java - 纹理映射颠倒了! Java3D

Question

我可以使用一些额外的眼睛来帮助我了解为什么我的纹理贴图在我的对象上是相反的。它向后打印——就像在镜子里看到它一样。我曾怀疑也许反转索引会有所帮助，但这只是改变了它的映射位置，而没有反转反转。

    public class MobiusBanner extends Applet {

        public static void main(String[] args) {
            new MainFrame(new MobiusBanner(), 800, 600);
        }

        @Override
        public void init() {
            GraphicsConfiguration gc = SimpleUniverse.getPreferredConfiguration();
            Canvas3D canvas = new Canvas3D(gc);
            this.setLayout(new BorderLayout());
            this.add(canvas, BorderLayout.CENTER);
            SimpleUniverse su = new SimpleUniverse(canvas);
            su.getViewingPlatform().setNominalViewingTransform();
            BranchGroup bg = createSceneGraph();
            bg.compile();
            su.addBranchGraph(bg);
        }

        private BranchGroup createSceneGraph() {
            BranchGroup root = new BranchGroup();
            Shape3D shape = new Shape3D();
            shape.setGeometry(mobius().getIndexedGeometryArray());

            //Scaling transform
            Transform3D tr = new Transform3D();
            tr.setScale(0.5);

            //Spin transform group
            TransformGroup spin = new TransformGroup();
            spin.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);
            spin.setCapability(TransformGroup.ALLOW_TRANSFORM_READ);
            root.addChild(spin);

            //Set appearance
            Appearance ap = createTextureAppearance();
            ap.setPolygonAttributes(new PolygonAttributes(PolygonAttributes.POLYGON_FILL,
            PolygonAttributes.CULL_BACK, 0));

            //Set materials
            Material mat = new Material();
            mat.setLightingEnable(true);
            mat.setShininess(30);
            ap.setMaterial(mat);

            //Overarching Transform group
            TransformGroup tg = new TransformGroup(tr);
            tg.addChild(shape);
            spin.addChild(tg);
            shape.setAppearance(ap);

            //Set rotation
            MouseRotate rotator = new MouseRotate(spin);
            BoundingSphere bounds = new BoundingSphere();
            rotator.setSchedulingBounds(bounds);
            spin.addChild(rotator);

            //Set translation
            MouseTranslate translator = new MouseTranslate(spin);
            translator.setSchedulingBounds(bounds);
            spin.addChild(translator);

            //Set zoom
            MouseZoom zoom = new MouseZoom(spin);
            zoom.setSchedulingBounds(bounds);
            spin.addChild(zoom);


            //Set background
            Background background = new Background(1.0f, 1.0f, 1.0f);
            background.setApplicationBounds(bounds);
            root.addChild(background);

            f//Set lighting
            AmbientLight light = new AmbientLight(true, new Color3f(Color.BLACK));
            light.setInfluencingBounds(bounds);
            root.addChild(light);

            PointLight ptlight = new PointLight(new Color3f(Color.white),
                    new Point3f(0.5f, 0.5f, 1f),
                    new Point3f(1f, 0.2f, 0f));
            ptlight.setInfluencingBounds(bounds);
            root.addChild(ptlight);

            return root;
        }//Close branchgroup method

        //Create the Mobius shape
        private GeometryInfo mobius() {
            int m = 100; //number of row points
            int n = 100; //number of col points
            int p = 4 * ((m - 1) * (n - 1)); //faces * points per face

            IndexedQuadArray iqa = new IndexedQuadArray(m * n,         
    GeometryArray.COORDINATES | GeometryArray.TEXTURE_COORDINATE_2, p);
            Point3d[] vertices = new Point3d[m * n];

    int index = 0;

            //Create vertices
            for (int i = 0; i < m; i++) {
                for (int j = 0; j < n; j++) {
                    double u = i * (4 * (Math.PI)) / (m - 1);
                    double v = -0.3 + (j * (0.6 / (n - 1)));
                    double x = (1 + v * Math.cos(u / 2)) * Math.cos(u);
                    double y = (1 + v * Math.cos(u / 2)) * Math.sin(u);
                    double z = v * Math.sin(u / 2);
                    vertices[index] = new Point3d(x, y, z);
                    index++;
                }//close nested for loop
            }//close for loop

            index = 0;
            //set texture coordinates
            TexCoord2f[] tex = new TexCoord2f[m * n];
            for (int i = 0; i < m; i++) {
                for (int j = 0; j < n; j++) {
                    tex[index] = new TexCoord2f();
                    tex[index] = new TexCoord2f(i * 1f / m, j * 1f / n);
                    index++;
                }
            }

            iqa.setCoordinates(0, vertices);
            iqa.setTextureCoordinates(0, 0, tex);
            index = 0;

            //set index for coordinates
            int[] texIndices = new int[p];
            for (int i = 0; i < m - 1; i++) {
                for (int j = 0; j < n - 1; j++) {
                    iqa.setCoordinateIndex(index, i * m + j);
                    texIndices[index] = i * m + j;
                    index++;
                    iqa.setCoordinateIndex(index, i * m + j + 1);
                    texIndices[index] = i * m + j + 1;
                    index++;
                    iqa.setCoordinateIndex(index, (i + 1) * m + j + 1);
                    texIndices[index] = (i + 1) * m + j + 1;
                    index++;
                    iqa.setCoordinateIndex(index, (i + 1) * m + j);
                    texIndices[index] = (i + 1) * m + j;
                    index++;
                }//close nested for loop
            }//close for loop

            iqa.setTextureCoordinateIndices(0, 0, texIndices);

            //create geometry info and generate normals for shape
            GeometryInfo gi = new GeometryInfo(iqa);
            NormalGenerator ng = new NormalGenerator();
            ng.generateNormals(gi);
            return gi;
        }

        Appearance createTextureAppearance() {
            Appearance ap = new Appearance();
            BufferedImage bi = new BufferedImage(1024, 128, 
            BufferedImage.TYPE_INT_ARGB);
            Graphics2D g2 = (Graphics2D) bi.getGraphics();
            g2.setColor(Color.white);
            g2.fillRect(0, 0, 1024, 128);
            g2.setFont(new Font("Serif", Font.BOLD, 36));
            g2.setColor(new Color(200, 0, 0));
            g2.drawString("Mobius Strip", 0, 100);
            ImageComponent2D image = new ImageComponent2D(ImageComponent2D.FORMAT_RGBA, bi);
            Texture2D texture = new Texture2D(Texture.BASE_LEVEL, Texture.RGBA,         
            image.getWidth(), image.getHeight());
            texture.setImage(0, image);
            texture.setMagFilter(Texture.BASE_LEVEL_LINEAR);
            ap.setTexture(texture);

            //Combine Texture and Lighting
            TextureAttributes textatt = new TextureAttributes();
            textatt.setTextureMode(TextureAttributes.COMBINE);
            ap.setTextureAttributes(textatt);
            ap.setMaterial(new Material());
            return ap;

                }
    }

Answer 1

您只想反转其中一个纹理坐标，而不是同时反转两者。尝试改变

tex[index] = new TexCoord2f(i * 1f / m, j * 1f / n);

至

tex[index] = new TexCoord2f((m-1-i) * 1f / m, j * 1f / n);

或

tex[index] = new TexCoord2f(i * 1f / m, (n-1-j) * 1f / n);