如何根据鼠标单击获取 3D 中点的坐标？

Question

我希望当我单击屏幕上的特定点时，函数调用会返回我单击的 3d 场景中的点。

例如，当我点击屏幕左上角时，它应该返回 x = 0, y = 1, z= 1;请帮助我创建一个方法来执行此操作。

编辑：

Root = new BranchGroup();

setLayout(new BorderLayout());
add(canvas3D,BorderLayout.CENTER);
SimpleUniverse universe = new SimpleUniverse(canvas3D);

Shape();
universe.addBranchGraph(Root);
ViewingPlatform viewingPlatform = universe.getViewingPlatform();
OrbitBehavior behavior = new OrbitBehavior(canvas3D);
behavior.setSchedulingBounds(bounds);
viewingPlatform.setViewPlatformBehavior(behavior);
viewingPlatform.setNominalViewingTransform();
}

我在 NetBeans 中使用 SimpleUniverse。

Answer 1

恐怕答案并不直接。根据场景中的内容，单击屏幕时鼠标坐标应该发生变化。例如，如果您有两个对象，因此前面的对象遮挡了后面的对象，那么您需要获取前面的对象坐标。这称为“鼠标选取”，有多种技术可以实现。我找到了一些论坛来解释它是如何完成的并有代码示例。

基本上，这个想法是您想象在您（用户）和屏幕之间存在激光（或其他投射射线的东西）。然后，这个东西会通过屏幕表面上鼠标单击的点“进入”屏幕来投射一条光线。然后，光线路径上的任何物体都将被拾取，并且可以选择解析光线路径中对象的遮挡顺序，为您提供最接近“屏幕”的对象。

我对 J3D 不熟悉，但从一些教程中将以下代码拼凑在一起。它至少应该让你开始。您要查找的内容是底部的这一行 Point3D Intercept = ... 。

http://www.java3d.org/selection.html

package j3d_picking;

import java.awt.*;
import javax.swing.*;
import javax.media.j3d.*;
import com.sun.j3d.utils.universe.*;
import com.sun.j3d.utils.picking.behaviors.*;
import com.sun.j3d.utils.geometry.*;
import com.sun.j3d.utils.picking.PickIntersection;
import com.sun.j3d.utils.picking.PickResult;
import com.sun.j3d.utils.picking.PickTool;
import javax.vecmath.Point3d;

public class HelloJava3D
        extends JFrame
{

    public HelloJava3D()
    {
        GraphicsConfiguration config = SimpleUniverse.getPreferredConfiguration();
        Canvas3D canvas3D = new Canvas3D(config);

        BranchGroup scene = createSceneGraph();

        // SimpleUniverse is a Convenience Utility class
        SimpleUniverse simpleU = new SimpleUniverse(canvas3D);

        // This moves the ViewPlatform back a bit so the
        // objects in the scene can be viewed.
        simpleU.getViewingPlatform().setNominalViewingTransform();

        BoundingSphere behaveBounds = new BoundingSphere();
        ExamplePickBehavior behavior = new ExamplePickBehavior(canvas3D, scene, behaveBounds);
        scene.addChild(behavior);

        scene.compile();
        simpleU.addBranchGraph(scene);

        getContentPane().add(canvas3D, BorderLayout.CENTER);
    } // end of HelloJava3D (constructor)

    public BranchGroup createSceneGraph()
    {
        // Create the root of the branch graph
        BranchGroup objRoot = new BranchGroup();

        // Create a simple shape leaf node, add it to the scene graph.
        // ColorCube is a Convenience Utility class
        ColorCube cube = new ColorCube(0.4);
        cube.setCapability(Node.ENABLE_PICK_REPORTING);
        PickTool.setCapabilities(cube, PickTool.INTERSECT_FULL);
        objRoot.addChild(cube);

        return objRoot;
    } // end of createSceneGraph method of HelloJava3D

    public static void main(String[] args)
    {
        JFrame frame = new HelloJava3D();
        frame.setTitle("Hello Java3D");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setBounds(0, 0, 400, 300);
        frame.setVisible(true);
    }

    private class ExamplePickBehavior extends PickMouseBehavior
    {

        public ExamplePickBehavior(Canvas3D canvas, BranchGroup bg, Bounds bounds)
        {
            super(canvas, bg, bounds);
            setSchedulingBounds(bounds);

            pickCanvas.setMode(PickTool.GEOMETRY_INTERSECT_INFO);
            // allows PickIntersection objects to be returned
        }

        public void updateScene(int xpos, int ypos)
        {
            pickCanvas.setShapeLocation(xpos, ypos);
            // register mouse pointer location on the screen (canvas)

            Point3d eyePos = pickCanvas.getStartPosition();
            // get the viewer's eye location

            PickResult pickResult = null;
            pickResult = pickCanvas.pickClosest();
            // get the intersected shape closest to the viewer

            if (pickResult != null) {
                PickIntersection pi = pickResult.getClosestIntersection(eyePos);
                // get the closest intersect to the eyePos point
                Point3d intercept = pi.getPointCoordinatesVW();
                System.out.println(intercept);
                // extract the intersection pt in scene coords space
                // use the intersection pt in some way...
            }
        } // end of updateScene(  )
    } // end of ExamplePickBehavior class
}

Answer 2

在此处输入代码下面的 Java 代码，在 3D 屏幕中打印 3D 对象（形状）的中心坐标。结果是 (x=-0.5 ,y=0.0 ,z=0.4)

         public class secim2 extends MouseAdapter{


private PickCanvas pickCanvas;





public secim2(){
    JFrame pencere=new JFrame();
    pencere.setSize(300, 300);
    pencere.setVisible(true);
    JFrame frame = new JFrame(" 3D Box Select");

    GraphicsConfiguration config =                 SimpleUniverse.getPreferredConfiguration();

    Canvas3D canvas = new Canvas3D(config);

    SimpleUniverse universe = new SimpleUniverse(canvas);

    BranchGroup group = new BranchGroup();


    // create a color cube


       Transform3D transform= new Transform3D();
    Vector3d vector = new Vector3d(-0.5, 0.0, 0.4);

        Transform3D transform = new Transform3D();

        transform.setTranslation(vector);

        TransformGroup transformGroup = new TransformGroup(transform);

        ColorCube cube = new ColorCube(0.1f);

        transformGroup.addChild(cube);

        group.addChild(transformGroup);


        universe.getViewingPlatform().setNominalViewingTransform();

        universe.addBranchGraph(group);


      pickCanvas = new PickCanvas(canvas, group);

      pickCanvas.setMode(PickCanvas.GEOMETRY_INTERSECT_INFO);

     pencere.add(canvas);

      canvas.addMouseListener(this);


}

public void mouseClicked(MouseEvent e)

{



    pickCanvas.setShapeLocation(e);

    PickResult result = pickCanvas.pickClosest();

    if (result == null) {


    } else {

       Primitive p = (Primitive)result.getNode(PickResult.PRIMITIVE);  

       Shape3D s = (Shape3D)result.getNode(PickResult.SHAPE3D);

       if (p != null) {

         System.out.println(p.getClass().getName());


       } else if (s != null) {

             System.out.println(s.getClass().getName());

             Vector3f position = new Vector3f(); 

      s.getLocalToVworld(transform);  

        transform.get(position);

       System.out.print(position);

      // System.out.print( s.getLocalToVworld(transform2);
       } else{

          System.out.println("null");

       }

    }

}

}

public class tuval1 {

public static void main(String[] args) {
    // TODO Auto-generated method stub

new secim2();

}

}