progs/tests/cylwrap.c

   1 /*
   2  * Test cylindrical texcoord wrapping
   3  */
   4
   5
   6 #include <stdio.h>
   7 #include <stdlib.h>
   8 #include <math.h>
   9 #include <GL/glut.h>
  10
  11 static int Win;
  12 static int WinWidth = 600, WinHeight = 400;
  13 static GLfloat Xrot = 0, Yrot = 0;
  14 static GLboolean CylWrap = GL_TRUE;
  15 static GLboolean Lines = GL_FALSE;
  16
  17
  18
  19 static void
  20 PrintString(const char *s)
  21 {
  22    while (*s) {
  23       glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
  24       s++;
  25    }
  26 }
  27
  28
  29 static void
  30 DrawSample(GLboolean wrap)
  31 {
  32    float p;
  33
  34    glEnable(GL_TEXTURE_2D);
  35
  36    if (Lines) {
  37       /* texured lines */
  38       float t;
  39       for (t = 0; t <= 1.0; t += 0.125) {
  40          float y = -1.0 + 2.0 * t;
  41          glBegin(GL_LINE_STRIP);
  42          for (p = 0.0; p <= 1.001; p += 0.05) {
  43             float x = -2.0 + p * 4.0;
  44             float s = p + 0.5;
  45             if (wrap && s > 1.0)
  46                s -= 1.0;
  47             glTexCoord2f(s, t);  glVertex2f(x, y);
  48          }
  49          glEnd();
  50       }
  51    }
  52    else {
  53       /* texured quads */
  54       glBegin(GL_QUAD_STRIP);
  55       for (p = 0.0; p <= 1.001; p += 0.1) {
  56          float x = -2.0 + p * 4.0;
  57          float s = p + 0.5;
  58          if (wrap && s > 1.0)
  59             s -= 1.0;
  60          glTexCoord2f(s, 0);  glVertex2f(x, -1);
  61          glTexCoord2f(s, 1);  glVertex2f(x, +1);
  62       }
  63       glEnd();
  64    }
  65
  66    glDisable(GL_TEXTURE_2D);
  67
  68    /* hash marks */
  69    glColor3f(0,0,0);
  70    glBegin(GL_LINES);
  71    for (p = 0.0; p <= 1.001; p += 0.1) {
  72       float x = -2.0 + p * 4.0;
  73       glVertex2f(x, -1.1);
  74       glVertex2f(x, -0.8);
  75    }
  76    glEnd();
  77
  78    /* labels */
  79    glColor3f(1,1,1);
  80    for (p = 0.0; p <= 1.001; p += 0.1) {
  81       char str[100];
  82       float x = -2.0 + p * 4.0;
  83       float s = p + 0.5;
  84
  85       if (wrap && s > 1.0)
  86          s -= 1.0;
  87
  88       sprintf(str, "%3.1f", s);
  89       glRasterPos2f(x, -1.2);
  90       glBitmap(0, 0, 0, 0, -11, 0, NULL);
  91       PrintString(str);
  92       if (p == 0.0) {
  93          glBitmap(0, 0, 0, 0, -55, 0, NULL);
  94          PrintString("s =");
  95       }
  96    }
  97 }
  98
  99
 100 static void
 101 Draw(void)
 102 {
 103    glClear(GL_COLOR_BUFFER_BIT);
 104
 105    glPushMatrix();
 106       glRotatef(Xrot, 1, 0, 0);
 107       glRotatef(Yrot, 0, 1, 0);
 108
 109       glPushMatrix();
 110          glTranslatef(0, +1.2, 0);
 111          DrawSample(GL_FALSE);
 112       glPopMatrix();
 113
 114       /* set Mesa back-door state for testing cylindrical wrap mode */
 115       if (CylWrap)
 116          glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_PRIORITY, 0.125);
 117
 118       glPushMatrix();
 119          glTranslatef(0, -1.2, 0);
 120          DrawSample(GL_TRUE);
 121       glPopMatrix();
 122
 123       glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_PRIORITY, 1.0);
 124
 125    glPopMatrix();
 126
 127    glutSwapBuffers();
 128 }
 129
 130
 131 static void
 132 Reshape(int width, int height)
 133 {
 134    WinWidth = width;
 135    WinHeight = height;
 136    glViewport(0, 0, width, height);
 137    glMatrixMode(GL_PROJECTION);
 138    glLoadIdentity();
 139    glFrustum(-1.0, 1.0, -1.0, 1.0, 3.0, 25.0);
 140    glMatrixMode(GL_MODELVIEW);
 141    glLoadIdentity();
 142    glTranslatef(0.0, 0.0, -10.0);
 143 }
 144
 145
 146 static void
 147 Key(unsigned char key, int x, int y)
 148 {
 149    (void) x;
 150    (void) y;
 151    switch (key) {
 152    case 'c':
 153    case 'C':
 154       CylWrap = !CylWrap;
 155       if (CylWrap)
 156          printf("Cylindrical wrap on.\n");
 157       else
 158          printf("Cylindrical wrap off.\n");
 159       break;
 160    case 'l':
 161    case 'L':
 162       Lines = !Lines;
 163       break;
 164    case 27:
 165       glutDestroyWindow(Win);
 166       exit(0);
 167       break;
 168    }
 169    glutPostRedisplay();
 170 }
 171
 172
 173 static void
 174 SpecialKey(int key, int x, int y)
 175 {
 176    const GLfloat step = 3.0;
 177    (void) x;
 178    (void) y;
 179    switch (key) {
 180    case GLUT_KEY_UP:
 181       Xrot -= step;
 182       break;
 183    case GLUT_KEY_DOWN:
 184       Xrot += step;
 185       break;
 186    case GLUT_KEY_LEFT:
 187       Yrot -= step;
 188       break;
 189    case GLUT_KEY_RIGHT:
 190       Yrot += step;
 191       break;
 192    }
 193    glutPostRedisplay();
 194 }
 195
 196
 197 static void
 198 MakeSineWaveTexture(void)
 199 {
 200    GLubyte tex[128][512][4];
 201    int i, j;
 202
 203    for (j = 0; j < 128; j++) {
 204       for (i = 0; i < 512; i++) {
 205          float x = i / 511.0 * 2.0 * M_PI + M_PI * 0.5;
 206          float y0 = sin(x) * 0.5 + 0.5;
 207          int jy0 = y0 * 128;
 208          float y1 = sin(x + M_PI) * 0.5 + 0.5;
 209          int jy1 = y1 * 128;
 210          if (j < jy0)
 211             tex[j][i][0] = 0xff;
 212          else
 213             tex[j][i][0] = 0;
 214          if (j < jy1)
 215             tex[j][i][1] = 0xff;
 216          else
 217             tex[j][i][1] = 0;
 218          tex[j][i][2] = 0;
 219          tex[j][i][3] = 0xff;
 220       }
 221    }
 222
 223    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 512, 128, 0,
 224                 GL_RGBA, GL_UNSIGNED_BYTE, tex);
 225    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 226    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 227    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
 228 }
 229
 230
 231 static void
 232 Init(void)
 233 {
 234    glBindTexture(GL_TEXTURE_2D, 5);
 235    MakeSineWaveTexture();
 236
 237    glClearColor(0.5, 0.5, 0.5, 0.0);
 238    glPointSize(3.0);
 239
 240    printf("Press 'c' to toggle cylindrical wrap mode.\n");
 241    printf("Press 'l' to toggle line / quad drawing.\n");
 242 }
 243
 244
 245 int
 246 main(int argc, char *argv[])
 247 {
 248    glutInit(&argc, argv);
 249    glutInitWindowSize(WinWidth, WinHeight);
 250    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
 251    Win = glutCreateWindow(argv[0]);
 252    glutReshapeFunc(Reshape);
 253    glutSpecialFunc(SpecialKey);
 254    glutKeyboardFunc(Key);
 255    glutDisplayFunc(Draw);
 256    Init();
 257    glutMainLoop();
 258    return 0;
 259 }