public Vector2 ComputeRightTangent(Vector2[] d, int end)
/* d; Digitized points */
/* end; Index to "right" end of region */
{
Vector2 tHat2;
tHat2 = V2SubII(d[end - 1], d[end]);
// tHat2 = V2Normalize(tHat2);
tHat2.V2Normalize();
// System.out.println("IN RIGHT TANGENT:"+tHat2.xval()+" "+tHat2.yval() );
return tHat2;
}
/*
* ComputeLeftTangent, ComputeRightTangent, ComputeCenterTangent :
*Approximate unit tangents at endpoints and "center" of digitized curve
*/
public Vector2 ComputeLeftTangent(Vector2[] d, int end)
/* d; Digitized points*/
/* end; Index to "left" end of region */
{
Vector2 tHat1;
tHat1 = V2SubII(d[end + 1], d[end]);
// tHat1 = V2Normalize(tHat1);
// System.out.println("end "+end+" d[end+1] "+d[end+1].xval()+" "+d[end+1].yval()+" d[end]
// "+d[end].xval()+" "+d[end].yval()+" IN LEFT TANGENT:"+tHat1.xval()+" "+tHat1.yval() );
tHat1.V2Normalize();
// System.out.println("IN LEFT TANGENT:"+tHat1.xval()+" "+tHat1.yval() );
return tHat1;
}
public Vector2 ComputeCenterTangent(Vector2[] d, int center)
/* d; Digitized points */
/*center; Index to point inside region */
{
Vector2 V1, V2, tHatCenter;
V1 = V2SubII(d[center - 1], d[center]);
V2 = V2SubII(d[center], d[center + 1]);
tHatCenter = new Vector2();
tHatCenter.xset((V1.xval() + V2.xval()) / 2.0);
tHatCenter.yset((V1.yval() + V2.yval()) / 2.0);
tHatCenter.V2Normalize();
return tHatCenter;
}