Fixes some sliders with too much control points.

src/itdelatrisu/opsu/objects/curves/Bezier2.java

@@ -77,8 +77,9 @@ public class Bezier2 {
 		Vec2f c = new Vec2f();
 		int n = points.length - 1;
 		for (int i = 0; i <= n; i++) {
-			c.x += points[i].x * bernstein(i, n, t);
-			c.y += points[i].y * bernstein(i, n, t);
+			double b = bernstein(i, n, t);
+			c.x += points[i].x * b;
+			c.y += points[i].y * b;
 		}
 		return c;
 	}
@@ -104,12 +105,21 @@ public class Bezier2 {
 	public float totalDistance() { return totalDistance; }
 	
 	/**
-	 * Calculates the factorial of a number.
+	 * http://en.wikipedia.org/wiki/Binomial_coefficient#Binomial_coefficient_in_programming_languages
+	 * 
 	 */
-	private static long factorial(int n) {
-		return (n <= 1 || n > 20) ? 1 : n * factorial(n - 1);
+	public static long binomialCoefficient(int n, int k) {
+		if (k < 0 || k > n)
+			return 0;
+		if (k == 0 || k == n)
+			return 1;
+		k = Math.min(k, n - k); // # take advantage of symmetry
+		long c = 1;
+		for (int i = 0; i < k; i++) {
+			c = c * (n - i) / (i + 1);
+		}
+		return c;
 	}
-
 	/**
 	 * Calculates the Bernstein polynomial.
 	 * @param i the index
@@ -117,7 +127,8 @@ public class Bezier2 {
 	 * @param t the t value [0, 1]
 	 */
 	private static double bernstein(int i, int n, float t) {
-		return factorial(n) / (factorial(i) * factorial(n - i)) *
-		       Math.pow(t, i) * Math.pow(1 - t, n - i);
+		return binomialCoefficient(n, i) * Math.pow(t, i) * Math.pow(1 - t, n - i);
 	}
+	
+
 }

src/itdelatrisu/opsu/objects/curves/Curve.java

@@ -87,13 +87,4 @@ public abstract class Curve {
 		return a * (1 - t) + b * t;
 	}
 
-	/**
-	 * A recursive method to evaluate polynomials in Bernstein form or Bezier curves.
-	 * http://en.wikipedia.org/wiki/De_Casteljau%27s_algorithm
-	 */
-	protected float deCasteljau(float[] a, int i, int order, float t) {
-		if (order == 0)
-			return a[i];
-		return lerp(deCasteljau(a, i, order - 1, t), deCasteljau(a, i + 1, order - 1, t), t);
-	}
 }