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    /* Draw the Z image as luminance above original rendering */
  62    glWindowPos2i(0, 100);
  63    glDrawPixels(100, 100, GL_LUMINANCE, depthType, depth);
  64
  65    if (TestPacking) {
  66       glPixelStorei(GL_PACK_ROW_LENGTH, 0);
  67       glPixelStorei(GL_PACK_SKIP_PIXELS, 0);
  68       glPixelStorei(GL_UNPACK_ROW_LENGTH, 120);
  69       glPixelStorei(GL_UNPACK_SKIP_PIXELS, 5);
  70    }
  71
  72    /* draw depth image with scaling (into z buffer) */
  73    glPixelZoom(4.0, 4.0);
  74    glColor4f(1, 0, 0, 0);
  75    glWindowPos2i(100, 0);
  76    if (Invert) {
  77       glPixelTransferf(GL_DEPTH_SCALE, -1.0);
  78       glPixelTransferf(GL_DEPTH_BIAS, 1.0);
  79    }
  80    if (TestList) {
  81       list = glGenLists(1);
  82       glNewList(list, GL_COMPILE);
  83       glDrawPixels(100, 100, GL_DEPTH_COMPONENT, depthType, depth);
  84       glEndList();
  85       glCallList(list);
  86       glDeleteLists(list, 1);
  87    }
  88    else {
  89       glDrawPixels(100, 100, GL_DEPTH_COMPONENT, depthType, depth);
  90    }
  91    if (Invert) {
  92       glPixelTransferf(GL_DEPTH_SCALE, 1.0);
  93       glPixelTransferf(GL_DEPTH_BIAS, 0.0);
  94    }
  95
  96    if (TestPacking) {
  97       glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
  98       glPixelStorei(GL_UNPACK_SKIP_PIXELS, 0);
  99    }
 100
 101    glDisable(GL_DEPTH_TEST);
 102
 103    /* read back scaled depth image */
 104    glReadPixels(100, 0, 400, 400, GL_DEPTH_COMPONENT, GL_FLOAT, depth2);
 105
 106    /* debug */
 107    if (0) {
 108       int i;
 109       float *z = depth2 + 400 * 200;
 110       printf("z at y=200:\n");
 111       for (i = 0; i < 400; i++) {
 112          printf("%5.3f ", z[i]);
 113          if ((i + 1) % 12 == 0)
 114             printf("\n");
 115       }
 116    }
 117
 118    /* draw as luminance */
 119    glPixelZoom(1.0, 1.0);
 120    glWindowPos2i(100, 0);
 121    glDrawPixels(400, 400, GL_LUMINANCE, GL_FLOAT, depth2);
 122
 123    glutSwapBuffers();
 124 }
 125
 126
 127 static void Reshape(int width, int height)
 128 {
 129    WinWidth = width;
 130    WinHeight = height;
 131    glViewport(0, 0, width, height);
 132 }
 133
 134
 135 static void Key(unsigned char key, int x, int y)
 136 {
 137    (void) x;
 138    (void) y;
 139    switch (key) {
 140       case 'i':
 141          Invert = !Invert;
 142          break;
 143       case 'p':
 144          TestPacking = !TestPacking;
 145          printf("Test pixel pack/unpack: %d\n", TestPacking);
 146          break;
 147       case 'l':
 148          TestList = !TestList;
 149          printf("Test dlist: %d\n", TestList);
 150          break;
 151       case 27:
 152          exit(0);
 153          break;
 154    }
 155    glutPostRedisplay();
 156 }
 157
 158
 159 static void Init(void)
 160 {
 161    const GLfloat blue[4] = {.1, .1, 1.0, 1.0};
 162    const GLfloat gray[4] = {0.2, 0.2, 0.2, 1.0};
 163    const GLfloat white[4] = {1.0, 1.0, 1.0, 1.0};
 164    const GLfloat pos[4] = {0, 0, 10, 0};
 165
 166    printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
 167    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 168
 169    glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, blue);
 170    glLightfv(GL_LIGHT0, GL_AMBIENT, gray);
 171    glLightfv(GL_LIGHT0, GL_DIFFUSE, white);
 172    glLightfv(GL_LIGHT0, GL_POSITION, pos);
 173    glEnable(GL_LIGHTING);
 174    glEnable(GL_LIGHT0);
 175 }
 176
 177
 178 int main(int argc, char *argv[])
 179 {
 180    glutInit(&argc, argv);
 181    glutInitWindowPosition(0, 0);
 182    glutInitWindowSize(WinWidth, WinHeight);
 183    glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE);
 184    glutCreateWindow(argv[0]);
 185    glewInit();
 186    glutReshapeFunc(Reshape);
 187    glutKeyboardFunc(Key);
 188    glutDisplayFunc(Display);
 189    Init();
 190    glutMainLoop();
 191    return 0;
 192 }