progs/tests/zreaddraw.c

   1 /*
   2  * Test glRead/DrawPixels for GL_DEPTH_COMPONENT, with pixelzoom.
   3  *
   4  * Brian Paul
   5  * 23 August 2003
   6  */
   7
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <math.h>
  11 #include <GL/glew.h>
  12 #include <GL/glut.h>
  13
  14 static GLint WinWidth = 500, WinHeight = 500;
  15 static GLboolean Invert = GL_FALSE;
  16 static GLboolean TestPacking = GL_FALSE;
  17 static GLboolean TestList = GL_FALSE;
  18
  19
  20 static void Display(void)
  21 {
  22    GLfloat depth[100 * 100 * 2];
  23    GLfloat depth2[400 * 400]; /* *2 to test pixelstore stuff */
  24    GLuint list;
  25    GLenum depthType = GL_FLOAT;
  26
  27    glClearColor(0.5, 0.5, 0.5, 1.0);
  28    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  29
  30    glEnable(GL_DEPTH_TEST);
  31
  32    /* draw a sphere */
  33    glViewport(0, 0, 100, 100);
  34    glMatrixMode(GL_PROJECTION);
  35    glLoadIdentity();
  36    glOrtho(-1, 1, -1, 1, -1, 0);  /* clip away back half of sphere */
  37    glMatrixMode(GL_MODELVIEW);
  38    glLoadIdentity();
  39    glutSolidSphere(1.0, 20, 10);
  40
  41    if (TestPacking) {
  42       glPixelStorei(GL_PACK_ROW_LENGTH, 120);
  43       glPixelStorei(GL_PACK_SKIP_PIXELS, 5);
  44    }
  45
  46    /* read the depth image */
  47    glReadPixels(0, 0, 100, 100, GL_DEPTH_COMPONENT, depthType, depth);
  48    if (depthType == GL_FLOAT) {
  49       GLfloat min, max;
  50       int i;
  51       min = max = depth[0];
  52       for (i = 1; i < 100 * 100; i++) {
  53          if (depth[i] < min)
  54             min = depth[i];
  55          if (depth[i] > max)
  56             max = depth[i];
  57       }
  58       printf("Depth value range: [%f, %f]\n", min, max);
  59    }
  60
  61    if (TestPacking) {
  62       glPixelStorei(GL_PACK_ROW_LENGTH, 0);
  63       glPixelStorei(GL_PACK_SKIP_PIXELS, 0);
  64       glPixelStorei(GL_UNPACK_ROW_LENGTH, 120);
  65       glPixelStorei(GL_UNPACK_SKIP_PIXELS, 5);
  66    }
  67
  68    /* draw depth image with scaling (into z buffer) */
  69    glPixelZoom(4.0, 4.0);
  70    glColor4f(1, 0, 0, 0);
  71    glWindowPos2i(100, 0);
  72    if (Invert) {
  73       glPixelTransferf(GL_DEPTH_SCALE, -1.0);
  74       glPixelTransferf(GL_DEPTH_BIAS, 1.0);
  75    }
  76    if (TestList) {
  77       list = glGenLists(1);
  78       glNewList(list, GL_COMPILE);
  79       glDrawPixels(100, 100, GL_DEPTH_COMPONENT, depthType, depth);
  80       glEndList();
  81       glCallList(list);
  82       glDeleteLists(list, 1);
  83    }
  84    else {
  85       glDrawPixels(100, 100, GL_DEPTH_COMPONENT, depthType, depth);
  86    }
  87    if (Invert) {
  88       glPixelTransferf(GL_DEPTH_SCALE, 1.0);
  89       glPixelTransferf(GL_DEPTH_BIAS, 0.0);
  90    }
  91
  92    if (TestPacking) {
  93       glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
  94       glPixelStorei(GL_UNPACK_SKIP_PIXELS, 0);
  95    }
  96
  97    glDisable(GL_DEPTH_TEST);
  98
  99    /* read back scaled depth image */
 100    glReadPixels(100, 0, 400, 400, GL_DEPTH_COMPONENT, GL_FLOAT, depth2);
 101    /* draw as luminance */
 102    glPixelZoom(1.0, 1.0);
 103    glDrawPixels(400, 400, GL_LUMINANCE, GL_FLOAT, depth2);
 104
 105    glutSwapBuffers();
 106 }
 107
 108
 109 static void Reshape(int width, int height)
 110 {
 111    WinWidth = width;
 112    WinHeight = height;
 113    glViewport(0, 0, width, height);
 114 }
 115
 116
 117 static void Key(unsigned char key, int x, int y)
 118 {
 119    (void) x;
 120    (void) y;
 121    switch (key) {
 122       case 'i':
 123          Invert = !Invert;
 124          break;
 125       case 'p':
 126          TestPacking = !TestPacking;
 127          printf("Test pixel pack/unpack: %d\n", TestPacking);
 128          break;
 129       case 'l':
 130          TestList = !TestList;
 131          printf("Test dlist: %d\n", TestList);
 132          break;
 133       case 27:
 134          exit(0);
 135          break;
 136    }
 137    glutPostRedisplay();
 138 }
 139
 140
 141 static void Init(void)
 142 {
 143    const GLfloat blue[4] = {.1, .1, 1.0, 1.0};
 144    const GLfloat gray[4] = {0.2, 0.2, 0.2, 1.0};
 145    const GLfloat white[4] = {1.0, 1.0, 1.0, 1.0};
 146    const GLfloat pos[4] = {0, 0, 10, 0};
 147
 148    printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
 149    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 150
 151    glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, blue);
 152    glLightfv(GL_LIGHT0, GL_AMBIENT, gray);
 153    glLightfv(GL_LIGHT0, GL_DIFFUSE, white);
 154    glLightfv(GL_LIGHT0, GL_POSITION, pos);
 155    glEnable(GL_LIGHTING);
 156    glEnable(GL_LIGHT0);
 157 }
 158
 159
 160 int main(int argc, char *argv[])
 161 {
 162    glutInit(&argc, argv);
 163    glutInitWindowPosition(0, 0);
 164    glutInitWindowSize(WinWidth, WinHeight);
 165    glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE);
 166    glutCreateWindow(argv[0]);
 167    glewInit();
 168    glutReshapeFunc(Reshape);
 169    glutKeyboardFunc(Key);
 170    glutDisplayFunc(Display);
 171    Init();
 172    glutMainLoop();
 173    return 0;
 174 }