Code style cleanup from #12.

- Moved all curve-related classes into a new package.
- Added some fields and methods to Curve abstract class.
- Removed the old (no longer used) Bezier subclass.
- Changed Error throwing to ErrorHandler.error() calls.
- Formatted code.

Also fixed a crash when reaching the ranking screen with the "Auto" mod active.

Signed-off-by: Jeffrey Han <itdelatrisu@gmail.com>

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

@@ -0,0 +1,97 @@
+/*
+ * opsu! - an open-source osu! client
+ * Copyright (C) 2014, 2015 Jeffrey Han
+ *
+ * opsu! is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * opsu! is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with opsu!.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package itdelatrisu.opsu.objects.curves;
+
+import itdelatrisu.opsu.OsuHitObject;
+
+import org.newdawn.slick.Color;
+
+/**
+ * Representation of a curve.
+ */
+public abstract class Curve {
+	/** The associated OsuHitObject. */
+	protected OsuHitObject hitObject;
+
+	/** The color of this curve. */
+	protected Color color;
+
+	/**
+	 * Constructor.
+	 * @param hitObject the associated OsuHitObject
+	 * @param color the color of this curve
+	 */
+	protected Curve(OsuHitObject hitObject, Color color) {
+		this.hitObject = hitObject;
+		this.color = color;
+	}
+
+	/**
+	 * Returns the point on the curve at a value t.
+	 * @param t the t value [0, 1]
+	 * @return the point [x, y]
+	 */
+	public abstract float[] pointAt(float t);
+
+	/**
+	 * Draws the full curve to the graphics context.
+	 */
+	public abstract void draw();
+
+	/**
+	 * Returns the angle of the first control point.
+	 */
+	public abstract float getEndAngle();
+
+	/**
+	 * Returns the angle of the last control point.
+	 */
+	public abstract float getStartAngle();
+
+	/**
+	 * Returns the x coordinate of the control point at index i.
+	 */
+	protected float getX(int i) {
+		return (i == 0) ? hitObject.getX() : hitObject.getSliderX()[i - 1];
+	}
+
+	/**
+	 * Returns the y coordinate of the control point at index i.
+	 */
+	protected float getY(int i) {
+		return (i == 0) ? hitObject.getY() : hitObject.getSliderY()[i - 1];
+	}
+
+	/**
+	 * Linear interpolation of a and b at t.
+	 */
+	protected float lerp(float a, float b, float t) {
+		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);
+	}
+}