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