tests/spec/ext_framebuffer_multisample/draw-buffers-alpha-to-one.cpp

   1 /*
   2  * Copyright © 2012 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
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   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  */
  23
  24 #include "draw-buffers-common.h"
  25
  26 /**
  27  * \file draw-buffers-alpha-to-one.cpp
  28  *
  29  * Verify sample alpha to one with multiple draw buffers
  30  *
  31  * When rendering to multiple draw buffers, GL_SAMPLE_ALPHA_TO_ONE should
  32  * modify the alpha values sent to each draw buffer. OpenGL 3.3 specification's
  33  * section 4.1.3 (page 196 of pdf) is little unclear about the exact behavior
  34  * in above mentioned case:
  35  *
  36  * "All alpha values in this section refer only to the alpha component of the
  37  * fragment shader output linked to color number zero, index zero (see section
  38  * 3.9.2) if a fragment shader is in use, or the alpha component of the result
  39  * of fixed-function fragment shading. If the fragment shader does not write to
  40  * this output, the alpha value is undefined."
  41  *
  42  * And later in the same section it is stated that:
  43  *
  44  * "Next, if SAMPLE_ALPHA_TO_ONE is enabled, each alpha value is replaced by
  45  * the maximum representable alpha value for fixed-point color buffers, or by
  46  * 1.0 for floating-point buffers. Otherwise, the alpha values are not changed."
  47  *
  48  * By reading above two references together, specification seems to suggest that
  49  * alpha values for only draw buffer zero will be modified when GL_SAMPLE_TO_ONE.
  50  * is enabled. But with NVIDIA's proprietary drivers this test verifies that
  51  * alpha values for all the draw buffers will be modified. In my opinion, this
  52  * section needs clarification from khronos.
  53  *
  54  * At present test is based on the behavior observed with NVIDIA's proprietary
  55  * drivers.
  56  *
  57  * This test operates by drawing a pattern in multisample FBO to generate
  58  * reference and test images for all the draw buffers. Reference images are drawn
  59  * to right half of window system draw buffer and test images to left half.
  60  *
  61  * Compare the left and right halves of window system frame buffer to verify
  62  * the test image.
  63  *
  64  * Author: Anuj Phogat <anuj.phogat@gmail.com>
  65  */
  66
  67 PIGLIT_GL_TEST_CONFIG_BEGIN
  68
  69         config.supports_gl_compat_version = 10;
  70
  71         config.window_width = 512;
  72         config.window_height = 768;
  73         config.window_visual = PIGLIT_GL_VISUAL_DOUBLE | PIGLIT_GL_VISUAL_RGBA;
  74         config.khr_no_error_support = PIGLIT_NO_ERRORS;
  75
  76 PIGLIT_GL_TEST_CONFIG_END
  77
  78 static int samples;
  79
  80 void
  81 print_usage_and_exit(char *prog_name)
  82 {
  83         printf("Usage: %s <num_samples>\n", prog_name);
  84         piglit_report_result(PIGLIT_FAIL);
  85 }
  86
  87 void
  88 piglit_init(int argc, char **argv)
  89 {
  90         /* At present fragment shader supports only fixed number of
  91          * attachments (3)
  92          */
  93         int num_attachments = 3;
  94
  95         if (argc < 2)
  96                 print_usage_and_exit(argv[0]);
  97         {
  98                 char *endptr = NULL;
  99                 samples = strtol(argv[1], &endptr, 0);
 100                 if (endptr != argv[1] + strlen(argv[1]))
 101                         print_usage_and_exit(argv[0]);
 102         }
 103
 104         piglit_require_gl_version(21);
 105         piglit_require_extension("GL_ARB_framebuffer_object");
 106         piglit_require_extension("GL_ARB_vertex_array_object");
 107
 108         int pattern_width = piglit_width / 2;
 109         int pattern_height = piglit_height / num_attachments;
 110
 111         piglit_ortho_projection(pattern_width,
 112                                 pattern_height,
 113                                 GL_TRUE);
 114
 115         /* Skip the test if samples > GL_MAX_SAMPLES */
 116         GLint max_samples;
 117         glGetIntegerv(GL_MAX_SAMPLES, &max_samples);
 118
 119         if (samples > max_samples)
 120                 piglit_report_result(PIGLIT_SKIP);
 121
 122         ms_fbo_and_draw_buffers_setup(samples,
 123                                       pattern_width,
 124                                       pattern_height,
 125                                       num_attachments,
 126                                       GL_COLOR_BUFFER_BIT,
 127                                       GL_RGBA);
 128         shader_compile(false /* sample_alpha_to_coverage */,
 129                        false /* dual_src_blend */,
 130                        true /* frag_out_zero_write */);
 131 }
 132
 133 enum piglit_result
 134 piglit_display()
 135 {
 136         bool pass = true;
 137         glBindFramebuffer(GL_DRAW_FRAMEBUFFER, piglit_winsys_fbo);
 138         glClearColor(0.0, 0.0, 0.0, 1.0);
 139         glClear(GL_COLOR_BUFFER_BIT);
 140         allocate_data_arrays();
 141
 142         draw_reference_image(false /* sample_alpha_to_coverage */,
 143                              true /* sample_alpha_to_one */);
 144
 145         draw_test_image(false /* sample_alpha_to_coverage */,
 146                         true /* sample_alpha_to_one */);
 147
 148         pass = piglit_check_gl_error(GL_NO_ERROR) && pass;
 149
 150         glBindFramebuffer(GL_READ_FRAMEBUFFER, piglit_winsys_fbo);
 151         pass = piglit_probe_rect_halves_equal_rgba(0, 0,
 152                                                    piglit_width,
 153                                                    piglit_height)
 154                && pass;
 155
 156         /* Free the memory allocated for data arrays */
 157         free_data_arrays();
 158
 159         if (!piglit_automatic)
 160                 piglit_present_results();
 161
 162         return pass ? PIGLIT_PASS : PIGLIT_FAIL;
 163 }