect_rgba(
> +                                i * (pattern_width / num_rects),
> +                                0,
> +                                pattern_width / num_rects,
> +                                pattern_height,
> +                                expected + i * 4)
> +                                && result;
> +               }
> +       }
> +       return result;
> +}
> +
> +bool
> +test_sample_alpha_to_coverage(bool sample_alpha_to_one)
> +{
> +       bool result = true;
> +       compute_expected(sample_alpha_to_one);
> +
> +       /* Draw test pattern in multisample ms_fbo with
> +        * GL_SAMPLE_ALPHA_TO_COVERAGE enabled
> +        */
> +       glBindFramebuffer(GL_DRAW_FRAMEBUFFER, ms_fbo.handle);
> +       draw_pattern(true /* sample_alpha_to_coverage */ ,
> sample_alpha_to_one);
> +
> +       /* Blit ms_fbo to resolve_fbo to resolve multisample buffer */
> +       glBindFramebuffer(GL_READ_FRAMEBUFFER, ms_fbo.handle);
> +       glBindFramebuffer(GL_DRAW_FRAMEBUFFER, resolve_fbo.handle);
> +       glBlitFramebuffer(0, 0, pattern_width, pattern_height,
> +                         0, 0, pattern_width, pattern_height,
> +                         buffer_to_test, GL_NEAREST);
> +
> +       /* Blit resolve_fbo to the bottom half of window system
> framebuffer.
> +        * This is the test image.
> +        */
> +       glBindFramebuffer(GL_READ_FRAMEBUFFER, resolve_fbo.handle);
> +       glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
> +       glBlitFramebuffer(0, 0, pattern_width, pattern_height,
> +                         0, 0, pattern_width, pattern_height,
> +                         buffer_to_test, GL_NEAREST);
> +
> +       /* Probe the bottom half of default framebuffer and compare to the
> +        * expected values */
> +       if (buffer_to_test == GL_COLOR_BUFFER_BIT)
> +               result = probe_framebuffer_color(sample_alpha_to_one) &&
> result;
> +
> +       result = piglit_check_gl_error(GL_NO_ERROR) && result;
> +       return result;
> +}
> +
> +void
> +allocate_data_arrays(void)
> +{
> +       /* Draw 2N + 1 rectangles for N samples, each with a unique color
> +        * and coverage value
> +        */
> +       num_rects = 2 * num_samples + 1;
> +
> +       /* Allocate data arrays based on number of samples used */
> +       color = (float *) malloc(num_rects * 4 * sizeof(float));
> +       coverage = (float *) malloc(num_rects * sizeof(float));
> +       expected = (float *) malloc(num_rects * 4 * sizeof(float));
> +
> +       for(int i = 0; i < num_rects; i++) {
> +               /* Randomly select color for each rectangle */
> +               color[i * 4 + 0] = (rand() % 1000) * .001;
> +               color[i * 4 + 1] = (rand() % 1000) * .001;
> +               color[i * 4 + 2] = (rand() % 1000) * .001;
> +               /* Alpha value will be used as coverage */
> +               color[i * 4 + 3] = i * (1.0 / (2 * num_samples));
> +       }
> +}
> +
> +void
> +free_data_arrays(void)
> +{
> +       if(color != NULL) {
> +               free(color);
> +               color = NULL;
> +       }
> +       if(coverage != NULL) {
> +               free(coverage);
> +               coverage = NULL;
> +       }
> +       if(expected != NULL) {
> +               free(expected);
> +               expected = NULL;
> +       }
> +}
> +
> +void
> +piglit_init(int argc, char **argv)
> +{
> +       int samples;
> +       if (argc < 2)
> +               print_usage_and_exit(argv[0]);
> +       {
> +               char *endptr = NULL;
> +               samples = strtol(argv[1], &endptr, 0);
> +               if (endptr != argv[1] + strlen(argv[1]))
> +                       print_usage_and_exit(argv[0]);
> +       }
> +
> +       piglit_require_gl_version(30);
> +       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 > max_samples)
> +               piglit_report_result(PIGLIT_SKIP);
> +
> +       /* Setup frame buffer objects with required configuration */
> +       ms_fbo.setup(FboConfig(samples, pattern_width, pattern_height));
> +       resolve_fbo.setup(FboConfig(0, pattern_width, pattern_height));
> +
> +        if (!piglit_check_gl_error(GL_NO_ERROR)) {
> +               printf("Error setting up frame buffer objects\n");
> +               piglit_report_result(PIGLIT_FAIL);
> +        }
> +
> +       /* Query the number of samples used in ms_fbo. OpenGL
> implementation
> +        * may create FBO with more samples per pixel than what is
> requested.
> +        */
> +       glBindRenderbuffer(GL_RENDERBUFFER, ms_fbo.color_rb);
> +       glGetRenderbufferParameteriv(GL_RENDERBUFFER,
> +                                    GL_RENDERBUFFER_SAMPLES,
> +                                    &num_samples);
> +
> +       buffer_to_test = GL_COLOR_BUFFER_BIT;
> +       shader_compile();
> +}
> +
> +enum piglit_result
> +piglit_display()
> +{
> +       bool pass = true;
> +       allocate_data_arrays();
> +
> +       glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
> +       glClearColor(0.0, 0.0, 0.0, 1.0);
> +       glClear(buffer_to_test);
> +
> +       /* Draw test pattern in multisample ms_fbo with
> +        * GL_SAMPLE_ALPHA_TO_COVERAGE disabled.
> +        */
> +       glBindFramebuffer(GL_DRAW_FRAMEBUFFER, ms_fbo.handle);
> +       ms_fbo.set_viewport();
> +       draw_pattern(false /* sample_alpha_to_coverage */,
> +                    false /* sample_alpha_to_one */ );
> +
> +       /* Blit ms_fbo to the top half of window system framebuffer. This
> +        * is our reference image to visually compare the effect of MSAA
> +        * with sample alpha to coverage.
> +        */
> +       glBindFramebuffer(GL_READ_FRAMEBUFFER, ms_fbo.handle);
> +       glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
> +       glBlitFramebuffer(0, 0,
> +                         pattern_width, pattern_height,
> +                         0, pattern_height,
> +                         pattern_width, 2 * pattern_height,
> +                         buffer_to_test, GL_NEAREST);
> +
> +       /* Test with sample_alpha_to_one = false */
> +       pass = test_sample_alpha_to_coverage(false) && pass;
> +
> +       /* Test sample alpha to coverage with sample_alpha_to_one = true */
> +       pass = test_sample_alpha_to_coverage(true) && pass;
> +
> +       /* Free the memory allocated for data arrays */
> +       free_data_arrays();
> +
> +       if (!piglit_automatic &&
> +           buffer_to_test != GL_DEPTH_BUFFER_BIT)
> +               piglit_present_results();
> +
> +       return pass ? PIGLIT_PASS : PIGLIT_FAIL;
> +}
> --
> 1.7.7.6
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/piglit/attachments/20120622/61294f20/attachment-0001.html>


More information about the Piglit mailing list