src/tests/quads.c

   1 /**
   2  * Draw colored quads.
   3  */
   4
   5
   6 #include <stdio.h>
   7 #include <stdlib.h>
   8 #include <math.h>
   9 #include <GL/glew.h>
  10 #include "glut_wrap.h"
  11
  12 #define NUM_QUADS 20
  13
  14
  15 static int Win;
  16 static GLfloat Xrot = 40, Yrot = 0, Zrot = 0;
  17 static GLboolean Anim = GL_TRUE;
  18 static GLuint Vbuffer = 0;
  19
  20 #if 1
  21 #else
  22 static GLfloat buf[NUM_QUADS * 6 * 4];
  23 #endif
  24
  25 static GLboolean doSwapBuffers = GL_TRUE;
  26
  27 static GLint Frames = 0, T0 = 0;
  28
  29
  30 static void
  31 Idle(void)
  32 {
  33    Xrot += 3.0;
  34    Yrot += 4.0;
  35    Zrot += 2.0;
  36    glutPostRedisplay();
  37 }
  38
  39
  40 static void
  41 Draw(void)
  42 {
  43    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  44
  45    glPushMatrix();
  46    glRotatef(Xrot, 1, 0, 0);
  47    glRotatef(Yrot, 0, 1, 0);
  48    glRotatef(Zrot, 0, 0, 1);
  49
  50    glDrawArrays(GL_QUADS, 0, NUM_QUADS*4);
  51
  52    glPopMatrix();
  53
  54    if (doSwapBuffers)
  55       glutSwapBuffers();
  56    /*
  57    else
  58       glFinish();
  59    */
  60
  61    {
  62       GLint t = glutGet(GLUT_ELAPSED_TIME);
  63       Frames++;
  64       if (t - T0 >= 5000) {
  65          GLfloat seconds = (t - T0) / 1000.0;
  66          GLfloat fps = Frames / seconds;
  67          printf("%d frames in %6.3f seconds = %6.3f FPS\n",
  68                 Frames, seconds, fps);
  69          T0 = t;
  70          Frames = 0;
  71       }
  72    }
  73 }
  74
  75
  76 static void
  77 Reshape(int width, int height)
  78 {
  79    glViewport(0, 0, width, height);
  80    glMatrixMode(GL_PROJECTION);
  81    glLoadIdentity();
  82    glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
  83    glMatrixMode(GL_MODELVIEW);
  84    glLoadIdentity();
  85    glTranslatef(0.0, 0.0, -8.0);
  86 }
  87
  88
  89 static void
  90 Key(unsigned char key, int x, int y)
  91 {
  92    const GLfloat step = 3.0;
  93    (void) x;
  94    (void) y;
  95    switch (key) {
  96       case 's':
  97          doSwapBuffers = !doSwapBuffers;
  98          break;
  99       case 'a':
 100          Anim = !Anim;
 101          if (Anim)
 102             glutIdleFunc(Idle);
 103          else
 104             glutIdleFunc(NULL);
 105          break;
 106       case 'z':
 107          Zrot -= step;
 108          break;
 109       case 'Z':
 110          Zrot += step;
 111          break;
 112       case 27:
 113          glutDestroyWindow(Win);
 114          exit(0);
 115          break;
 116    }
 117    glutPostRedisplay();
 118 }
 119
 120
 121 static void
 122 SpecialKey(int key, int x, int y)
 123 {
 124    const GLfloat step = 3.0;
 125    (void) x;
 126    (void) y;
 127    switch (key) {
 128       case GLUT_KEY_UP:
 129          Xrot -= step;
 130          break;
 131       case GLUT_KEY_DOWN:
 132          Xrot += step;
 133          break;
 134       case GLUT_KEY_LEFT:
 135          Yrot -= step;
 136          break;
 137       case GLUT_KEY_RIGHT:
 138          Yrot += step;
 139          break;
 140    }
 141    glutPostRedisplay();
 142 }
 143
 144
 145 static void
 146 quad(float x, float y, float z, float *v)
 147 {
 148    int k = 0;
 149
 150    /* color */
 151    v[k++] = x * 0.5 + 0.5;
 152    v[k++] = y * 0.5 + 0.5;
 153    v[k++] = z * 0.5 + 0.5;
 154    /* vert */
 155    v[k++] = x;
 156    v[k++] = y;
 157    v[k++] = z;
 158
 159    /* color */
 160    v[k++] = -x * 0.5 + 0.5;
 161    v[k++] = -y * 0.5 + 0.5;
 162    v[k++] = z * 0.5 + 0.5;
 163    /* vert */
 164    v[k++] = -x;
 165    v[k++] = -y;
 166    v[k++] = z;
 167
 168    /* color */
 169    v[k++] = -x * 0.5 + 0.5;
 170    v[k++] = -y * 0.5 + 0.5;
 171    v[k++] = -z * 0.5 + 0.5;
 172    /* vert */
 173    v[k++] = -x;
 174    v[k++] = -y;
 175    v[k++] = -z;
 176
 177    /* color */
 178    v[k++] = x * 0.5 + 0.5;
 179    v[k++] = y * 0.5 + 0.5;
 180    v[k++] = -z * 0.5 + 0.5;
 181    /* vert */
 182    v[k++] = x;
 183    v[k++] = y;
 184    v[k++] = -z;
 185 }
 186
 187 static void
 188 gen_quads(GLfloat *buf)
 189 {
 190    float *v = buf;
 191    float r = 1.0;
 192    int i;
 193
 194    for (i = 0; i < NUM_QUADS; i++) {
 195       float angle = i / (float) NUM_QUADS * M_PI;
 196       float x = r * cos(angle);
 197       float y = r * sin(angle);
 198       float z = 1.10;
 199       quad(x, y, z, v);
 200       v += 24;
 201    }
 202
 203    if (0) {
 204       float *p = buf;
 205       for (i = 0; i < NUM_QUADS * 4 * 2; i++) {
 206          printf("%d: %f %f %f\n", i, p[0], p[1], p[2]);
 207          p += 3;
 208       }
 209    }
 210 }
 211
 212
 213 static void
 214 Init(void)
 215 {
 216    int bytes = NUM_QUADS * 4 * 2 * 3 * sizeof(float);
 217    GLfloat *f;
 218
 219 #if 1
 220    glGenBuffers(1, &Vbuffer);
 221    glBindBuffer(GL_ARRAY_BUFFER, Vbuffer);
 222    glBufferData(GL_ARRAY_BUFFER_ARB, bytes, NULL, GL_STATIC_DRAW_ARB);
 223    f = (float *) glMapBuffer(GL_ARRAY_BUFFER_ARB, GL_WRITE_ONLY_ARB);
 224    gen_quads(f);
 225    glUnmapBuffer(GL_ARRAY_BUFFER_ARB);
 226    glColorPointer(3, GL_FLOAT, 6*sizeof(float), (void *) 0);
 227    glVertexPointer(3, GL_FLOAT, 6*sizeof(float), (void *) 12);
 228 #else
 229    f = buf;
 230    gen_quads(f);
 231    glColorPointer(3, GL_FLOAT, 6*sizeof(float), buf);
 232    glVertexPointer(3, GL_FLOAT, 6*sizeof(float), buf + 3);
 233 #endif
 234
 235    glEnableClientState(GL_COLOR_ARRAY);
 236    glEnableClientState(GL_VERTEX_ARRAY);
 237
 238    glEnable(GL_DEPTH_TEST);
 239
 240    glClearColor(0.5, 0.5, 0.5, 0.0);
 241 }
 242
 243
 244 int
 245 main(int argc, char *argv[])
 246 {
 247    glutInit(&argc, argv);
 248    glutInitWindowPosition(0, 0);
 249    glutInitWindowSize(600, 600);
 250    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
 251    Win = glutCreateWindow(argv[0]);
 252    glewInit();
 253    glutReshapeFunc(Reshape);
 254    glutKeyboardFunc(Key);
 255    glutSpecialFunc(SpecialKey);
 256    glutDisplayFunc(Draw);
 257    if (Anim)
 258       glutIdleFunc(Idle);
 259    Init();
 260    glutMainLoop();
 261    return 0;
 262 }