progs/tests/calibrate_rast.c

   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>
  22 #include <GL/glew.h>
  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]);
 390    glewInit();
 391    glutReshapeFunc(Reshape);
 392    glutKeyboardFunc(Key);
 393    glutDisplayFunc(Draw);
 394    Init();
 395    glutMainLoop();
 396    return 0;
 397 }