package org.newdawn.slick.geom;
/**
* A beizer curve implementation. The curve is defined by a start point, an end point
* and two control points that it will tend towards. This is implementation is fixed
* segmenting meaning it doesn't scale too well.
*
* @author kevin
*/
public class Curve extends Shape {
/** The start point of the curve */
private Vector2f p1;
/** The first control point */
private Vector2f c1;
/** The second control point */
private Vector2f c2;
/** The end point of the curve */
private Vector2f p2;
/** The number of lines segments the curve is built out of */
private int segments;
/**
* Create a new curve with the default segments (20)
*
* @param p1 The start of the curve
* @param c1 The first control point
* @param c2 The second control point
* @param p2 The end of the curve
*/
public Curve(Vector2f p1, Vector2f c1, Vector2f c2, Vector2f p2) {
this(p1,c1,c2,p2,20);
}
/**
* Create a new curve
*
* @param p1 The start of the curve
* @param c1 The first control point
* @param c2 The second control point
* @param p2 The end of the curve
* @param segments The number of segments to use
*/
public Curve(Vector2f p1, Vector2f c1, Vector2f c2, Vector2f p2, int segments) {
this.p1 = new Vector2f(p1);
this.c1 = new Vector2f(c1);
this.c2 = new Vector2f(c2);
this.p2 = new Vector2f(p2);
this.segments = segments;
pointsDirty = true;
}
/**
* Get the point at a particular location on the curve
*
* @param t A value between 0 and 1 defining the location of the curve the point is at
* @return The point on the curve
*/
public Vector2f pointAt(float t) {
float a = 1 - t;
float b = t;
float f1 = a * a * a;
float f2 = 3 * a * a * b;
float f3 = 3 * a * b * b;
float f4 = b * b * b;
float nx = (p1.x * f1) + (c1.x * f2) + (c2.x * f3) + (p2.x * f4);
float ny = (p1.y * f1) + (c1.y * f2) + (c2.y * f3) + (p2.y * f4);
return new Vector2f(nx,ny);
}
/**
* @see org.newdawn.slick.geom.Shape#createPoints()
*/
protected void createPoints() {
float step = 1.0f / segments;
points = new float[(segments+1) * 2];
for (int i=0;i<segments+1;i++) {
float t = i * step;
Vector2f p = pointAt(t);
points[i*2] = p.x;
points[(i*2)+1] = p.y;
}
}
/**
* @see org.newdawn.slick.geom.Shape#transform(org.newdawn.slick.geom.Transform)
*/
public Shape transform(Transform transform) {
float[] pts = new float[8];
float[] dest = new float[8];
pts[0] = p1.x; pts[1] = p1.y;
pts[2] = c1.x; pts[3] = c1.y;
pts[4] = c2.x; pts[5] = c2.y;
pts[6] = p2.x; pts[7] = p2.y;
transform.transform(pts, 0, dest, 0, 4);
return new Curve(new Vector2f(dest[0],dest[1]), new Vector2f(dest[2],dest[3]),
new Vector2f(dest[4],dest[5]), new Vector2f(dest[6],dest[7]));
}
/**
* True if this is a closed shape
*
* @return True if this is a closed shape
*/
public boolean closed() {
return false;
}
}