Re: [JAVA3D] Arrow Geometry Needed

[S P Nath]

Hi Javier,
Here I am attaching a sample file that draws arrows.
the arrow class has a function that will return a "TransformGroup" node
having the arrow below it.
This is a 3D arrow and made up of two cones and a cylinder.
The input parameters are arrow diameter, start point and end point.

(Note: if you are populating large number of arrows in the scene, you
better opt for a different way to represent the same. So that you can
instanciate the same object in the scene)
Cheers
Nath
______________________________________________________________________________


On Tue, 9 May 2000, [iso-8859-1] S�nchez Sanz, Javier wrote:

> Hi, I need a geometry of an arrow (ej: ->). Does anyone code or a library of
> any kind of arrows?
> Thanks in advance.
> Javi
> 
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import java.applet.Applet;
import java.awt.Frame;
import java.awt.event.*;
import  com.sun.j3d.utils.applet.MainFrame;
import java.awt.BorderLayout;
import com.sun.j3d.utils.universe.*;
import com.sun.j3d.utils.geometry.*;
import javax.media.j3d.*;
import javax.vecmath.*;

public class arrow extends Applet
{
  public static void main(String[] args)
  {
    Applet scene = new arrow();
    Frame jFrame = new MainFrame(scene, 500, 500);
  }

  //Constructor for the applet
  public arrow()
  {
    setLayout(new BorderLayout());
    Canvas3D jCanvas3D = new Canvas3D(null);
    add("Center", jCanvas3D);
    BranchGroup jScene = createSceneGraph();
    jScene.compile();
    SimpleUniverse jVirtualUniverse = new SimpleUniverse(jCanvas3D);
    jVirtualUniverse.getViewingPlatform().setNominalViewingTransform();
    jVirtualUniverse.addBranchGraph(jScene);
  }

  //Creates an 3Darrow between point stPt and endPt
  public TransformGroup createArrow(float ArrowDia, Vector3f stPt, Vector3f endPt)
  {
    float arrowDir = ((endPt.y-stPt.y)/Math.abs(endPt.y-stPt.y));
    double lenSq =  (stPt.x-endPt.x)*(stPt.x-endPt.x) +
                    (stPt.y-endPt.y)*(stPt.y-endPt.y) +
                    (stPt.z-endPt.z)*(stPt.z-endPt.z);
    float ArrowLen = (float) Math.sqrt(lenSq);
    float ArrowHeadLen = 5.0f*ArrowDia;
    float ArrowHeadDia = 2.0f*ArrowDia;
    float ArrowTailDia = ArrowDia;
    float AroowTailLen = 2.5f*ArrowDia;
    float CylenderLen = ArrowLen - ArrowHeadLen - AroowTailLen;

    //Rotation Matrix for whole arrow (cylinder + two cones)
    Matrix4f RotMat = new Matrix4f();
    float CosTheta = (endPt.x - stPt.x)/ArrowLen;
    float SinTheta = (endPt.y - stPt.y)/ArrowLen;

    System.out.println("Value of Cos");
    System.out.print(CosTheta);
    System.out.println("Value of Sin");
    System.out.print(SinTheta);

    RotMat.m00 = SinTheta;
    RotMat.m01 = CosTheta;
    RotMat.m02 = 0.0f;
    RotMat.m03 = stPt.x + (endPt.x - stPt.x)/2.0f - 
arrowDir*(ArrowHeadLen-AroowTailLen)/2.0f;

    RotMat.m10 = -CosTheta;
    RotMat.m11 = SinTheta;
    RotMat.m12 = 0.0f;
    RotMat.m13 = stPt.y + (endPt.y - stPt.y)/2.0f - 
arrowDir*(ArrowHeadLen-AroowTailLen)/2.0f;

    RotMat.m20 = 0.0f;
    RotMat.m21 = 0.0f;
    RotMat.m22 = 1.0f;
    RotMat.m23 = stPt.z + (endPt.z - stPt.z)/2.0f - 
arrowDir*(ArrowHeadLen-AroowTailLen)/2.0f;

    RotMat.m30 = 0.0f;
    RotMat.m31 = 0.0f;
    RotMat.m32 = 0.0f;
    RotMat.m33 = 1.0f;


    //Apperance for the arrow
    Appearance caAppearance = new Appearance();
    ColoringAttributes caColor;
    caColor = new ColoringAttributes();
    caColor.setColor(0.8f,0.8f,0.8f);
    caAppearance.setColoringAttributes(caColor);

    Transform3D caTransform = new Transform3D();
    caTransform.set(RotMat);
    TransformGroup caTransformGroup = new TransformGroup(caTransform);

    Node cArrowCylinder = new Cylinder(ArrowDia, CylenderLen, caAppearance);

    Transform3D arrowHeadTransform = new Transform3D();
    arrowHeadTransform.set(new 
Vector3f(0.0f,CylenderLen/2.0f+0.5f*ArrowHeadLen,0.0f));
    TransformGroup arrowHeadTransformGroup = new TransformGroup(arrowHeadTransform);

    Transform3D arrowTailTransform = new Transform3D();
    arrowTailTransform.set(new 
Vector3f(0.0f,-CylenderLen/2.0f-0.5f*AroowTailLen,0.0f));
    Transform3D arrowTailTransformTmp = new Transform3D();
    arrowTailTransformTmp.rotZ(Math.PI);
    arrowTailTransform.mul(arrowTailTransformTmp);
    TransformGroup arrowTailTransformGroup = new TransformGroup(arrowTailTransform);

    Node ArrowHeadCone = new Cone(ArrowHeadDia, ArrowHeadLen, 1, caAppearance);
    Node ArrowTailCone = new Cone(ArrowTailDia, AroowTailLen, 1, caAppearance);
    arrowHeadTransformGroup.addChild(ArrowHeadCone);
    arrowTailTransformGroup.addChild(ArrowTailCone);

    caTransformGroup.addChild(arrowHeadTransformGroup);
    caTransformGroup.addChild(arrowTailTransformGroup);
    caTransformGroup.addChild(cArrowCylinder);

    return caTransformGroup;
  }


  public BranchGroup createSceneGraph()
  {
    BranchGroup SceneRoot = new BranchGroup();

    float PCylnRadius = 0.05f;
    SceneRoot.addChild(createArrow(0.02f, new Vector3f(-0.2f,-0.25f,0.0f), new 
Vector3f(-0.6f,0.25f,0.0f)));
    SceneRoot.addChild(createArrow(0.02f, new Vector3f(0.5f,-0.25f,0.0f), new 
Vector3f(0.6f,0.25f,0.0f)));
    SceneRoot.addChild(createArrow(0.02f, new Vector3f(0.0f,0.25f,0.0f), new 
Vector3f(0.0f,-0.25f,0.0f)));
    SceneRoot.addChild(createArrow(0.02f, new Vector3f(0.35f,0.25f,0.0f), new 
Vector3f(0.35f,-0.25f,0.0f)));

    return SceneRoot;
  }

}