I'm using simply
setCullFace(PolygonAttributes.CULL_FRONT);
there's no need to manipulate the geometry.
If you're using directional lights, you have to mirror the light sources,
too.
And then you have to make sure that the original lights will only affect the
original objects,
and the mirrored lights will only affect the mirrored objects:
DirectionalLight.setInfluencingBounds(...)
(if you forget this, the mirrored objects will be lighted by both light
sources).
Hope this helps,
Peter
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
> Sent: Donnerstag, 2. Januar 2003 21:35
> To: [EMAIL PROTECTED]
> Subject: [JAVA3D] mirroring problem
>
>
> I try to mirror one element along Z axis. I made it with such a matrix
>
> 1 0 0 0
> 0 1 0 0
> 0 0 -1 0
> 0 0 0 1
>
> The problem is, after mirroring, culling behavies exactly
> oposite to its
> expected behaviour: back side of polygons is seen and front side not.
> Additionaly, light source seens to light in opposite direction too.
>
> I tried to negate normals, without efect.
> Only if I disable culling it all polygons are seen, but lighting works
> still incorrect.
>
> Please try test programm, it is one half of the cube.
>
>
> import java.awt.GraphicsConfiguration;
>
> import javax.media.j3d.AmbientLight;
> import javax.media.j3d.Appearance;
> import javax.media.j3d.BoundingSphere;
> import javax.media.j3d.BranchGroup;
> import javax.media.j3d.Canvas3D;
> import javax.media.j3d.ColoringAttributes;
> import javax.media.j3d.DirectionalLight;
> import javax.media.j3d.LineArray;
> import javax.media.j3d.Material;
> import javax.media.j3d.PolygonAttributes;
> import javax.media.j3d.QuadArray;
> import javax.media.j3d.Shape3D;
> import javax.media.j3d.Transform3D;
> import javax.media.j3d.TransformGroup;
> import javax.swing.JFrame;
> import javax.vecmath.Color3f;
> import javax.vecmath.Matrix4d;
> import javax.vecmath.Point3d;
> import javax.vecmath.Vector3d;
> import javax.vecmath.Vector3f;
>
> import com.sun.j3d.utils.behaviors.keyboard.KeyNavigatorBehavior;
> import com.sun.j3d.utils.universe.SimpleUniverse;
>
> public class MirrorTest extends JFrame {
>
> private static Point3d x0y0z0 =new Point3d(0,0,0);
> private static Point3d x0y0z1 =new Point3d(0,0,1);
> private static Point3d x0y1z0 =new Point3d(0,1,0);
> private static Point3d x0y1z1 =new Point3d(0,1,1);
> private static Point3d x1y0z0 =new Point3d(1,0,0);
> private static Point3d x1y0z1 =new Point3d(1,0,1);
> private static Point3d x1y1z0 =new Point3d(1,1,0);
> private static Point3d x1y1z1 =new Point3d(1,1,1);
>
> public MirrorTest(){
> setDefaultCloseOperation(EXIT_ON_CLOSE);
> GraphicsConfiguration config =
> SimpleUniverse.getPreferredConfiguration();
> Canvas3D canvas3D = new Canvas3D(config);
> getContentPane().add(canvas3D);
>
> SimpleUniverse universe = new
> SimpleUniverse(canvas3D);
>
> universe.getViewingPlatform().setNominalViewingTransform();
>
> //prepare custom Geometry
> QuadArray geometry = new QuadArray(3*4,
> QuadArray.COORDINATES | QuadArray.NORMALS);
> boolean negateNormalsX = false;
> boolean negateNormalsY = false;
> boolean negateNormalsZ = false;
> int i=0;
> Vector3f normal;
> //z1
> normal = new Vector3f(0,0,1);
> if(negateNormalsZ) normal.z = -normal.z;
> for(int k = i; k<i+4; k++){
> geometry.setNormal(k, normal);
> }
> geometry.setCoordinate(i++, x0y0z1);
> geometry.setCoordinate(i++, x1y0z1);
> geometry.setCoordinate(i++, x1y1z1);
> geometry.setCoordinate(i++, x0y1z1);
> //x1
> normal = new Vector3f(1,0,0);
> if(negateNormalsX) normal.x = -normal.x;
> for(int k = i; k<i+4; k++){
> geometry.setNormal(k, normal);
> }
> geometry.setCoordinate(i++, x1y0z0);
> geometry.setCoordinate(i++, x1y1z0);
> geometry.setCoordinate(i++, x1y1z1);
> geometry.setCoordinate(i++, x1y0z1);
> //y1
> normal = new Vector3f(0,1,0);
> if(negateNormalsY) normal.y = -normal.y;
> for(int k = i; k<i+4; k++){
> geometry.setNormal(k, normal);
> }
> geometry.setCoordinate(i++, x0y1z0);
> geometry.setCoordinate(i++, x0y1z1);
> geometry.setCoordinate(i++, x1y1z1);
> geometry.setCoordinate(i++, x1y1z0);
>
>
> //make scene
> BranchGroup scene = new BranchGroup();
>
> //add navigator
> TransformGroup vpTG =
> universe.getViewingPlatform().getViewPlatformTransform();
> BoundingSphere boundingSphere = new
> BoundingSphere( new Point3d(),1000.0);
> KeyNavigatorBehavior keyboardNavigator = new
> KeyNavigatorBehavior(vpTG);
> keyboardNavigator.setSchedulingBounds(boundingSphere);
> scene.addChild(keyboardNavigator);
>
>
> //set lighting
> BoundingSphere lightBounds = new BoundingSphere();
> lightBounds.setCenter(new Point3d(0,0,0));
> lightBounds.setRadius(100);
>
> AmbientLight ambientLight = new
> AmbientLight(new Color3f(0.3f,0.3f,0.3f));
> ambientLight.setInfluencingBounds(new
> BoundingSphere(lightBounds));
> scene.addChild(ambientLight);
>
> DirectionalLight directLight = new DirectionalLight();
> directLight.setInfluencingBounds(lightBounds);
> scene.addChild(directLight);
>
> //add box with mirror transformation
> Appearance ap = new Appearance();
> Color3f black = new Color3f(0,0,0);
> Color3f green = new Color3f(0,1f,0);
> Material material = new Material(green,
> black, green, green, 64);
> ap.setMaterial(material);
> PolygonAttributes pa = new PolygonAttributes();
> pa.setCullFace(PolygonAttributes.CULL_FRONT);
> pa.setBackFaceNormalFlip(true);
> //ap.setPolygonAttributes(pa);
> Shape3D shape = new Shape3D(geometry, ap);
> Transform3D mirror = new Transform3D();
> mirror.set(new Matrix4d( new double [] {
> 1, 0, 0, 0,
> 0, 1, 0, 0,
> 0, 0, -1,0,
> 0, 0, 0, 1
> }));
> TransformGroup tg = new TransformGroup(mirror);
> /*
> Transform3D rot = new Transform3D();
> rot.rotX(-Math.PI);
> TransformGroup tg = new TransformGroup(rot);
> */
>
> tg.addChild(shape);
> tg.addChild(new Axies(3, 3, 3));
> scene.addChild(tg);
>
> universe.addBranchGraph(scene);
> setSize(500, 500);
> }
>
> public static void main(String[] args){
> new MirrorTest().setVisible(true);
> }
>
> private class Axies extends BranchGroup {
> public Axies(double lengthX, double lengthY,
> double lengthZ){
> setCapability(ALLOW_DETACH);
> Color3f colorX = new Color3f(1, 0, 0);
> Color3f colorY = new Color3f(0, 1, 0);
> Color3f colorZ = new Color3f(0, 0, 1);
> Point3d zero = new Point3d(0,0,0);
>
> LineArray lines = new LineArray(6,
> LineArray.COORDINATES | LineArray.COLOR_3);
> int i=0;
> //axis X
> lines.setColor(i, colorX);
> lines.setCoordinate(i++, zero);
> lines.setColor(i, colorX);
> lines.setCoordinate(i++, new
> Point3d(lengthX, 0, 0));
> //axis Y
> lines.setColor(i, colorY);
> lines.setCoordinate(i++, zero);
> lines.setColor(i, colorY);
> lines.setCoordinate(i++, new
> Point3d(0, lengthY, 0));
> //axis Z
> lines.setColor(i, colorZ);
> lines.setCoordinate(i++, zero);
> lines.setColor(i, colorZ);
> lines.setCoordinate(i++, new
> Point3d(0, 0, lengthZ));
>
> addChild(new Shape3D(lines));
>
> //prepare arrow Geometry
> LineArray arrow = new LineArray(2*4,
> LineArray.COORDINATES);
> i=0;
> arrow.setCoordinate(i++, zero);
> arrow.setCoordinate(i++, new
> Point3d(-2, 1, 0));
> arrow.setCoordinate(i++, zero);
> arrow.setCoordinate(i++, new
> Point3d(-2, 0, 1));
> arrow.setCoordinate(i++, zero);
> arrow.setCoordinate(i++, new
> Point3d(-2, -1, 0));
> arrow.setCoordinate(i++, zero);
> arrow.setCoordinate(i++, new
> Point3d(-2, 0, -1));
>
> //prepare X character
> LineArray charX = new LineArray(2*2,
> LineArray.COORDINATES);
> i=0;
> charX.setCoordinate(i++, new
> Point3d(-1, -2, 0));
> charX.setCoordinate(i++, new
> Point3d(1, 2, 0));
> charX.setCoordinate(i++, new
> Point3d(1, -2, 0));
> charX.setCoordinate(i++, new
> Point3d(-1, 2, 0));
> //prepare Y character
> LineArray charY = new LineArray(3*2,
> LineArray.COORDINATES);
> i=0;
> charY.setCoordinate(i++, new
> Point3d(0, -2, 0));
> charY.setCoordinate(i++, new
> Point3d(0, 0, 0));
> charY.setCoordinate(i++, new
> Point3d(0, 0, 0));
> charY.setCoordinate(i++, new
> Point3d(-1, 2, 0));
> charY.setCoordinate(i++, new
> Point3d(0, 0, 0));
> charY.setCoordinate(i++, new
> Point3d(1, 2, 0));
>
> LineArray charZ = new LineArray(3*2,
> LineArray.COORDINATES);
> i=0;
> charZ.setCoordinate(i++, new
> Point3d(-1, 0, -2));
> charZ.setCoordinate(i++, new
> Point3d(1, 0, -2));
> charZ.setCoordinate(i++, new
> Point3d(1, 0, -2));
> charZ.setCoordinate(i++, new
> Point3d(-1, 0, 2));
> charZ.setCoordinate(i++, new
> Point3d(-1, 0, 2));
> charZ.setCoordinate(i++, new
> Point3d(1, 0, 2));
>
> //make arrows
> //calculate arrow size
> double arrowSize = (lengthX + lengthY
> + lengthZ ) / 3 / 20;
> Transform3D tr = new Transform3D();
> TransformGroup tg;
> Appearance ap;
> ColoringAttributes ca;
>
> //X arrow
> tr.set(arrowSize, new Vector3d(lengthX, 0,0));
> tg=new TransformGroup(tr);
> ap = new Appearance();
> ca = new ColoringAttributes(colorX,
> ColoringAttributes.FASTEST);
> ap.setColoringAttributes(ca);
> tg.addChild(new Shape3D(arrow, ap));
> addChild(tg);
> //X character
> tr.set(arrowSize/2, new
> Vector3d(lengthX, arrowSize*2, 0));
> tg = new TransformGroup(tr);
> tg.addChild(new Shape3D(charX, ap));
> addChild(tg);
>
> //Y arrow
> tr.set(arrowSize, new Vector3d(0, lengthY,0));
> Transform3D rotY = new Transform3D();
> rotY.rotZ(Math.PI/2);
> tr.mul(rotY);
> tg=new TransformGroup(tr);
> ap = new Appearance();
> ca = new ColoringAttributes(colorY,
> ColoringAttributes.FASTEST);
> ap.setColoringAttributes(ca);
> tg.addChild(new Shape3D(arrow, ap));
> addChild(tg);
> //Y character
> tr.set(arrowSize/2, new Vector3d(-
> arrowSize*2, lengthY, 0));
> tg = new TransformGroup(tr);
> tg.addChild(new Shape3D(charY, ap));
> addChild(tg);
>
> //Z arrow
> tr.set(arrowSize, new Vector3d(0, 0,
> lengthZ));
> Transform3D rotZ = new Transform3D();
> rotZ.rotY(-Math.PI/2);
> tr.mul(rotZ);
> tg=new TransformGroup(tr);
> ap = new Appearance();
> ca = new ColoringAttributes(colorZ,
> ColoringAttributes.FASTEST);
> ap.setColoringAttributes(ca);
> tg.addChild(new Shape3D(arrow, ap));
> addChild(tg);
> //Z character
> tr.set(arrowSize/2, new Vector3d(-
> arrowSize*2, 0, lengthZ));
> tg = new TransformGroup(tr);
> tg.addChild(new Shape3D(charZ, ap));
> addChild(tg);
> }
> }
> }
>
>
>
> Radek Wisniewski
>
> ==============================================================
> =============
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> send email to
> [EMAIL PROTECTED] and include in the body of the message "help".
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