Added star fountains to main menu.

- Added MusicController methods to get measure progress (similar to beat progress).
- Workaround for inaccurate track positions after looping by not looping.
- Make sure star duration is positive.

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

src/itdelatrisu/opsu/ui/StarFountain.java

@@ -0,0 +1,85 @@
+package itdelatrisu.opsu.ui;
+
+import itdelatrisu.opsu.GameImage;
+import itdelatrisu.opsu.ui.animations.AnimatedValue;
+import itdelatrisu.opsu.ui.animations.AnimationEquation;
+
+import org.newdawn.slick.Image;
+
+/**
+ * Star fountain consisting of two star streams.
+ */
+public class StarFountain {
+	/** The (approximate) number of stars in each burst. */
+	private static final int BURST_SIZE = 80;
+
+	/** Star streams. */
+	private final StarStream left, right;
+
+	/** Burst progress. */
+	private final AnimatedValue burstProgress = new AnimatedValue(800, 0, 1, AnimationEquation.LINEAR);
+
+	/**
+	 * Initializes the star fountain.
+	 * @param containerWidth the container width
+	 * @param containerHeight the container height
+	 */
+	public StarFountain(int containerWidth, int containerHeight) {
+		Image img = GameImage.STAR2.getImage();
+		float xDir = containerWidth * 0.4f, yDir = containerHeight * 0.75f;
+		this.left = new StarStream(-img.getWidth(), containerHeight, xDir, -yDir, 0);
+		this.right = new StarStream(containerWidth, containerHeight, -xDir, -yDir, 0);
+		setStreamProperties(left);
+		setStreamProperties(right);
+	}
+
+	/**
+	 * Sets attributes for the given star stream.
+	 */
+	private void setStreamProperties(StarStream stream) {
+		stream.setDirectionSpread(60f);
+		stream.setDurationSpread(1100, 200);
+	}
+
+	/**
+	 * Draws the star fountain.
+	 */
+	public void draw() {
+		left.draw();
+		right.draw();
+	}
+
+	/**
+	 * Updates the stars in the fountain by a delta interval.
+	 * @param delta the delta interval since the last call
+	 */
+	public void update(int delta) {
+		left.update(delta);
+		right.update(delta);
+		if (burstProgress.update(delta)) {
+			int size = Math.round((float) delta / burstProgress.getDuration() * BURST_SIZE);
+			left.burst(size);
+			right.burst(size);
+		}
+	}
+
+	/**
+	 * Creates a burst of stars to be processed during the next {@link #update(int)} call.
+	 * @param wait if {@code true}, will not burst if a previous burst is in progress
+	 */
+	public void burst(boolean wait) {
+		if (wait && (burstProgress.getTime() < burstProgress.getDuration() || !left.isEmpty() || !right.isEmpty()))
+			return;
+
+		burstProgress.setTime(0);
+	}
+
+	/**
+	 * Clears the stars currently in the fountain.
+	 */
+	public void clear() {
+		left.clear();
+		right.clear();
+		burstProgress.setTime(burstProgress.getDuration());
+	}
+}

src/itdelatrisu/opsu/ui/StarStream.java

@@ -32,7 +32,7 @@ import java.util.Random;
 import org.newdawn.slick.Image;
 
 /**
- * Horizontal star stream.
+ * Star stream.
  */
 public class StarStream {
 	/** The origin of the star stream. */
@@ -196,7 +196,7 @@ public class StarStream {
 		Vec2f offset = position.cpy().add(direction.cpy().nor().normalize().scale((float) getGaussian(0, positionSpread)));
 		Vec2f dir = direction.cpy().scale(distanceRatio).add((float) getGaussian(0, directionSpread), (float) getGaussian(0, directionSpread));
 		int angle = (int) getGaussian(0, 22.5);
-		int duration = (int) (distanceRatio * getGaussian(durationBase, durationSpread));
+		int duration = Math.max(0, (int) (distanceRatio * getGaussian(durationBase, durationSpread)));
 		AnimationEquation eqn = random.nextBoolean() ? AnimationEquation.IN_OUT_QUAD : AnimationEquation.OUT_QUAD;
 
 		return new Star(offset, dir, angle, duration, eqn);
@@ -216,6 +216,11 @@ public class StarStream {
 	 */
 	public void clear() { stars.clear(); }
 
+	/**
+	 * Returns whether there are any stars currently in this stream.
+	 */
+	public boolean isEmpty() { return stars.isEmpty(); }
+
 	/**
 	 * Returns the next pseudorandom, Gaussian ("normally") distributed {@code double} value
 	 * with the given mean and standard deviation.