import java.applet.*;
    import java.awt.*;
    import java.awt.event.*;
    import java.lang.Math;

    class Point3D {
       public int x, y, z;
       public Point3D( int X, int Y, int Z ) {
          x = X;  y = Y;  z = Z;
       }
    }

    class Edge {
       public int a, b;
       public Edge( int A, int B ) {
          a = A;  b = B;
       }
    }

    public class WireframeViewer extends Applet
       implements MouseListener, MouseMotionListener {

       int width, height;
       int mx, my;  // the most recently recorded mouse coordinates

       Image backbuffer;
       Graphics backg;

       int azimuth = 35, elevation = 30;

       Point3D[] vertices;
       Edge[] edges;

       public void init() {
          width = getSize().width;
          height = getSize().height;

          vertices = new Point3D[ 8 ];
          vertices[0] = new Point3D( -1, -1, -1 );
          vertices[1] = new Point3D( -1, -1,  1 );
          vertices[2] = new Point3D( -1,  1, -1 );
          vertices[3] = new Point3D( -1,  1,  1 );
          vertices[4] = new Point3D(  1, -1, -1 );
          vertices[5] = new Point3D(  1, -1,  1 );
          vertices[6] = new Point3D(  1,  1, -1 );
          vertices[7] = new Point3D(  1,  1,  1 );

          edges = new Edge[ 12 ];
          edges[ 0] = new Edge( 0, 1 );
          edges[ 1] = new Edge( 0, 2 );
          edges[ 2] = new Edge( 0, 4 );
          edges[ 3] = new Edge( 1, 3 );
          edges[ 4] = new Edge( 1, 5 );
          edges[ 5] = new Edge( 2, 3 );
          edges[ 6] = new Edge( 2, 6 );
          edges[ 7] = new Edge( 3, 7 );
          edges[ 8] = new Edge( 4, 5 );
          edges[ 9] = new Edge( 4, 6 );
          edges[10] = new Edge( 5, 7 );
          edges[11] = new Edge( 6, 7 );

          backbuffer = createImage( width, height );
          backg = backbuffer.getGraphics();
          drawWireframe( backg );

          addMouseListener( this );
          addMouseMotionListener( this );
       }

       void drawWireframe( Graphics g ) {

          // compute coefficients for the projection
          double theta = Math.PI * azimuth / 180.0;
          double phi = Math.PI * elevation / 180.0;
          float cosT = (float)Math.cos( theta ), sinT = (float)Math.sin( theta );
          float cosP = (float)Math.cos( phi ), sinP = (float)Math.sin( phi );
          float cosTcosP = cosT*cosP, cosTsinP = cosT*sinP,
                 sinTcosP = sinT*cosP, sinTsinP = sinT*sinP;

          // project vertices onto the 2D viewport
          Point[] points;
          points = new Point[ vertices.length ];
          int j;
          int scaleFactor = width/4;
          float near = 3;  // distance from eye to near plane
          float nearToObj = 1.5f;  // distance from near plane to center of object
          for ( j = 0; j < vertices.length; ++j ) {
             int x0 = vertices[j].x;
             int y0 = vertices[j].y;
             int z0 = vertices[j].z;

             // compute an orthographic projection
             float x1 = cosT*x0 + sinT*z0;
             float y1 = -sinTsinP*x0 + cosP*y0 + cosTsinP*z0;

             // now adjust things to get a perspective projection
             float z1 = cosTcosP*z0 - sinTcosP*x0 - sinP*y0;
             x1 = x1*near/(z1+near+nearToObj);
             y1 = y1*near/(z1+near+nearToObj);

             // the 0.5 is to round off when converting to int
             points[j] = new Point(
                (int)(width/2 + scaleFactor*x1 + 0.5),
                (int)(height/2 - scaleFactor*y1 + 0.5)
             );
          }

          // draw the wireframe
          g.setColor( Color.black );
          g.fillRect( 0, 0, width, height );
          g.setColor( Color.white );
          for ( j = 0; j < edges.length; ++j ) {
             g.drawLine(
                points[ edges[j].a ].x, points[ edges[j].a ].y,
                points[ edges[j].b ].x, points[ edges[j].b ].y
             );
          }
       }

       public void mouseEntered( MouseEvent e ) { }
       public void mouseExited( MouseEvent e ) { }
       public void mouseClicked( MouseEvent e ) { }
       public void mousePressed( MouseEvent e ) {
          mx = e.getX();
          my = e.getY();
          e.consume();
       }
       public void mouseReleased( MouseEvent e ) { }
       public void mouseMoved( MouseEvent e ) { }
       public void mouseDragged( MouseEvent e ) {
          // get the latest mouse position
          int new_mx = e.getX();
          int new_my = e.getY();

          // adjust angles according to the distance travelled by the mouse
          // since the last event
          azimuth -= new_mx - mx;
          elevation += new_my - my;

          // update the backbuffer
          drawWireframe( backg );

          // update our data
          mx = new_mx;
          my = new_my;

          repaint();
          e.consume();
       }

       public void update( Graphics g ) {
          g.drawImage( backbuffer, 0, 0, this );
          showStatus("Elev: "+elevation+" deg, Azim: "+azimuth+" deg");
       }

       public void paint( Graphics g ) {
          update( g );
       }
    }