package cse1030.drawing;

/**
 * A horizontal shear transformation. A shear transformation transforms
 * a rectangle into a parallelogram. The amount of shear is controlled
 * by a scalar parameter called the shear factor.
 * 
 * @author CSE1030Z
 *
 */
public class Shear extends Transformation {

  private double h;
  
  /**
   * Create a shear transformation given a name and the shear factor
   * <code>h</code>.
   * 
   * @param name the name of the transformation
   * @param h the shear factor
   */
  public Shear(String name, double h) {
    super(name);
    this.h = h;  
  }


  /**
   * Transform a point changing its coordinates. For a shear of
   * of factor <code>h</code> the <code>x</code> and <code>y</code>
   * coordinates of the point are transformed as follows:
   * 
   * <p>
   * <code>x = x + h * y</code><br />
   * <code>y = y</code> (i.e., the y coordinate is unchanged)<br />
   * 
   * @see cse1030.drawing.Transformation#transform(cse1030.drawing.Point2D)
   *
   * @param p the point to transform
   */
  @Override
  public void transform(Point2D p) {
    p.setX(p.getX() + this.h * p.getY());
  }

  
  /**
   * Apply the shear to a point to produce a new point leaving the
   * original point unchanged.
   * 
   * @see cse1030.drawing.Shear#transform(cse1030.drawing.Point2D)
   * 
   * @see cse1030.drawing.Transformation#apply(cse1030.drawing.Point2D)
   *
   * @param p the point to apply the transformation to
   * @return a new point equal to shearing the input point <code>p</code>
   */
  @Override
  public Point2D apply(Point2D p) {
    Point2D q = new Point2D(p);
    this.transform(q);
    return q;
  }
  
  /**
   * Get a string representation of the shear. The returned string is the
   * name of the shear followed by the string <code>" : shear of factor "</code>
   * followed by the shear factor. For example, a shear of factor <code>1.876435632</code> named
   * <code>T1</code> has the following string representation:
   * 
   * <p>
   * <code>"T1 : shear of factor 1.876435632"</code>
   * 
   * @see cse1030.drawing.Transformation#toString()
   * 
   * @return the string representation of the shear
   */
  @Override
  public String toString() {
    return super.toString() + " : shear of factor " + this.h;
  }
  
}