get "cats" up there

1 files changed, 46 insertions, 0 deletions

diff --git a/static/src/engine/render.ts b/static/src/engine/render.ts
new file mode 100644
index 0000000..8f0343a
--- /dev/null
+++ b/static/src/engine/render.ts
@@ -0,0 +1,46 @@
+import {
+  ComponentType,
+  PositionComponent,
+  TrailingPositionComponent,
+} from "./component";
+import { Game } from "./game";
+import { System, SystemType } from "./system";
+import { drawLaserPen } from "laser-pen";
+
+export class RenderSystem extends System {
+  constructor(private readonly canvas: HTMLCanvasElement) {
+    super(SystemType.RENDER);
+  }
+
+  public set_world_dimensions(width: number, height: number) {
+    this.canvas.width = width;
+    this.canvas.height = height;
+  }
+
+  public update(_dt: number, game: Game) {
+    const ctx = this.canvas.getContext("2d");
+    if (ctx === null) return;
+    ctx.clearRect(0, 0, this.canvas.width, this.canvas.height);
+
+    game.for_each_entity_with_component(ComponentType.RENDERABLE, (entity) => {
+      if (ComponentType.TRAILING_POSITION in entity.components) {
+        const trailing_position = entity.components[
+          ComponentType.TRAILING_POSITION
+        ] as TrailingPositionComponent;
+        if (trailing_position.trails.length < 3) return;
+        drawLaserPen(ctx, trailing_position.trails);
+        return;
+      }
+
+      if (ComponentType.POSITION in entity.components) {
+        const position = entity.components[
+          ComponentType.POSITION
+        ] as PositionComponent;
+        ctx.beginPath();
+        ctx.arc(position.x, position.y, 50, 0, 2 * Math.PI);
+        ctx.stroke();
+        return;
+      }
+    });
+  }
+}