18. Depth Testing

• Culling the back-facing triangles does not solve the problem with front-facing triangles positioned in front of one another.

• Depth testing solves this problem and removes hidden surfaces

• Each pixel has a depth (z-value)

• Higher values mean closer to the camera

• Pixel depth values are stored in the depth buffer

  
      glutInitDisplayMode( GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH );
      glEnable(GL_DEPTH_TEST);// Make sure the depth buffer is on.