class wcPt3D {
      public:
         GLfloat x, y, z;
   };

   \* Procedure for generating a matrix for rotation about an 
    * an axis defined with points p1 and p2.
    */
   void rotate3D (wcPt3D p1, wcPt3D p2, GLfloat thetaDegrees)
   {
      /*  Set up components for rotation-axis vector.  */
      float vx = (p2.x - p1.x);
      float vy = (p2.y - p1.y);
      float vz = (p2.z - p1.z);

      /* Specfy translate-rotate-translate sequence in reverse order: */
      glTranslatef (p1.x, p1.y, p1.z); // Move p1 back to original position.
      /*  Rotate about axis through origin:  */
      glRotatef (thetaDegrees, vx, vy, vz); 
      glTranslatef (-p1.x, -p1.y, -p1.z);  // Translate p1 to origin.
   }

   /*  Procedure for generating a matrix for a scaling 
    *  transformation with respect to an arbitrary fixed point. 
    */
   void scale3D (GLfloat sx, GLfloat sy, GLfloat sz, wcPt3D fixedPt)
   {
      /* Specfy translate-scale-translate sequence in reverse order: */
      /* (3) Translate fixed point back to original position: */
      glTranslatef (fixedPt.x, fixedPt.y, fixedPt.z);
      glScalef (sx, sy, sz);      // (2) Scale with respect to origin.
      /* (1) Translate fixed point to coordinate origin: */
      glTranslatef (-fixedPt.x, -fixedPt.y, -fixedPt.z);
   }

   void displayFcn (void)
   {
      /*  Input object description.  */
      /*  Set up 3D viewing-transformation routines. */
      /*  Display object.  */

      glMatrixMode (GL_MODELVIEW);

      /* Input translation parameters tx, ty, tz. */
      /* Input the defining points, p1 and p2, for the rotation axis. */
      /* Input rotation angle in degrees. */
      /* Input scaling parameters: sx, sy, sz, and fixedPt. */

      /*  Invoke geometric transformations in reverse order:  */
      glTranslatef (tx, ty, tz);     // Final transformation: Translate.
      scale3D (sx, sy, sz, fixedPt);    // Second transformation: Scale.
      rotate3D (p1, p2, thetaDegrees);  // First transformation: Rotate.

      /*  Call routines for displaying transformed objects.  */
   }