import com.sun.j3d.utils.geometry.*;
import javax.media.j3d.*;
import javax.vecmath.*;

public class Arrow extends Applet
{
  //Creates an 3Darrow between point stPt and endPt
  public static 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;
  }
}