如何在Java 3D中旋转对象？ [英] How to rotate an object in Java 3D?

问题描述

 锥体=新锥体（2f，3f） ）; 
 
 Transform3D t3d = new Transform3D（）; 
 TransformGroup coneTransform = new TransformGroup（t3d）; 
 coneTransform.setCapability（TransformGroup.ALLOW_TRANSFORM_WRITE）; 
 
 t3d.setTranslation（new Vector3f（0f，0f，0f）; 
 coneTransform.setTransform（t3d）; 
 coneTransform.addChild（cone）; 
 
 this.addChild（coneTransform）; 
  

假设我坐在点（1,1 ，1），我想让锥体的尖端指向一条穿过（0,0,0）和（1,1,1）的假想线...我怎么能做到这一点？

下面是我一直在尝试的一个例子：

  Transform3D t3d = new Transform3D（） ; 
 
 Vector3f direction = new Vector3f（1,2,1）; 
 
 final double angleX = direction.angle（new Vector3f（1,0,0））; 
 final double angleY = direction.angle（new Vector3f（0,1,0））; 
 final double angleZ = direction.angle（new Vector3f（0,0,1））; 
 
 t3d.rotX（angleX）; 
 t3d.rotY（angleY）; 
 t3d.rotZ（angleZ）; 
 
 t3d.setTranslation（direction）; 
 
 coneTransform.setTransform（t3d）; 
  

在此先感谢您的帮助！ p>

我最终通过使用Quaternion（我在这里了解到）了解了我想要做的事情： http://www.cs.uic.edu/~jbell/Courses/Eng591_F1999/outline_2.html 这是我的解决方案。

创建锥体：

  private void attachCone（float size） {
圆锥体=新圆锥体（大小，大小* 2）; 
 
 //旋转组
 arrowheadRotationGroup = new TransformGroup（）; 
 arrowheadRotationGroup。 
 setCapability（TransformGroup.ALLOW_TRANSFORM_WRITE）; 
 arrowheadRotationGroup.addChild（cone）; 
 
 //用于定位锥体的组
 arrowheadPositionGroup = new TransformGroup（）; 
 arrowheadPositionGroup。 
 setCapability（TransformGroup.ALLOW_TRANSFORM_WRITE）; 
 arrowheadPositionGroup.addChild（arrowheadRotationGroup）; 
 
 super.addChild（arrowheadPositionGroup）; 
} 
  

现在，当我想旋转锥体指向特定的方向作为从点（0,0,0）到（direction.x，direction.y，direction.z）的向量，我使用：

  private final Vector3f yAxis = new Vector3f（0f，1f，0f）; 
私有Vector3f方向; 
 
 private void rotateCone（）{
 //获取垂直于方向的标准化轴
 Vector3f axis = new Vector3f（）; 
 axis.cross（yAxis，direction）; 
 axis.normalize（）; 
 
 //当想要的方向是yAxis上的一个点时，如果（float.isNaN（axis.x）&& Float.isNaN（axis.y））在x 
上旋转， && Float.isNaN（axis.z））
 {
 axis.x = 1f; 
 axis.y = 0f; 
 axis.z = 0f; 
} 
 //计算四元数变换
 final float angleX = yAxis.angle（direction）; 
 final float a = axis.x *（float）Math.sin（angleX / 2f）; 
 final float b = axis.y *（float）Math.sin（angleX / 2f）; 
 final float c = axis.z *（float）Math.sin（angleX / 2f）; 
 final float d =（float）Math.cos（angleX / 2f）; 
 
 Transform3D t3d = new Transform3D（）; 
 Quat4f quat =新的Quat4f（a，b，c，d）; 
 t3d.set（quat）; 
 arrowheadRotationGroup.setTransform（t3d）; 
 
 Transform3D translateToTarget = new Transform3D（）; 
 translateToTarget.setTranslation（this.direction）; 
 arrowheadPositionGroup.setTransform（translateToTarget）; 
} 
  

I have a Cone I drew in Java 3D with the following code:

Cone cone = new Cone(2f, 3f);

Transform3D t3d = new Transform3D();
TransformGroup coneTransform = new TransformGroup(t3d);
coneTransform.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);

t3d.setTranslation(new Vector3f(0f,0f,0f);
coneTransform.setTransform(t3d);
coneTransform.addChild(cone);

this.addChild(coneTransform);

Suppose I have the cone sitting at point (1,1,1) and I want the tip of the cone to point down an imaginary line running through (0,0,0) and (1,1,1)... how can I do this?

Here's an example of what I've been trying:

Transform3D t3d = new Transform3D();  

Vector3f direction = new Vector3f(1,2,1);    

final double angleX = direction.angle(new Vector3f(1,0,0));
final double angleY = direction.angle(new Vector3f(0,1,0));
final double angleZ = direction.angle(new Vector3f(0,0,1));

t3d.rotX(angleX);
t3d.rotY(angleY);
t3d.rotZ(angleZ);

t3d.setTranslation(direction);

coneTransform.setTransform(t3d);

Thanks in advance for all help!

解决方案

I finally figured out what I wanted to do by using Quaternions, which I learned about here: http://www.cs.uic.edu/~jbell/Courses/Eng591_F1999/outline_2.html Here's my solution.

Creating the cone:

 private void attachCone(float size) {
        Cone cone = new Cone(size, size* 2);

        // The group for rotation
        arrowheadRotationGroup = new TransformGroup();
        arrowheadRotationGroup.
             setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);
        arrowheadRotationGroup.addChild(cone);

        // The group for positioning the cone
        arrowheadPositionGroup = new TransformGroup();
        arrowheadPositionGroup. 
              setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);
        arrowheadPositionGroup.addChild(arrowheadRotationGroup);

        super.addChild(arrowheadPositionGroup);
    }

Now, when I want to rotate the cone to point in a certain direction specified as the vector from the point (0,0,0) to (direction.x, direction.y, direction.z), I use:

private final Vector3f yAxis = new Vector3f(0f, 1f, 0f);
private Vector3f direction; 

private void rotateCone() {
        // Get the normalized axis perpendicular to the direction 
        Vector3f axis = new Vector3f();
        axis.cross(yAxis, direction);
        axis.normalize();

        // When the intended direction is a point on the yAxis, rotate on x
        if (Float.isNaN(axis.x) && Float.isNaN(axis.y) && Float.isNaN(axis.z)) 
        {
            axis.x = 1f;
            axis.y = 0f;
            axis.z = 0f;
        }
        // Compute the quaternion transformations
        final float angleX = yAxis.angle(direction);
        final float a = axis.x * (float) Math.sin(angleX / 2f);
        final float b = axis.y * (float) Math.sin(angleX / 2f);
        final float c = axis.z * (float) Math.sin(angleX / 2f);
        final float d = (float) Math.cos(angleX / 2f);

        Transform3D t3d = new Transform3D();
        Quat4f quat = new Quat4f(a, b, c, d);
        t3d.set(quat);
        arrowheadRotationGroup.setTransform(t3d);

        Transform3D translateToTarget = new Transform3D();
        translateToTarget.setTranslation(this.direction);
        arrowheadPositionGroup.setTransform(translateToTarget);
    }

这篇关于如何在Java 3D中旋转对象？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！