Add BezierCurve:getSegment(t1, t2)

Returns a BezierCurve that corresponds to the curve-segment between t1 and t2
on the original curve.

src/modules/math/BezierCurve.h

@@ -113,6 +113,15 @@ public:
 	 **/
 	Vector evaluate(double t) const;
 
+	/**
+	 * Get curve segment starting at t1 and ending at t2.
+	 * The new curve will be parametrized from 0 <= t <= 1.
+	 * @param t1 Start of the segment.
+	 * @param t2 End of the segment.
+	 * @returns Bezier curve covering the segment.
+	 */
+	BezierCurve* getSegment(double t1, double t2) const;
+
 	/**
 	 * Renders the curve by subdivision.
 	 * @param accuracy The 'fineness' of the curve.