tests: Add coroutine examples

excaliburjs · Jul 15, 2024 · 963ab8b · 963ab8b
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diff --git a/sandbox/tests/coroutine/index.html b/sandbox/tests/coroutine/index.html
@@ -0,0 +1,13 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>Coroutine Animation Example</title>
+  </head>
+  <body>
+    <script src="../../lib/excalibur.js"></script>
+    <script src="./index.js"></script>
+  </body>
+</html>
diff --git a/sandbox/tests/coroutine/index.ts b/sandbox/tests/coroutine/index.ts
@@ -0,0 +1,54 @@
+var game = new ex.Engine({
+  width: 600,
+  height: 400,
+  displayMode: ex.DisplayMode.FitScreenAndFill
+});
+
+var actor = new ex.Actor({
+  pos: ex.vec(300, 300),
+  width: 100,
+  height: 100,
+  color: ex.Color.Red
+});
+
+var fadeBy = (actor: ex.Actor, fadeChange: number, durationSeconds: number) => {
+  // coroutines start automatically
+  return ex.coroutine(function* () {
+    let duration = durationSeconds * 1000; // milliseconds
+    let fadeChangeRate = fadeChange / duration;
+    let targetOpacity = actor.graphics.opacity + fadeChange;
+    while (duration > 0) {
+      const elapsed = yield;
+      duration -= elapsed;
+      actor.graphics.opacity += fadeChangeRate * elapsed;
+    }
+    actor.graphics.opacity = targetOpacity;
+  });
+};
+
+var moveByVec = (actor: ex.Actor, change: ex.Vector, durationSeconds: number) => {
+  // coroutines start automatically
+  return ex.coroutine(function* () {
+    let duration = durationSeconds * 1000; // milliseconds
+    let rateOfChange = change.scale(1 / duration);
+    let dest = actor.pos.add(change);
+    while (duration > 0) {
+      const elapsed = yield;
+      duration -= elapsed;
+      actor.pos.addEqual(rateOfChange.scale(elapsed));
+    }
+    actor.pos = dest;
+  });
+};
+
+actor.onInitialize = async () => {
+  await moveByVec(actor, ex.vec(100, -100), 0.5);
+  await moveByVec(actor, ex.vec(-100, -100), 0.5);
+  await moveByVec(actor, ex.vec(-100, 100), 0.5);
+  await moveByVec(actor, ex.vec(100, 100), 0.5);
+  await fadeBy(actor, -1.0, 2);
+};
+
+game.currentScene.add(actor);
+
+game.start();