四面体由4个三角形组成
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear Screen And Depth Buffer
 glLoadIdentity();         // Reset The Current Modelview Matrix
 glTranslatef(-1.5f,0.0f,-6.0f);      // Move Left 1.5 Units And Into The Screen 6.0
 glRotatef(rtri,0.0f,1.0f,0.0f);      // Rotate The Triangle On The Y axis ( NEW )
 glBegin(GL_TRIANGLES);        // Start Drawing A Triangle
  glColor3f(1.0f,0.0f,0.0f);      // Red
  glVertex3f( 0.0f, 1.0f, 0.0f);     // Top Of Triangle (Front)
  glColor3f(0.0f,1.0f,0.0f);      // Green
  glVertex3f(-1.0f,-1.0f, 1.0f);     // Left Of Triangle (Front)
  glColor3f(0.0f,0.0f,1.0f);      // Blue
  glVertex3f( 1.0f,-1.0f, 1.0f);     // Right Of Triangle (Front)
  glColor3f(1.0f,0.0f,0.0f);      // Red
  glVertex3f( 0.0f, 1.0f, 0.0f);     // Top Of Triangle (Right)
  glColor3f(0.0f,0.0f,1.0f);      // Blue
  glVertex3f( 1.0f,-1.0f, 1.0f);     // Left Of Triangle (Right)
  glColor3f(0.0f,1.0f,0.0f);      // Green
  glVertex3f( 1.0f,-1.0f, -1.0f);     // Right Of Triangle (Right)
  glColor3f(1.0f,0.0f,0.0f);      // Red
  glVertex3f( 0.0f, 1.0f, 0.0f);     // Top Of Triangle (Back)
  glColor3f(0.0f,1.0f,0.0f);      // Green
  glVertex3f( 1.0f,-1.0f, -1.0f);     // Left Of Triangle (Back)
  glColor3f(0.0f,0.0f,1.0f);      // Blue
  glVertex3f(-1.0f,-1.0f, -1.0f);     // Right Of Triangle (Back)
  glColor3f(1.0f,0.0f,0.0f);      // Red
  glVertex3f( 0.0f, 1.0f, 0.0f);     // Top Of Triangle (Left)
  glColor3f(0.0f,0.0f,1.0f);      // Blue
  glVertex3f(-1.0f,-1.0f,-1.0f);     // Left Of Triangle (Left)
  glColor3f(0.0f,1.0f,0.0f);      // Green
  glVertex3f(-1.0f,-1.0f, 1.0f);     // Right Of Triangle (Left)
 glEnd();