progs/tests/zcomp.c

   1 /**
   2  * Test Z compositing with glDrawPixels(GL_DEPTH_COMPONENT) and stencil test.
   3  */
   4
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <math.h>
   8 #include <GL/glew.h>
   9 #include <GL/glut.h>
  10 #include "../util/showbuffer.c"
  11
  12
  13 static int Win;
  14 static GLfloat Xrot = 0, Yrot = 0, Zpos = 6;
  15 static GLboolean Anim = GL_FALSE;
  16
  17 static int Width = 400, Height = 200;
  18 static GLfloat *Zimg;
  19 static GLubyte *Cimg;
  20 static GLboolean showZ = 0;
  21
  22
  23 static void
  24 Idle(void)
  25 {
  26    Xrot += 3.0;
  27    Yrot += 4.0;
  28    glutPostRedisplay();
  29 }
  30
  31
  32 /**
  33  * Draw first object, save color+Z images
  34  */
  35 static void
  36 DrawFirst(void)
  37 {
  38    static const GLfloat red[4] = { 1.0, 0.0, 0.0, 0.0 };
  39
  40    glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, red);
  41
  42    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  43
  44    glPushMatrix();
  45    glTranslatef(-1, 0, 0);
  46    glRotatef(45 + Xrot, 1, 0, 0);
  47
  48    glutSolidTorus(0.75, 2.0, 10, 20);
  49
  50    glPopMatrix();
  51
  52    glReadPixels(0, 0, Width, Height, GL_DEPTH_COMPONENT, GL_FLOAT, Zimg);
  53    glReadPixels(0, 0, Width, Height, GL_RGBA, GL_UNSIGNED_BYTE, Cimg);
  54 }
  55
  56
  57 /**
  58  * Draw second object.
  59  */
  60 static void
  61 DrawSecond(void)
  62 {
  63    static const GLfloat blue[4] = { 0.0, 0.0, 1.0, 0.0 };
  64
  65    glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, blue);
  66
  67    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
  68
  69    glPushMatrix();
  70    glTranslatef(+1, 0, 0);
  71    glRotatef(-45 + Xrot, 1, 0, 0);
  72
  73    glutSolidTorus(0.75, 2.0, 10, 20);
  74
  75    glPopMatrix();
  76 }
  77
  78
  79 /**
  80  * Composite first/saved image over second rendering.
  81  */
  82 static void
  83 Composite(void)
  84 {
  85    glWindowPos2i(0, 0);
  86
  87    /* Draw Z values, set stencil where Z test passes */
  88    glEnable(GL_STENCIL_TEST);
  89    glStencilFunc(GL_ALWAYS, 1, ~0);
  90    glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
  91    glColorMask(0,0,0,0);
  92    glDrawPixels(Width, Height, GL_DEPTH_COMPONENT, GL_FLOAT, Zimg);
  93    glColorMask(1,1,1,1);
  94
  95    /* Draw color where stencil==1 */
  96    glStencilFunc(GL_EQUAL, 1, ~0);
  97    glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
  98    glDisable(GL_DEPTH_TEST);
  99    glDrawPixels(Width, Height, GL_RGBA, GL_UNSIGNED_BYTE, Cimg);
 100    glEnable(GL_DEPTH_TEST);
 101
 102    glDisable(GL_STENCIL_TEST);
 103 }
 104
 105
 106 static void
 107 Draw(void)
 108 {
 109    DrawFirst();
 110    DrawSecond();
 111    Composite();
 112    glutSwapBuffers();
 113 }
 114
 115
 116 static void
 117 Reshape(int width, int height)
 118 {
 119    GLfloat ar = (float) width / height;
 120    glViewport(0, 0, width, height);
 121    glMatrixMode(GL_PROJECTION);
 122    glLoadIdentity();
 123    glFrustum(-ar, ar, -1.0, 1.0, 5.0, 30.0);
 124    glMatrixMode(GL_MODELVIEW);
 125    glLoadIdentity();
 126    glTranslatef(0.0, 0.0, -15.0);
 127
 128    Width = width;
 129    Height = height;
 130
 131    if (Zimg)
 132       free(Zimg);
 133    if (Cimg)
 134       free(Cimg);
 135    Zimg = (float *) malloc(width * height * 4);
 136    Cimg = (GLubyte *) malloc(width * height * 4);
 137 }
 138
 139
 140 static void
 141 Key(unsigned char key, int x, int y)
 142 {
 143    const GLfloat step = 1.0;
 144    (void) x;
 145    (void) y;
 146    switch (key) {
 147       case 'a':
 148          Anim = !Anim;
 149          if (Anim)
 150             glutIdleFunc(Idle);
 151          else
 152             glutIdleFunc(NULL);
 153          break;
 154       case 'd':
 155          showZ = !showZ;
 156          break;
 157       case 'z':
 158          Zpos -= step;
 159          break;
 160       case 'Z':
 161          Zpos += step;
 162          break;
 163       case 27:
 164          glutDestroyWindow(Win);
 165          exit(0);
 166          break;
 167    }
 168    glutPostRedisplay();
 169 }
 170
 171
 172 static void
 173 SpecialKey(int key, int x, int y)
 174 {
 175    const GLfloat step = 3.0;
 176    (void) x;
 177    (void) y;
 178    switch (key) {
 179       case GLUT_KEY_UP:
 180          Xrot -= step;
 181          break;
 182       case GLUT_KEY_DOWN:
 183          Xrot += step;
 184          break;
 185       case GLUT_KEY_LEFT:
 186          Yrot -= step;
 187          break;
 188       case GLUT_KEY_RIGHT:
 189          Yrot += step;
 190          break;
 191    }
 192    glutPostRedisplay();
 193 }
 194
 195
 196 static void
 197 Init(void)
 198 {
 199    /* setup lighting, etc */
 200    glEnable(GL_DEPTH_TEST);
 201    glEnable(GL_LIGHTING);
 202    glEnable(GL_LIGHT0);
 203 }
 204
 205
 206 int
 207 main(int argc, char *argv[])
 208 {
 209    glutInit(&argc, argv);
 210    glutInitWindowPosition(0, 0);
 211    glutInitWindowSize(Width, Height);
 212    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH | GLUT_STENCIL);
 213    Win = glutCreateWindow(argv[0]);
 214    glewInit();
 215    glutReshapeFunc(Reshape);
 216    glutKeyboardFunc(Key);
 217    glutSpecialFunc(SpecialKey);
 218    glutDisplayFunc(Draw);
 219    if (Anim)
 220       glutIdleFunc(Idle);
 221    Init();
 222    glutMainLoop();
 223    return 0;
 224 }