How to create hollow cylinder and truncated cone w

问题:

I'm learning JavaFX 3D. So far I have not found a way how I can create the following objects:

• Hollow cylinder
• Truncated cone

Can someone please give me a short code example?

Any help will be appreciated. :-)

回答1:

I know it's an old question but I've been trying to solve similar problem so here is my solution for truncated cone:

public class Cone extends Group{

int rounds = 360;
int r1 = 100;
int r2 = 50;
int h = 100;

public Cone() {
    Group cone = new Group();
    PhongMaterial material = new PhongMaterial(Color.BLUE);

    float[] points = new float[rounds *12];
    float[] textCoords = {
            0.5f, 0,
            0, 1,
            1, 1
    };
    int[] faces = new int[rounds *12];

    for(int i= 0; i<rounds; i++){
        int index = i*12;
        //0
        points[index] = (float)Math.cos(Math.toRadians(i))*r2;
        points[index+1] = (float)Math.sin(Math.toRadians(i))*r2;
        points[index+2] = h/2;
        //1
        points[index+3] = (float)Math.cos(Math.toRadians(i))*r1;
        points[index+4] = (float)Math.sin(Math.toRadians(i))*r1;
        points[index+5] = -h/2;
        //2
        points[index+6] = (float)Math.cos(Math.toRadians(i+1))*r1;
        points[index+7] = (float)Math.sin(Math.toRadians(i+1))*r1;
        points[index+8] = -h/2;
        //3
        points[index+9] = (float)Math.cos(Math.toRadians(i+1))*r2;
        points[index+10] = (float)Math.sin(Math.toRadians(i+1))*r2;
        points[index+11] = h/2;        
    }

    for(int i = 0; i<rounds ; i++){
        int index = i*12;
        faces[index]=i*4;
        faces[index+1]=0;
        faces[index+2]=i*4+1;
        faces[index+3]=1;
        faces[index+4]=i*4+2;
        faces[index+5]=2;

        faces[index+6]=i*4;
        faces[index+7]=0;
        faces[index+8]=i*4+2;
        faces[index+9]=1;
        faces[index+10]=i*4+3;
        faces[index+11]=2;
    }

    TriangleMesh mesh = new TriangleMesh();
    mesh.getPoints().addAll(points);
    mesh.getTexCoords().addAll(textCoords);
    mesh.getFaces().addAll(faces);

    Cylinder circle1 = new Cylinder(r1, 0.1);
    circle1.setMaterial(material);
    circle1.setTranslateZ( -h / 2);
    circle1.setRotationAxis(Rotate.X_AXIS);
    circle1.setRotate(90);

    Cylinder circle2 = new Cylinder(r2, 0.1);
    circle2.setMaterial(material);
    circle2.setTranslateZ( h / 2);
    circle2.setRotationAxis(Rotate.X_AXIS);
    circle2.setRotate(90);


     MeshView meshView = new MeshView();
    meshView.setMesh(mesh);
    meshView.setMaterial(material);
    //meshView.setDrawMode(DrawMode.LINE);
    cone.getChildren().addAll(meshView);
    Rotate r1 = new Rotate(90, Rotate.X_AXIS);
    cone.getTransforms().add(r1);
    getChildren().addAll(cone);
}

Hope this helps someone in the future!

回答2:

The first - create a cylinder, and use two different appearance objects - one for cylinder, side, and one for the two bases. For the two bases, use an invisible appearance (rendering attributes). For info on how to set different appearances to bases, set thread: http://forum.java.sun.com/thread.jspa?threadID=663825&tstart=0

The second - use a clipping plane to clip of the bottom and top of the cylinder, and you have a hollow cylinder.

Those two methods will give you a hollow cylinder with a COMPLETELY empty interior.

If you're looking to have walls with a given thickness, there is a boolean operations set available on the internet. Create a large cylinder, and subtract a smaller cylinder. For info on the boolean op set, set this thread: http://forum.java.sun.com/thread.jspa?threadID=658612&tstart=0

Finally, it's really pretty easy to create a cylinder's geometry yourself, and it can be automated really easily with a loop. I would create four separate geometries: one for the inner cylinder with the rendered faces on the inside, one for the outer cylinder, with the rendered faces on the outside, one for the base, a disc with a hole in the middle and bottom surfaces rendered, and one for the top, another disc with a hole in the middle, and top surfaces rendered.

That can all be done pretty easily with a triangle strip array.