public static Point Project2Vector(Point pt1, Point pt2, Point pt3)
{
// project a vector v1 formed by pt1-pt3 into another vector v2 formed by pt1-pt2
Point v1 = PA.Subtract(pt3, pt1);
Point v2 = PA.Subtract(pt2, pt1);
float scale = (float)(PA.Dot(v1, v2) / PA.Norm(v2) / PA.Norm(v2));
PointF projected_pt3 = PA.Add(PA.Multiply(PA.Int2Float(v2), scale), pt1);
return(PA.Float2Int(projected_pt3));
}
public static Point Project2NormalVector(Point pt1, Point pt2, Point pt3)
{
/* project a vector v1 formed by pt1-pt3 into the direction of
* the normal vector of another vector v2 formed by pt1-pt2 */
// compute the unit normal vector of vector v2
Point v2 = PA.Subtract(pt2, pt1);
float magnitude = (float)(PA.Norm(pt1, pt2));
PointF unit_normal = new PointF(v2.Y / magnitude, -v2.X / magnitude);
// project v1 into the normal vector
Point v1 = PA.Subtract(pt3, pt1);
PointF projected = PA.Multiply(unit_normal, (float)PA.Dot(v1, unit_normal));
PointF projected_v3 = PA.Add(projected, pt1);
return(PA.Float2Int(projected_v3));
}