// Java 3Dテスト用アプレット
// NormalTest.java
//   Copyright (c) 1999 ENDO Yasuyuki
//                      mailto:yasuyuki@javaopen.org
//                      http://www.javaopen.org/j3dbook/index.html

import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import javax.media.j3d.*;
import javax.vecmath.*;
import com.sun.j3d.utils.applet.MainFrame;
import com.sun.j3d.utils.universe.SimpleUniverse;

public class NormalTest extends Applet {
  private SimpleUniverse universe = null;
  private BranchGroup scene = null;
  private Shape3D nshape = null;

  public NormalTest() {
    this.setLayout(new BorderLayout());

    Panel panel = new Panel();
    this.add(panel, BorderLayout.SOUTH);
    
    Checkbox check = new Checkbox("Normals", true);
    check.addItemListener( new ItemListener() {
      public void itemStateChanged(ItemEvent e) {
	int state = e.getStateChange();
	universe.getLocale().removeBranchGraph(scene);
	if (state == ItemEvent.SELECTED) {
	  addChild(scene, nshape);
	} else if (state == ItemEvent.DESELECTED) {
	  removeChild(scene, nshape);
	}
	universe.addBranchGraph(scene);
      }
    });
    panel.add(check);    

    GraphicsConfiguration config =
      SimpleUniverse.getPreferredConfiguration();
    Canvas3D canvas = new Canvas3D(config);
    this.add(canvas, BorderLayout.CENTER);

    universe = new SimpleUniverse(canvas);
    universe.getViewingPlatform().setNominalViewingTransform();

    scene = createSceneGraph();

    universe.addBranchGraph(scene);
  }

  private BranchGroup createSceneGraph() {
    BranchGroup root = new BranchGroup();
    root.setCapability(BranchGroup.ALLOW_DETACH);

    root.addChild( createLight() );

    Point3d[] vertices = new Point3d[3];
    
    vertices[0] = new Point3d(-0.4, -0.8, 0.0);
    vertices[1] = new Point3d(0.5, -0.4, 0.0);
    vertices[2] = new Point3d(-0.6, 0.7, -0.4);
    
    Vector3f faceNormal = calcFaceNormal(vertices);

    Vector3f[] normals = new Vector3f[3];
    
    for (int i=0; i<normals.length; i++) normals[i] = faceNormal;
    
    TriangleArray geometry =
      new TriangleArray( vertices.length,
                         GeometryArray.COORDINATES |
                         GeometryArray.NORMALS);
    geometry.setCoordinates(0, vertices);
    geometry.setNormals(0, normals);
    
    Shape3D shape = new Shape3D(geometry);
    shape.setAppearance( createAppearance() );
    
    root.addChild(shape);

    NormalRender nrender = new NormalRender(geometry, 0.5f);
    nshape = new Shape3D(nrender.getLineArray());
    root.addChild(nshape);

    return root;
  }

  private Light createLight() {
    DirectionalLight light =
      new DirectionalLight( new Color3f(1.0f, 1.0f, 1.0f),
                            new Vector3f(0.0f, 0.0f, -1.0f) );
    BoundingSphere bounds = new BoundingSphere(new Point3d(), 100.0);
    light.setInfluencingBounds(bounds);
    
    return light;
  }

  private Vector3f calcFaceNormal(Point3d[] vertices) {
    double ax = vertices[2].x - vertices[1].x;
    double ay = vertices[2].y - vertices[1].y;
    double az = vertices[2].z - vertices[1].z;
    double bx = vertices[0].x - vertices[1].x;
    double by = vertices[0].y - vertices[1].y;
    double bz = vertices[0].z - vertices[1].z;
    
    double nx = ay * bz - az * by;
    double ny = az * bx - ax * bz;
    double nz = ax * by - ay * bx;

    Vector3f normal = new Vector3f( (float)nx,
                                    (float)ny,
                                    (float)nz );
    normal.normalize();

    //DEBUG
    System.out.println("nx=" + normal.x + ", ny=" + normal.y + ", nz=" + normal.z);

    return  normal;
  }

  private Appearance createAppearance() {
    Material mat = new Material();
    mat.setDiffuseColor( new Color3f(0.0f, 0.0f, 1.0f) );
    mat.setShininess(128.0f);
    
    Appearance ap = new Appearance();
    ap.setMaterial(mat);
    
    return ap;
  }

  private void addChild(Group group, Node node) {
    for (int i=0; i<group.numChildren(); i++) if (node == group.getChild(i)) return;
    group.addChild(node);
  }

  private void removeChild(Group group, Node node) {
    for (int i=0; i<group.numChildren(); i++) {
      if (node == group.getChild(i)) group.removeChild(i);
    }
  }

  public static void main(String[] args) {
    NormalTest applet = new NormalTest();
    MainFrame frame = new MainFrame(applet, 500, 500);
  }
}