slider follow circle start/end animations (itdelatrisu/opsu@99c698b)

src/itdelatrisu/opsu/GameData.java

@@ -60,6 +60,8 @@ public class GameData {
 	/** Time, in milliseconds, for a hit circle to fade. */
 	public static final int HITCIRCLE_FADE_TIME = 300;
 
+	public static final int FOLLOWCIRCLE_FADE_TIME = HITCIRCLE_FADE_TIME / 2;
+
 	/** Duration, in milliseconds, of a combo pop effect. */
 	private static final int COMBO_POP_TIME = 250;
 
@@ -991,6 +993,17 @@ public class GameData {
 			return;
 		}
 
+		// slider follow circle
+		if (hitResult.expand && (
+			hitResult.hitResultType == HitObjectType.SLIDER_FIRST || hitResult.hitResultType == HitObjectType.SLIDER_LAST)) {
+			float progress = AnimationEquation.OUT_CUBIC.calc((float) Utils.clamp(trackPosition - hitResult.time, 0, FOLLOWCIRCLE_FADE_TIME) / FOLLOWCIRCLE_FADE_TIME);
+			float scale = 1f - 0.2f * progress;
+			float alpha = 1f - progress;
+			Image fc = GameImage.SLIDER_FOLLOWCIRCLE.getImage().getScaledCopy(scale);
+			fc.setAlpha(alpha);
+			fc.drawCentered(hitResult.x, hitResult.y);
+		}
+
 		// hit circles
 		float progress = AnimationEquation.OUT_CUBIC.calc(
 			(float) Utils.clamp(trackPosition - hitResult.time, 0, HITCIRCLE_FADE_TIME) / HITCIRCLE_FADE_TIME);

src/itdelatrisu/opsu/objects/Slider.java

@@ -33,7 +33,6 @@ import itdelatrisu.opsu.ui.Colors;
 import itdelatrisu.opsu.ui.animations.AnimationEquation;
 
 import org.newdawn.slick.Color;
-import org.newdawn.slick.GameContainer;
 import org.newdawn.slick.Graphics;
 import org.newdawn.slick.Image;
 import yugecin.opsudance.Dancer;
@@ -110,8 +109,12 @@ public class Slider extends GameObject {
 	/** The current tick time for the follow circle expanding animation. */
 	private int tickExpandTime = 0;
 
+	private int followExpandTime = 0;
+
 	/** The duration of the follow circle expanding animation on ticks. */
 	private static final int TICK_EXPAND_TIME = 200;
+	private static final int FOLLOW_EXPAND_TIME = 150;
+	private static final int FOLLOW_SHRINK_TIME = 100;
 
 	/** Container dimensions. */
 	private static int containerWidth, containerHeight;
@@ -366,9 +369,25 @@ public class Slider extends GameObject {
 			}
 
 			// follow circle
-			if (followCircleActive) {
+			if (followCircleActive || followExpandTime > 0) {
 				float followCircleScale = 1f + (tickExpandTime / (float) TICK_EXPAND_TIME) * 0.1f;
-				GameImage.SLIDER_FOLLOWCIRCLE.getImage().getScaledCopy(followCircleScale).drawCentered(c.x, c.y);
+				float followAlpha = 1f;
+				if (followCircleActive && followExpandTime < FOLLOW_EXPAND_TIME) {
+					followExpandTime += DisplayContainer.instance.renderDelta;
+					followCircleScale *= 0.5f;
+					float progress = AnimationEquation.OUT_QUAD.calc((float) followExpandTime / FOLLOW_EXPAND_TIME);
+					followCircleScale = followCircleScale + followCircleScale * progress;
+					followAlpha = progress;
+				} else if (!followCircleActive) {
+					followExpandTime -= DisplayContainer.instance.renderDelta;
+					if (followExpandTime > FOLLOW_SHRINK_TIME) {
+						followExpandTime = FOLLOW_SHRINK_TIME;
+					}
+					float progress = 1f - AnimationEquation.IN_QUAD.calc((float) followExpandTime / FOLLOW_EXPAND_TIME);
+					followCircleScale *= progress;
+					followAlpha = progress;
+				}
+				GameImage.SLIDER_FOLLOWCIRCLE.getImage().getScaledCopy(followCircleScale).setAlpha(followAlpha).drawCentered(c.x, c.y);
 
 				// "flashlight" mod: dim the screen
 				if (GameMod.FLASHLIGHT.isActive()) {
@@ -716,7 +735,10 @@ public class Slider extends GameObject {
 		double distance = Math.hypot(c.x - mouseX, c.y - mouseY);
 		if (((keyPressed || GameMod.RELAX.isActive()) && distance < followRadius) || isAutoMod) {
 			// mouse pressed and within follow circle
+			if (!followCircleActive) {
 				followCircleActive = true;
+				followExpandTime = 0;
+			}
 
 			// held during new repeat
 			if (isNewRepeat) {

src/org/newdawn/slick/Image.java

@@ -981,8 +981,9 @@ public class Image implements Renderable {
      * 
      * @param alpha The alpha value to use when rendering this image
      */
-    public void setAlpha(float alpha) {
+    public Image setAlpha(float alpha) {
     	this.alpha = alpha;
+        return this;
     }
     
     /**