tests/general/triangle-rasterization-overdraw.cpp

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  27
  28 /**
  29  * Triangle Rasterization Overdraw Test
  30  *
  31  * Draws a triangle fan to fill the screen and ensures every pixel was drawn only once
  32  * Based on idea from Brian Paul
  33  *
  34  *
  35  * Contains two methods of drawing to cover both clipped and unclipped triangles:
  36  *
  37  *   1. No-Clip: Picks a random point in the window and walks the perimeter of the window
  38  *               adding vertices to the triangle fan at non integer steps.
  39  *
  40  *   2. Clip:    Picks a random point in the window and adds vertices to the triangle fan
  41  *               around a circle that contains the entire window, thus going off screen.
  42  */
  43
  44 #include "piglit-util-gl.h"
  45 #include "mersenne.hpp"
  46
  47 #include <time.h>
  48 #include <vector>
  49 #include <algorithm>
  50
  51 /* Data structures */
  52 struct Vector
  53 {
  54         Vector()
  55                 : x(0), y(0)
  56         {
  57         }
  58
  59         Vector(float x, float y)
  60                 : x(x), y(y)
  61         {
  62         }
  63
  64         float x, y;
  65 };
  66
  67 /* Command line arguments */
  68 bool rect = false;
  69 bool clips = false;
  70 bool break_on_fail = false;
  71 int random_test_count = 10;
  72
  73 /* Piglit variables */
  74
  75 PIGLIT_GL_TEST_CONFIG_BEGIN
  76
  77         config.supports_gl_compat_version = 10;
  78
  79         config.window_width = 1000;
  80         config.window_height = 1000;
  81         config.window_visual = PIGLIT_GL_VISUAL_RGB | PIGLIT_GL_VISUAL_DOUBLE;
  82         config.khr_no_error_support = PIGLIT_NO_ERRORS;
  83
  84 PIGLIT_GL_TEST_CONFIG_END
  85
  86 /* Globals */
  87 int test_id = 0;
  88 Mersenne mersenne;
  89
  90
  91 /* Random floating point number between 0 and 1. */
  92 static inline float
  93 random_float(void)
  94 {
  95         const int float_range = 1 << 23;
  96         return (mersenne.value() % float_range) * (1.0 / float_range);
  97 }
  98
  99 /* Random float from [a to b) */
 100 static inline float
 101 random_float(float a, float b)
 102 {
 103         return a + (b - a - 1) * random_float();
 104 }
 105
 106
 107 struct TestCase
 108 {
 109         Vector mid;
 110         std::vector<Vector> triangle_fan;
 111
 112         struct {
 113                 int x;
 114                 int y;
 115                 int w;
 116                 int h;
 117         } probe_rect;
 118
 119         void generate(void);
 120         bool run(void) const;
 121 };
 122
 123
 124 /* Generates a random triangle fan with a random origin, and contouring a rectangle or circle */
 125 void TestCase::generate(void)
 126 {
 127         /* Random center point */
 128         if (clips) {
 129                 mid.x = random_float(-0.5*piglit_width, 1.5*piglit_width);
 130                 mid.y = random_float(-0.5*piglit_height, 1.5*piglit_height);
 131         } else {
 132                 mid.x = random_float(0, piglit_width);
 133                 mid.y = random_float(0, piglit_height);
 134         }
 135
 136         if (clips) {
 137                 probe_rect.x = 0;
 138                 probe_rect.y = 0;
 139                 probe_rect.w = piglit_width;
 140                 probe_rect.h = piglit_height;
 141         } else {
 142                 probe_rect.x = piglit_width/4;
 143                 probe_rect.y = piglit_height/4;
 144                 probe_rect.w = piglit_width/2;
 145                 probe_rect.h = piglit_height/2;
 146         }
 147
 148         triangle_fan.clear();
 149         triangle_fan.push_back(mid);
 150
 151         if (rect) {
 152                 /* Step around the window perimeter adding triangles */
 153                 double perimeter = probe_rect.w*2 + probe_rect.h*2;
 154                 double pos = 0.0;
 155
 156                 while (pos < perimeter) {
 157                         Vector vertex;
 158
 159                         if (pos < probe_rect.w) {
 160                                 /* bottom */
 161                                 vertex.x = probe_rect.x + pos;
 162                                 vertex.y = probe_rect.y + 0.0f;
 163                         } else if (pos < probe_rect.w + probe_rect.h) {
 164                                 /* right */
 165                                 vertex.x = probe_rect.x + probe_rect.w;
 166                                 vertex.y = probe_rect.y + pos - probe_rect.w;
 167                         } else if(pos < probe_rect.w*2 + probe_rect.h) {
 168                                 /* top */
 169                                 vertex.x = probe_rect.x + probe_rect.w - (pos - (probe_rect.w + probe_rect.h));
 170                                 vertex.y = probe_rect.y + probe_rect.h;
 171                         } else {
 172                                 /* left */
 173                                 vertex.x = probe_rect.x + 0.0f;
 174                                 vertex.y = probe_rect.y + probe_rect.h - (pos - (probe_rect.w*2 + probe_rect.h));
 175                         }
 176
 177                         triangle_fan.push_back(vertex);
 178                         pos += random_float();
 179                 }
 180         } else {
 181                 /* Step around a circle that contains the window */
 182                 double radius = (sqrt((double)(probe_rect.w*probe_rect.w + probe_rect.h*probe_rect.h)) / 2.0) + 5.0;
 183                 double perimeter = 2.0 * M_PI * radius;
 184                 double pos = 0.0;
 185
 186                 while (pos < perimeter) {
 187                         double theta = pos / radius;
 188
 189                         float x = probe_rect.x + 0.5 * probe_rect.w + cos(theta) * radius;
 190                         float y = probe_rect.y + 0.5 * probe_rect.h + sin(theta) * radius;
 191
 192                         triangle_fan.push_back(Vector(x, y));
 193                         pos += random_float();
 194                 }
 195         }
 196
 197         /* Complete the fan! */
 198         triangle_fan.push_back(triangle_fan.at(1));
 199         ++test_id;
 200 }
 201
 202 /* Tests a triangle fan */
 203 bool TestCase::run(void) const
 204 {
 205         glViewport(0, 0, piglit_width, piglit_height);
 206         piglit_ortho_projection(piglit_width, piglit_height, GL_FALSE);
 207
 208         /* Set render state */
 209         float colour[4];
 210         glEnable(GL_BLEND);
 211         glBlendEquation(GL_FUNC_ADD);
 212         if (rect) {
 213                 glBlendFunc(GL_ONE, GL_ONE);
 214                 colour[0] = colour[1] = colour[2] = 127.0f / 255.0f;
 215         } else {
 216                 /* Invert.
 217                  *
 218                  * When contouring a circle with very small steps, some overdraw occurs
 219                  * naturally, but it should cancel itself out, i.e., there should be an
 220                  * odd number of overdraw inside the shape, and an even number outside.
 221                  * */
 222                 glBlendFunc(GL_ONE_MINUS_DST_COLOR, GL_ZERO);
 223                 colour[0] = colour[1] = colour[2] = 1.0f;
 224         }
 225
 226         colour[3] = 1.0f;
 227         glColor4fv(colour);
 228
 229         glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
 230         glClear(GL_COLOR_BUFFER_BIT);
 231
 232         /* Draw triangle fan */
 233         glEnableClientState(GL_VERTEX_ARRAY);
 234         glVertexPointer(2, GL_FLOAT, 0, &triangle_fan.front());
 235         glDrawArrays(GL_TRIANGLE_FAN, 0, triangle_fan.size());
 236         glDisableClientState(GL_VERTEX_ARRAY);
 237
 238         /* Reset draw state */
 239         glDisable(GL_BLEND);
 240
 241         if (!piglit_probe_rect_rgb(probe_rect.x, probe_rect.y, probe_rect.w, probe_rect.y, colour)) {
 242                 printf("%d. Triangle Fan with %d triangles around (%f, %f)\n",
 243                        test_id, (int)triangle_fan.size(), mid.x, mid.y);
 244
 245                 fflush(stdout);
 246                 return false;
 247         }
 248
 249         return true;
 250 }
 251
 252 /* Render */
 253 enum piglit_result
 254 piglit_display(void)
 255 {
 256         /* Perform test */
 257         GLboolean pass = GL_TRUE;
 258
 259         TestCase test_case;
 260
 261         if (piglit_automatic) {
 262                 int fail_count = 0;
 263
 264                 printf("Running %d random tests\n", random_test_count);
 265                 fflush(stdout);
 266
 267                 for (int i = 0; i < random_test_count && !(fail_count && break_on_fail); ++i) {
 268                         test_case.generate();
 269                         if (!test_case.run())
 270                                 fail_count++;
 271                 }
 272
 273                 printf("Failed %d random tests\n", fail_count);
 274                 fflush(stdout);
 275
 276                 if (fail_count)
 277                         pass = GL_FALSE;
 278         } else {
 279                 test_case.generate();
 280                 pass = pass && test_case.run();
 281
 282                 piglit_present_results();
 283         }
 284
 285         if (!piglit_check_gl_error(GL_NO_ERROR))
 286                 piglit_report_result(PIGLIT_FAIL);
 287         return pass ? PIGLIT_PASS : PIGLIT_FAIL;
 288 }
 289
 290 /* Read command line arguments! */
 291 void
 292 piglit_init(int argc, char **argv)
 293 {
 294         uint32_t seed = 0xfacebeef ^ time(NULL);
 295
 296         for (int i = 1; i < argc; ++i) {
 297                 if (strcmp(argv[i], "-break_on_fail") == 0){
 298                         break_on_fail = true;
 299                         printf("Execution will stop on first fail\n");
 300                 } else if (strcmp(argv[i], "-rect") == 0){
 301                         rect = true;
 302                 } else if (strcmp(argv[i], "-max_size") == 0){
 303                         glGetIntegerv(GL_MAX_TEXTURE_SIZE, &piglit_width);
 304                         piglit_height = piglit_width;
 305                 } else if (strcmp(argv[i], "-clip") == 0){
 306                         clips = true;
 307                         printf("Clipped triangles are being tested\n");
 308                 } else if (i + 1 < argc) {
 309                         if (strcmp(argv[i], "-count") == 0) {
 310                                 random_test_count = strtoul(argv[++i], NULL, 0);
 311                         } else if (strcmp(argv[i], "-seed") == 0) {
 312                                 seed = strtoul(argv[++i], NULL, 0);
 313                         }
 314                 }
 315         }
 316
 317         printf("Random seed: 0x%08X\n", seed);
 318         mersenne.init(seed);
 319 }