animated sprites

animation/sprite.ts

@@ -0,0 +1,45 @@
+import { Vector } from "../geometry/vector.ts";
+
+export class SpriteAnimation {
+  image: HTMLImageElement;
+  origin: Vector;
+  constructor(
+    private imageUrl: string,
+    private cellWidth: number,
+    private cellHeight: number,
+    private cellCountX: number,
+    private cellCountY: number,
+    private timing = 1,
+    private scale = 1,
+  ) {
+    this.image = new Image();
+    this.image.src = this.imageUrl;
+    this.origin = new Vector();
+  }
+
+  private _frameCount = 0;
+  private get frameCount() {
+    return this._frameCount += this.timing;
+  }
+
+  getCell() {
+    const time = Math.floor(this.frameCount);
+    const x = (time % this.cellCountX) * this.cellWidth;
+    const y = (Math.floor(time / this.cellCountX) % this.cellCountY) *
+      this.cellHeight;
+    return { x, y };
+  }
+
+  draw() {
+    const { x, y } = this.getCell();
+    doodler.drawSprite(
+      this.image,
+      new Vector(x, y),
+      this.cellWidth,
+      this.cellHeight,
+      this.origin,
+      this.cellWidth * this.scale,
+      this.cellHeight * this.scale,
+    );
+  }
+}