Brian | 370eca1 | 2008-02-28 17:42:18 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Automatic primitive rasterization precision test. |
| 3 | * |
| 4 | * Draw prims at various sub-pixel offsets and examine where the quad is |
| 5 | * actually drawn. |
| 6 | * Check if the range of offsets which paint the right pixels falls within |
| 7 | * OpenGL's specification. |
| 8 | * In case of failures, report the coordinate bias needed to fix the problem. |
| 9 | * |
| 10 | * Note that even Mesa/swrast fails some line tests. This is because some |
| 11 | * window coordinates wind up as 53.9999 instead of 54, for example. Enabling |
| 12 | * the small translation factor below fixes that. Revisit someday... |
| 13 | * |
| 14 | * Brian Paul |
| 15 | * 28 Feb 2008 |
| 16 | */ |
| 17 | |
| 18 | |
| 19 | #include <assert.h> |
| 20 | #include <stdio.h> |
| 21 | #include <stdlib.h> |
Keith Whitwell | a58065d | 2009-03-10 13:11:23 +0000 | [diff] [blame] | 22 | #include <GL/glew.h> |
Brian | 370eca1 | 2008-02-28 17:42:18 -0700 | [diff] [blame] | 23 | #include <GL/glut.h> |
| 24 | |
| 25 | |
| 26 | static int Width = 100, Height = 100; |
| 27 | static int Win; |
| 28 | static float Step = 0.125; |
| 29 | #if 0 |
| 30 | /* This tiny offset fixes errors in Mesa/Xlib */ |
| 31 | static float Xtrans = 0.5 * 0.125; |
| 32 | static float Ytrans = 0.5 * 0.125; |
| 33 | #else |
| 34 | static float Xtrans = 0.0; |
| 35 | static float Ytrans = 0.0; |
| 36 | #endif |
| 37 | |
| 38 | |
| 39 | static void |
| 40 | PointCalibrate(int xpos, int ypos) |
| 41 | { |
| 42 | GLfloat rgba[4]; |
| 43 | float x, y; |
| 44 | float xmin, ymin, xmax, ymax; |
| 45 | |
| 46 | xmin = ymin = 1000.0; |
| 47 | xmax = ymax = -1000.0; |
| 48 | |
| 49 | for (y = -1.0; y <= 1.0; y += Step) { |
| 50 | for (x = -1.0; x <= 1.0; x += Step) { |
| 51 | glClear(GL_COLOR_BUFFER_BIT); |
| 52 | glBegin(GL_POINTS); |
| 53 | glVertex2f(xpos + x, ypos + y); |
| 54 | glEnd(); |
| 55 | glReadPixels(xpos, ypos, 1, 1, GL_RGBA, GL_FLOAT, rgba); |
| 56 | if (rgba[0] == 1.0 && rgba[1] == 1.0 && rgba[2] == 1.0) { |
| 57 | /* hit */ |
| 58 | if (x < xmin) |
| 59 | xmin = x; |
| 60 | if (y < ymin) |
| 61 | ymin = y; |
| 62 | if (x > xmax) |
| 63 | xmax = x; |
| 64 | if (y > ymax) |
| 65 | ymax = y; |
| 66 | } |
| 67 | } |
| 68 | } |
| 69 | |
| 70 | printf("Point at (%2d, %2d) drawn for x in [%6.3f, %6.3f] and y in [%6.3f, %6.3f]\n", |
| 71 | xpos, ypos, |
| 72 | xpos + xmin, xpos + xmax, |
| 73 | ypos + ymin, ypos + ymax); |
| 74 | |
| 75 | if (xmax - xmin != 1.0 - Step) { |
| 76 | printf(" => Inconsistant X-axis rasterization!\n"); |
| 77 | } |
| 78 | if (ymax - ymin != 1.0 - Step) { |
| 79 | printf(" => Inconsistant Y-axis rasterization!\n"); |
| 80 | } |
| 81 | if (xmin < 0.0) { |
| 82 | printf(" => Points should be X biased by about %f\n", xmin); |
| 83 | } |
| 84 | if (ymin < 0.0) { |
| 85 | printf(" => Points should be Y biased by about %f\n", ymin); |
| 86 | } |
| 87 | if (xmax > 1.0) { |
| 88 | printf(" => Points should be X biased by about %f\n", 1.0 - xmax); |
| 89 | } |
| 90 | if (ymax > 1.0) { |
| 91 | printf(" => Points should be Y biased by about %f\n", 1.0 - ymax); |
| 92 | } |
| 93 | |
| 94 | } |
| 95 | |
| 96 | |
| 97 | /** |
| 98 | * XXX Implement VLineCalibrate() someday |
| 99 | */ |
| 100 | static void |
| 101 | HLineCalibrate(int xpos, int ypos, int len) |
| 102 | { |
| 103 | GLfloat rgba[2][4]; |
| 104 | float x, y; |
| 105 | float ymin, ymax; |
| 106 | float xmin_left, xmax_left, xmin_right, xmax_right; |
| 107 | |
| 108 | xmin_left = xmin_right = 1000.0; |
| 109 | xmax_left = xmax_right = -1000.0; |
| 110 | ymin = 1000; |
| 111 | ymax = -1000.0; |
| 112 | |
| 113 | /* |
| 114 | * First, check vertical positioning of the horizontal line |
| 115 | */ |
| 116 | for (y = -1.0; y <= 1.0; y += Step) { |
| 117 | glClear(GL_COLOR_BUFFER_BIT); |
| 118 | glBegin(GL_LINES); |
| 119 | glVertex2f(xpos, ypos + y); |
| 120 | glVertex2f(xpos + len, ypos + y); |
| 121 | glEnd(); |
| 122 | |
| 123 | glReadPixels(xpos + len / 2, ypos, 1, 1, GL_RGBA, GL_FLOAT, rgba); |
| 124 | if (rgba[0][0] == 1.0) { |
| 125 | /* hit */ |
| 126 | if (y < ymin) |
| 127 | ymin = y; |
| 128 | if (y > ymax) |
| 129 | ymax = y; |
| 130 | } |
| 131 | } |
| 132 | |
| 133 | printf("H-line at Y=%2d drawn for y in [%6.3f, %6.3f]\n", |
| 134 | ypos, |
| 135 | ypos + ymin, ypos + ymax); |
| 136 | |
| 137 | if (ymax - ymin != 1.0 - Step) { |
| 138 | printf(" => Inconsistant Y-axis rasterization!\n"); |
| 139 | } |
| 140 | |
| 141 | if (ymin > 0.5 ) { |
| 142 | printf(" => Lines should be Y biased by about %f\n", ymin - 0.5); |
| 143 | } |
| 144 | |
| 145 | if (ymax < 0.5 ) { |
| 146 | printf(" => Lines should be Y biased by about %f\n", 0.5 - ymax); |
| 147 | } |
| 148 | |
| 149 | /* |
| 150 | * Second, check endpoints (for Y at 1/2 pixel) |
| 151 | */ |
| 152 | for (x = -1.0; x <= 1.0; x += Step) { |
| 153 | glClear(GL_COLOR_BUFFER_BIT); |
| 154 | glBegin(GL_LINES); |
| 155 | glVertex2f(xpos + x, ypos + 0.5f); |
| 156 | glVertex2f(xpos + x + len, ypos + 0.5f); |
| 157 | glEnd(); |
| 158 | |
| 159 | /* left end */ |
| 160 | glReadPixels(xpos - 1, ypos, 2, 1, GL_RGBA, GL_FLOAT, rgba); |
| 161 | if (rgba[0][0] == 0.0 && rgba[1][0] == 1.0) { |
| 162 | /* hit */ |
| 163 | if (x < xmin_left) |
| 164 | xmin_left = x; |
| 165 | if (x > xmax_left) |
| 166 | xmax_left = x; |
| 167 | } |
| 168 | |
| 169 | /* right end */ |
| 170 | glReadPixels(xpos + len - 1, ypos, 2, 1, GL_RGBA, GL_FLOAT, rgba); |
| 171 | if (rgba[0][0] == 1.0 && rgba[1][0] == 0.0) { |
| 172 | /* hit */ |
| 173 | if (x < xmin_right) |
| 174 | xmin_right = x; |
| 175 | if (x > xmax_right) |
| 176 | xmax_right = x; |
| 177 | } |
| 178 | } |
| 179 | |
| 180 | printf("H-line [%d..%d) hit left end for x in [%6.3f, %6.3f] " |
| 181 | "hit right end for x in [%6.3f, %6.3f]\n", |
| 182 | xpos, xpos + len, |
| 183 | xpos + xmin_left, xpos + xmax_left, |
| 184 | xpos + len + xmin_right, xpos + len + xmax_right); |
| 185 | |
| 186 | if (xmax_left - xmin_left > 1.0 - Step) { |
| 187 | printf(" => Inconsistant left-end rasterization!\n"); |
| 188 | } |
| 189 | if (xmax_right - xmin_right > 1.0 - Step) { |
| 190 | printf(" => Inconsistant right-end rasterization!\n"); |
| 191 | } |
| 192 | |
| 193 | if (xmin_left != xmin_right || |
| 194 | xmax_left != xmax_right) { |
| 195 | printf(" => Inconsistant length!\n"); |
| 196 | } |
| 197 | |
| 198 | if (xmin_left < 0.0) { |
| 199 | printf(" => Coords should be X biased by about %f\n", xmin_left ); |
| 200 | } |
| 201 | if (xmin_right < 0.0) { |
| 202 | printf(" => Coords should be X biased by about %f\n", xmin_right ); |
| 203 | } |
| 204 | if (xmax_left >= 1.0) { |
| 205 | printf(" => Coords should be X biased by about %f\n", -xmax_right + 1.0); |
| 206 | } |
| 207 | if (xmax_right >= 1.0) { |
| 208 | printf(" => Coords should be X biased by about %f\n", -xmax_right + 1.0); |
| 209 | } |
| 210 | |
| 211 | } |
| 212 | |
| 213 | |
| 214 | static void |
| 215 | QuadCalibrate(int xpos, int ypos, int width, int height) |
| 216 | { |
| 217 | GLfloat rgba1[2][4]; |
| 218 | GLfloat rgba2[2][4]; |
| 219 | float x, y; |
| 220 | float xmin, ymin, xmax, ymax; |
| 221 | |
| 222 | xmin = ymin = 1000.0; |
| 223 | xmax = ymax = -1000.0; |
| 224 | |
| 225 | for (y = -1.0; y <= 1.0; y += Step) { |
| 226 | for (x = -1.0; x <= 1.0; x += Step) { |
| 227 | glClear(GL_COLOR_BUFFER_BIT); |
| 228 | glBegin(GL_QUADS); |
| 229 | glVertex2f(xpos + x, ypos + y); |
| 230 | glVertex2f(xpos + x + width, ypos + y); |
| 231 | glVertex2f(xpos + x + width, ypos + y + height); |
| 232 | glVertex2f(xpos + x, ypos + y + height); |
| 233 | glEnd(); |
| 234 | |
| 235 | /* horizontal measurement */ |
| 236 | glReadPixels(xpos - 1, ypos + 2, 2, 1, GL_RGBA, GL_FLOAT, rgba1); |
| 237 | glReadPixels(xpos + width - 1, ypos + 2, 2, 1, GL_RGBA, GL_FLOAT, rgba2); |
| 238 | if (rgba1[0][0] == 0.0 && rgba1[1][0] == 1.0 && |
| 239 | rgba2[0][0] == 1.0 && rgba2[1][0] == 0.0) { |
| 240 | if (x < xmin) |
| 241 | xmin = x; |
| 242 | if (x > xmax) |
| 243 | xmax = x; |
| 244 | } |
| 245 | |
| 246 | /* vertical measurement */ |
| 247 | glReadPixels(xpos + 2, ypos - 1, 1, 2, GL_RGBA, GL_FLOAT, rgba1); |
| 248 | glReadPixels(xpos + 2, ypos + height - 1, 1, 2, GL_RGBA, GL_FLOAT, rgba2); |
| 249 | if (rgba1[0][0] == 0.0 && rgba1[1][0] == 1.0 && |
| 250 | rgba2[0][0] == 1.0 && rgba2[1][0] == 0.0) { |
| 251 | if (y < ymin) |
| 252 | ymin = y; |
| 253 | if (y > ymax) |
| 254 | ymax = y; |
| 255 | } |
| 256 | } |
| 257 | } |
| 258 | |
| 259 | printf("Quad at (%2d, %2d)..(%2d, %2d) drawn" |
| 260 | " for x in [%6.3f, %6.3f] and y in [%6.3f, %6.3f]\n", |
| 261 | xpos, ypos, |
| 262 | xpos + width, ypos + height, |
| 263 | xpos + xmin, xpos + xmax, |
| 264 | ypos + ymin, ypos + ymax); |
| 265 | |
| 266 | if (xmax - xmin != 1.0 - Step) { |
| 267 | printf(" => Inconsistant X-axis rasterization/size!\n"); |
| 268 | } |
| 269 | if (ymax - ymin != 1.0 - Step) { |
| 270 | printf(" => Inconsistant Y-axis rasterization/size!\n"); |
| 271 | } |
| 272 | |
| 273 | if (xmin < -0.5) { |
| 274 | printf(" => Coords should be X biased by about %f\n", 0.5 + xmin ); |
| 275 | } |
| 276 | if (ymin < -0.5) { |
| 277 | printf(" => Coords should be Y biased by about %f\n", 0.5 + ymin); |
| 278 | } |
| 279 | if (xmax > 0.5) { |
| 280 | printf(" => Coords should be X biased by about %f\n", -xmax + 0.5); |
| 281 | } |
| 282 | if (ymax > 0.5) { |
| 283 | printf(" => Coords should be Y biased by about %f\n", -ymax + 0.5); |
| 284 | } |
| 285 | } |
| 286 | |
| 287 | |
| 288 | /** |
| 289 | * Misc/disabled code for debugging. |
| 290 | */ |
| 291 | static void |
| 292 | DebugTest(void) |
| 293 | { |
| 294 | glClear(GL_COLOR_BUFFER_BIT); |
| 295 | glEnable(GL_BLEND); |
| 296 | glBlendFunc(GL_ONE, GL_ONE); |
| 297 | |
| 298 | glColor3f(.5, .5, .5); |
| 299 | |
| 300 | glBegin(GL_LINES); |
| 301 | glVertex2f(30, 35.5); |
| 302 | glVertex2f(54, 35.5); |
| 303 | glVertex2f(54, 35.5); |
| 304 | glVertex2f(66, 35.5); |
| 305 | glEnd(); |
| 306 | |
| 307 | glDisable(GL_BLEND); |
| 308 | glColor3f(1,1,1); |
| 309 | } |
| 310 | |
| 311 | |
| 312 | static void |
| 313 | Draw(void) |
| 314 | { |
| 315 | glClear(GL_COLOR_BUFFER_BIT); |
| 316 | |
| 317 | glPushMatrix(); |
| 318 | glTranslatef(Xtrans, Ytrans, 0); |
| 319 | |
| 320 | PointCalibrate(1, 1); |
| 321 | PointCalibrate(50, 50); |
| 322 | PointCalibrate(28, 17); |
| 323 | PointCalibrate(17, 18); |
| 324 | printf("\n"); |
| 325 | |
| 326 | HLineCalibrate(5, 10, 10); |
| 327 | HLineCalibrate(25, 22, 12); |
| 328 | HLineCalibrate(54, 33, 12); |
| 329 | HLineCalibrate(54+12, 33, 12); |
| 330 | printf("\n"); |
| 331 | |
| 332 | QuadCalibrate(2, 2, 10, 10); |
| 333 | QuadCalibrate(50, 50, 10, 10); |
| 334 | QuadCalibrate(28, 17, 12, 12); |
| 335 | QuadCalibrate(17, 28, 12, 12); |
| 336 | |
| 337 | (void) DebugTest; |
| 338 | |
| 339 | glPopMatrix(); |
| 340 | |
| 341 | glutSwapBuffers(); |
| 342 | } |
| 343 | |
| 344 | |
| 345 | static void |
| 346 | Reshape(int width, int height) |
| 347 | { |
| 348 | Width = width; |
| 349 | Height = height; |
| 350 | glViewport(0, 0, width, height); |
| 351 | glMatrixMode(GL_PROJECTION); |
| 352 | glLoadIdentity(); |
| 353 | glOrtho(0, width, 0, height, -1, 1); |
| 354 | glMatrixMode(GL_MODELVIEW); |
| 355 | glLoadIdentity(); |
| 356 | } |
| 357 | |
| 358 | |
| 359 | static void |
| 360 | Key(unsigned char key, int x, int y) |
| 361 | { |
| 362 | (void) x; |
| 363 | (void) y; |
| 364 | switch (key) { |
| 365 | case 27: |
| 366 | glutDestroyWindow(Win); |
| 367 | exit(0); |
| 368 | break; |
| 369 | } |
| 370 | glutPostRedisplay(); |
| 371 | } |
| 372 | |
| 373 | |
| 374 | static void |
| 375 | Init(void) |
| 376 | { |
| 377 | printf("Measurement/callibration for basic prim rasterization...\n"); |
| 378 | printf("GL_RENDERER: %s\n", (char*) glGetString(GL_RENDERER)); |
| 379 | } |
| 380 | |
| 381 | |
| 382 | int |
| 383 | main(int argc, char *argv[]) |
| 384 | { |
| 385 | glutInit(&argc, argv); |
| 386 | glutInitWindowPosition(0, 0); |
| 387 | glutInitWindowSize(Width, Height); |
| 388 | glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE); |
| 389 | Win = glutCreateWindow(argv[0]); |
Keith Whitwell | a58065d | 2009-03-10 13:11:23 +0000 | [diff] [blame] | 390 | glewInit(); |
Brian | 370eca1 | 2008-02-28 17:42:18 -0700 | [diff] [blame] | 391 | glutReshapeFunc(Reshape); |
| 392 | glutKeyboardFunc(Key); |
| 393 | glutDisplayFunc(Draw); |
| 394 | Init(); |
| 395 | glutMainLoop(); |
| 396 | return 0; |
| 397 | } |