feat: threading

src/Project.ts

@@ -12,6 +12,7 @@ import {
   waitFor,
   waitUntil,
   sequence,
+  threads,
 } from './animations';
 
 Konva.autoDrawEnabled = false;
@@ -75,7 +76,10 @@ export class Project extends Stage {
     this.scenes.forEach(scene => scene.layer.destroy());
     this.scenes = [];
     this.frame = 0;
-    this.runner = this.runnerFactory(this);
+    this.runner = this.threads(join => {
+      this.join = join;
+      return this.runnerFactory(this);
+    });
   }
 
   public next(): boolean {
@@ -94,6 +98,8 @@ export class Project extends Stage {
     return frames / this.framesPerSeconds;
   }
 
+  public join: (...runners: Generator[]) => Generator;
+  public threads = threads;
   public waitFor = waitFor;
   public waitUntil = waitUntil;
   public tween = tween;

src/animations/index.ts

@@ -5,4 +5,5 @@ export * from './surfaceTransition';
 export * from './tween';
 export * from './TimeTween';
 export * from './scheduling';
-export * from './sequence';
+export * from './sequence';
+export * from './threads';

src/animations/threads.ts

@@ -0,0 +1,29 @@
+export function* threads(
+  factory: (join: (...tasks: Generator[]) => Generator) => Generator,
+): Generator {
+  let runners: Generator[] = [];
+  const join = function* (...tasks: Generator[]): Generator {
+    while (tasks.find(runner => runners.includes(runner))) {
+      yield;
+    }
+  };
+  runners.push(factory(join));
+  while (runners.length > 0) {
+    const newRunners = [];
+    for (let i = 0; i < runners.length; i++) {
+      const runner = runners[i];
+      const result = runner.next();
+
+      if (result.value?.next) {
+        if (!result.done) {
+          runners.push(runner);
+        }
+        runners.push(result.value);
+      } else if (!result.done) {
+        newRunners.push(runner);
+      }
+    }
+    runners = newRunners;
+    if (runners.length > 0) yield;
+  }
+}