How to rotate camera around origin?

Question

Hello!
I managed to create a view like:
TransformGroup cameraTransformGroup;
Transform3D cameraTransform3D = new Transform3D();
//Camera 10f from center at z-axis
          cameraTransform3D.set(new Vector3f(0.0f, 0.0f, 10.0f));
          cameraTransformGroup = simpleUniverse.getViewingPlatform().getViewPlatformTransform();
          cameraTransformGroup.setTransform(cameraTransform3D);
I mange to rotate the camera around it's own y-axis like:
rotY(cameraTransformGroup, Math.PI/32);
     public TransformGroup rotY(TransformGroup transformGroup, double angle)
          Transform3D oldTransform3D = new Transform3D();
          Transform3D rotationTransform3D = new Transform3D();
          transformGroup.getTransform(oldTransform3D);
          rotationTransform3D.rotY(angle);
          oldTransform3D.mul(rotationTransform3D);
          transformGroup.setTransform( oldTransform3D );
          return transformGroup;
Now I need something like:
public TransformGroup rotY(TransformGroup transformGroup, double angle, float anchor_x, float anchor_y, float anchor_z )
I really need some help with this code so if you guys got any nice solution please let me know!
Best regards
Fredrik

Answer 1

import javax.vecmath.*;
import java.awt.*;
import java.awt.event.*;
import javax.media.j3d.*;
import com.sun.j3d.utils.universe.*;
import com.sun.j3d.utils.geometry.*;
import com.sun.j3d.utils.picking.*;
import com.sun.j3d.utils.behaviors.mouse.*;
import java.applet.*;
import com.sun.j3d.utils.applet.MainFrame;
public class DataViewer extends Applet
     public static void main( String args[] )
          new MainFrame( new DataViewer(), 640, 480 );
     PointArray geom;
     PickCanvas pc;
     TextField text;
     public void init()
          setLayout( new BorderLayout() );
          GraphicsConfiguration gc = SimpleUniverse.getPreferredConfiguration();
          Canvas3D cv = new Canvas3D( gc );
          add( cv, BorderLayout.CENTER );
          cv.addMouseListener( new MouseAdapter()
               public void mouseClicked( MouseEvent event )
                    pick( event );
          text = new TextField();
          add( text, BorderLayout.SOUTH );
          BranchGroup bg = createSceneGraph( cv );
          bg.compile();
          SimpleUniverse su = new SimpleUniverse( cv );
          su.getViewingPlatform().setNominalViewingTransform();
          su.addBranchGraph( bg );
     private BranchGroup createSceneGraph( Canvas3D cv )
          BranchGroup root = new BranchGroup();
          TransformGroup spin = new TransformGroup();
          spin.setCapability( TransformGroup.ALLOW_TRANSFORM_READ );
          spin.setCapability( TransformGroup.ALLOW_TRANSFORM_WRITE );
          root.addChild( spin );
          // axes
          Transform3D tr = new Transform3D();
          tr.setScale( 0.3 );
          TransformGroup tg = new TransformGroup( tr );
          spin.addChild( tg );
          Axes axes = new Axes();
          tg.addChild( axes );
          // appearance
          Appearance ap = new Appearance();
          ap.setPointAttributes( new PointAttributes( 10f, true ) );
          // objects
          int n = 20;
          geom = new PointArray( n, PointArray.COORDINATES | PointArray.COLOR_4 );
          geom.setCapability( PointArray.ALLOW_COORDINATE_READ );
          geom.setCapability( PointArray.ALLOW_FORMAT_READ );
          geom.setCapability( PointArray.ALLOW_COLOR_READ );
          geom.setCapability( PointArray.ALLOW_COLOR_WRITE );
          geom.setCapability( PointArray.ALLOW_COUNT_READ );
          Point3f[] coords = new Point3f[n];
          Color4f[] colors = new Color4f[n];
          for ( int i = 0; i < n; i++ )
               coords[i] = new Point3f( (float)(Math.random()-0.5), (float)(Math.random()-0.5), (float)(Math.random()-0.5) );
               colors[i] = new Color4f( (float)(Math.random()), (float)(Math.random()), (float)(Math.random()), 1.0f );
          geom.setCoordinates( 0, coords );
          geom.setColors( 0, colors );
          BranchGroup bg = new BranchGroup();
          spin.addChild( bg );
          pc = new PickCanvas( cv, bg );
          pc.setTolerance( 5 );
          pc.setMode( PickTool.GEOMETRY_INTERSECT_INFO );
          Shape3D shape = new Shape3D( geom, ap );
          bg.addChild( shape );
          PickTool.setCapabilities( shape, PickTool.INTERSECT_TEST );
          shape.setCapability( Shape3D.ALLOW_GEOMETRY_READ );
          // rotation
          MouseRotate rotator = new MouseRotate( spin );
          BoundingSphere bounds = new BoundingSphere();
          rotator.setSchedulingBounds( bounds );
          spin.addChild( rotator );
          // translation
          MouseTranslate translator = new MouseTranslate( spin );
          translator.setSchedulingBounds( bounds );
          spin.addChild( translator );
          // zoom
          MouseZoom zoom = new MouseZoom( spin );
          zoom.setSchedulingBounds( bounds );
          spin.addChild( zoom );
          // background and light
          Background background = new Background( 1.0f, 1.0f, 1.0f );
          background.setApplicationBounds( bounds );
          root.addChild( background );
          AmbientLight light = new AmbientLight( true, new Color3f( Color.red ) );
          light.setInfluencingBounds( bounds );
          root.addChild( light );
          PointLight ptlight = new PointLight( new Color3f( Color.green ), new Point3f( 3.0f, 3.0f, 3.0f ), new Point3f( 1.0f, 0.0f, 0.0f ) );
          ptlight.setInfluencingBounds( bounds );
          root.addChild( ptlight );
          PointLight ptlight2 = new PointLight( new Color3f( Color.orange ), new Point3f( -2.0f, 2.0f, 2.0f ), new Point3f( 1.0f, 0.0f, 0.0f ) );
          ptlight2.setInfluencingBounds( bounds );
          root.addChild( ptlight2 );
          return root;
     private void pick( MouseEvent event )
          Color4f color = new Color4f();
          pc.setShapeLocation( event );
          PickResult[] results = pc.pickAll();
          for ( int i = 0; (results != null) && (i < results.length); i++ )
               PickIntersection inter = results.getIntersection( 0 );
               Point3d pt = inter.getClosestVertexCoordinates();
               int[] ind = inter.getPrimitiveCoordinateIndices();
               text.setText( "vertex " + ind[0] + ": (" + pt.x + ", " + pt.y + ", " + pt.z + ")" );
               geom.getColor( ind[0], color );
               color.x = 1.0f - color.x;
               color.y = 1.0f - color.y;
               color.z = 1.0f - color.z;
               if ( color.w > 0.8 )
                    color.w = 0.5f;
               else
                    color.w = 1.0f;
               geom.setColor( ind[0], color );