java3d中的面部着色

我喜欢这个解决方案。“每个顶点的颜色”实际上是每个顶点的参考，因此每个顶点的每个面都可以具有不同的颜色。

这是一个有效的示例（非常小）。

    package examples;    import javax.media.j3d.Alpha;    import javax.media.j3d.AmbientLight;    import javax.media.j3d.Appearance;    import javax.media.j3d.BoundingSphere;    import javax.media.j3d.Bounds;    import javax.media.j3d.BranchGroup;    import javax.media.j3d.DirectionalLight;    import javax.media.j3d.GeometryArray;    import javax.media.j3d.IndexedTriangleArray;    import javax.media.j3d.Node;    import javax.media.j3d.PolygonAttributes;    import javax.media.j3d.RotationInterpolator;    import javax.media.j3d.Shape3D;    import javax.media.j3d.Transform3D;    import javax.media.j3d.TransformGroup;    import javax.media.j3d.View;    import javax.media.j3d.ViewPlatform;    import javax.vecmath.Color3f;    import javax.vecmath.Point3d;    import javax.vecmath.Vector3f;    import com.sun.j3d.utils.geometry.GeometryInfo;    import com.sun.j3d.utils.geometry.NormalGenerator;    import com.sun.j3d.utils.universe.MultiTransformGroup;    import com.sun.j3d.utils.universe.SimpleUniverse;    import com.sun.j3d.utils.universe.ViewingPlatform;    public class Example {      public static void main(final String[] args) {        new Example();      }      public Example() {        final SimpleUniverse universe = new SimpleUniverse();        final BranchGroup group = new BranchGroup();        final TransformGroup tg = new TransformGroup();        final BoundingSphere bounds = new BoundingSphere(new Point3d(0.0, 0.0, 0.0), 100.0);        final Node blob = createMonster();        { //to enable rotation          tg.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);          tg.setCapability(TransformGroup.ALLOW_TRANSFORM_READ);        }        // Create rotation to see all sides of the object        final Transform3D btrans = new Transform3D();        btrans.rotX(1);        final Transform3D ztrans = new Transform3D();        ztrans.rotZ(-1);        btrans.mul(ztrans);        final RotationInterpolator ri = createRotation(tg, bounds, btrans, 7000);        tg.addChild(ri);        tg.addChild(blob);        //        group.addChild(tg);        //        addLight(group, new Color3f(1f, 1f, 0f), new Vector3f(4.0f, +7.0f, -12.0f));        addLight(group, new Color3f(1f, 1f, 1f));        //        final ViewingPlatform viewingPlatform = universe.getViewingPlatform();        final ViewPlatform view = viewingPlatform.getViewPlatform();        view.setViewAttachPolicy(View.NOMINAL_SCREEN);        viewingPlatform.setNominalViewingTransform();        final MultiTransformGroup mtg = viewingPlatform.getMultiTransformGroup();        final TransformGroup vtg = mtg.getTransformGroup(0);        final Transform3D t1 = btrans;        vtg.getTransform(t1);        t1.setScale(2);        vtg.setTransform(t1);        group.compile();        // add the group of objects to the Universe        universe.addBranchGraph(group);      }      private Node createMonster() {        final Shape3D child = createShape();        final Appearance fillAppNode = new Appearance();        final PolygonAttributes pAtt = new PolygonAttributes();        // avoid trouble with clockwise faces        pAtt.setCullFace(PolygonAttributes.CULL_NONE);        pAtt.setBackFaceNormalFlip(true);        fillAppNode.setPolygonAttributes(pAtt);        child.setAppearance(fillAppNode);        return child;      }      private Shape3D createShape() {        final Point3d[] points = new Point3d[] {//        new Point3d(-1, 1, 0), // new Point3d(1, 1, 0), // new Point3d(1, -1, 0), // new Point3d(-1, -1, 0), // new Point3d(0, 0, 1), //        };        final int[] idxs = new int[] {// the triangle faces        0, 1, 2,// 2, 3, 0,// 1, 0, 4,// 1, 2, 4,// 2, 3, 4,// 3, 0, 4 };        final IndexedTriangleArray ita = new IndexedTriangleArray(points.length, GeometryArray.COORDINATES | GeometryArray.COLOR_3, idxs.length);        ita.setCoordinates(0, points);        ita.setCoordinateIndices(0, idxs);        //per vertex colors really are per vertex reference        //so each vertex can have a different color for each of its faces        final Color3f[] colors = new Color3f[] {//        new Color3f(1, 0, 1),// new Color3f(0, 1, 0),// new Color3f(0, 0, 1),// new Color3f(1, 1, 0),// new Color3f(1, 1, 1),//        };        ita.setColors(0, colors);        ita.setColorIndices(0, idxs);        ita.setColorIndices(0, new int[] { 0, 0, 0, 1, 1, 1 });        //        final GeometryInfo gi = new GeometryInfo(ita);        //also generate normal vectors so that the surface can be light        final NormalGenerator normalGenerator = new NormalGenerator();        normalGenerator.generateNormals(gi);        final GeometryArray geometryArray = gi.getGeometryArray();        return new Shape3D(geometryArray);      }      private RotationInterpolator createRotation(final TransformGroup objScale, final Bounds bounds,          final Transform3D btrans, final long milis) {        final Alpha alpha = new Alpha(-1, Alpha.INCREASING_ENABLE, 0, 0, milis, 0, 0, 0, 0, 0);        final RotationInterpolator ri = new RotationInterpolator(alpha, objScale, btrans, 0.0f, (float) Math.PI * 2.0f);        ri.setSchedulingBounds(bounds);        return ri;      }      private void addLight(final BranchGroup group, final Color3f light1Color, final Vector3f ligthDirection) {        {          final BoundingSphere bounds = new BoundingSphere(new Point3d(0.0, 0.0, 0.0), 100.0);          final DirectionalLight light1 = new DirectionalLight(light1Color, ligthDirection);          light1.setInfluencingBounds(bounds);          group.addChild(light1);        }      }      private void addLight(final BranchGroup group, final Color3f light1Color) {        {          final BoundingSphere bounds = new BoundingSphere(new Point3d(0.0, 0.0, 0.0), 100.0);          final AmbientLight light1 = new AmbientLight(light1Color);          light1.setInfluencingBounds(bounds);          group.addChild(light1);        }      }    }