first successful tween

com/danitheskunk/skunkworks/BaseGame.java

@@ -31,6 +31,7 @@ public abstract class BaseGame {
 			lastTime = currentTime;
 			window.tick();
 			//todo: frame rate control
+			rootNode.tick();
 			update(1000.0 / 60.0);
 			var rc = window.renderStart();
 			renderPre(rc);

com/danitheskunk/skunkworks/TestNode.java

@@ -11,9 +11,11 @@ public class TestNode extends BaseGame {
 		sprite.setTexture(window.loadTexture("demoassets/test.png"));
 		sprite.setPos(new Vec2f(100, 100));
 		rootNode.add(sprite);
+		sprite.tweenPos(new Vec2f(800, 400), 120).delay(600);
 	}
 
 	public static void main(String[] args) {
 		new TestNode().run();
 	}
 }
+

com/danitheskunk/skunkworks/nodes/BaseTween.java

@@ -2,6 +2,8 @@ package com.danitheskunk.skunkworks.nodes;
 
 public abstract class BaseTween {
 	protected double progress;
+	protected int startFrame;
+	protected int endFrame;
 
 	public BaseTween() {
 		progress = 0;
@@ -11,5 +13,10 @@ public abstract class BaseTween {
 		this.progress = progress;
 	}
 
+	public void delay(int frames) {
+		startFrame += frames;
+		endFrame += frames;
+	}
+
 	protected abstract void apply();
 }

com/danitheskunk/skunkworks/nodes/Node.java

@@ -56,12 +56,13 @@ public class Node implements Iterable<Node> {
 		return Vec2f.add(parent.getAbsolutePos(), pos);
 	}
 
-	public Node getRoot() {
+	public NodeRoot getRoot() {
 		var node = this;
 		while(node.parent != null) {
 			node = node.parent;
 		}
-		return node;
+		//todo: check if right class
+		return (NodeRoot) node;
 	}
 
 	@Override
@@ -69,14 +70,29 @@ public class Node implements Iterable<Node> {
 		return children.iterator();
 	}
 
-	public class TweenPos extends BaseTween {
-		private final Vec2f start;
-		private final Vec2f end;
+	public int getCurrentFrame() {
+		return getRoot().getCurrentFrame();
+	}
 
-		public TweenPos(Vec2f start, Vec2f end) {
-			this.start = start;
-			this.end = end;
-		}
+	protected void prepareTween(BaseTween tween, int frames) {
+		var root = getRoot();
+		tween.startFrame = root.getCurrentFrame();
+		tween.endFrame = tween.startFrame + frames;
+	}
+
+	public TweenPos tweenPos(Vec2f to, int frames) {
+		var tween = new TweenPos();
+		tween.start = pos;
+		tween.end = to;
+		prepareTween(tween, frames);
+		getRoot().getTweener().add(tween);
+		return tween;
+	}
+
+
+	public class TweenPos extends BaseTween {
+		private Vec2f start;
+		private Vec2f end;
 
 		@Override
 		protected void apply() {

com/danitheskunk/skunkworks/nodes/NodeRoot.java

@@ -1,5 +1,25 @@
 package com.danitheskunk.skunkworks.nodes;
 
-public class NodeRoot extends Node {
+import com.danitheskunk.skunkworks.Timestep;
+import com.danitheskunk.skunkworks.Vec2f;
 
+public class NodeRoot extends Node {
+	private Tweener tweener;
+
+	public NodeRoot() {
+		tweener = new Tweener(Timestep.FIXED);
+	}
+
+	@Override
+	public int getCurrentFrame() {
+		return tweener.getCurrentFrame();
+	}
+
+	public void tick() {
+		tweener.tick();
+	}
+
+	public Tweener getTweener() {
+		return tweener;
+	}
 }

com/danitheskunk/skunkworks/nodes/Tweener.java

@@ -2,10 +2,46 @@ package com.danitheskunk.skunkworks.nodes;
 
 import com.danitheskunk.skunkworks.Timestep;
 
+import java.util.ArrayList;
+import java.util.List;
+
 public class Tweener {
 	private Timestep timestepMode;
+	private List<BaseTween> tweens;
+	private int currentFrame;
 
 	public Tweener(Timestep timestepMode) {
 		this.timestepMode = timestepMode;
+		this.tweens = new ArrayList<>();
+		this.currentFrame = 0;
+	}
+
+	public int getCurrentFrame() {
+		return currentFrame;
+	}
+
+	public void tick() {
+		var toRemove = new ArrayList<BaseTween>();
+		for(var tween : tweens) {
+			if(currentFrame >= tween.startFrame &&
+				currentFrame <= tween.endFrame) {
+				var len = tween.endFrame - tween.startFrame;
+				var off = currentFrame - tween.startFrame;
+				var progress = (double) off / (double) len;
+				tween.setProgress(progress);
+				tween.apply();
+			}
+			if(currentFrame == tween.endFrame) {
+				toRemove.add(tween);
+			}
+		}
+		for(var tween : toRemove) {
+			tweens.remove(tween);
+		}
+		++currentFrame;
+	}
+
+	public void add(BaseTween tween) {
+		tweens.add(tween);
 	}
 }