import javax.media.j3d.*;
import javax.vecmath.*;

public class BasicUniverse extends Object
{
  VirtualUniverse universe;
  Locale locale;
  BranchGroup viewPlatformRoot;
  TransformGroup viewPlatformTransform;
  ViewPlatform viewPlatform;
  View view;
  Canvas3D canvas;
  float zViewDistance;

  public BasicUniverse(Canvas3D extCanvas,float zViewDist) {
    canvas = extCanvas;
    zViewDistance = zViewDist;
    universe = new VirtualUniverse();
    locale = new Locale(universe);
    viewPlatformRoot = new BranchGroup();
    viewPlatformTransform = new TransformGroup();
    viewPlatformTransform.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);
    viewPlatformTransform.setCapability(TransformGroup.ALLOW_TRANSFORM_READ);
    setupViewPlatform();
    viewPlatformRoot.addChild(viewPlatformTransform);
    setupView(extCanvas);
    view.attachViewPlatform(viewPlatform);
    locale.addBranchGraph(viewPlatformRoot);
  }

  private void setupView(Canvas3D extCanvas)
  {
    view = new View();
    view.addCanvas3D(extCanvas);
    view.setPhysicalBody(new PhysicalBody());
    view.setPhysicalEnvironment(new PhysicalEnvironment());
  }

  /**
   * Translates the view platform back by zViewDistance metres.
   * No other transform applied.
   */
  private void setupViewPlatform()
  {
    viewPlatform = new ViewPlatform();
    setViewingDistance(zViewDistance);
    viewPlatformTransform.addChild(viewPlatform);
  }
  public void setViewingDistance(float viewDistance)
  {
    zViewDistance = viewDistance;
    Transform3D transform = new Transform3D();
    transform.set(new Vector3f(0.0f, 0.0f, zViewDistance));
    viewPlatformTransform.setTransform(transform);
  }


  public TransformGroup getViewPlatformTransform()
  {
    return viewPlatformTransform;
  }

  public View getView()
  {
    return view;
  }

  public void addBranchGraph(BranchGroup bg) {
    locale.addBranchGraph(bg);
  }
}