Add basic multiplayer

frontend/src/scripts/objects/camera.ts

@@ -0,0 +1,36 @@
+import { vec2 } from 'gl-matrix';
+import { CommandExecutors, GameObject, Rectangle, settings } from 'shared';
+import { RenderCommand } from '../commands/types/render';
+
+export class Camera extends GameObject {
+  private static readonly inViewAreaSize = settings.inViewAreaSize;
+  private _viewArea = new Rectangle();
+
+  protected commandExecutors: CommandExecutors = {
+    [RenderCommand.type]: this.draw.bind(this),
+  };
+
+  constructor(public center: vec2 = vec2.create()) {
+    super(null);
+  }
+
+  public get viewArea(): Rectangle {
+    return this._viewArea;
+  }
+
+  private draw(c: RenderCommand) {
+    const canvasAspectRatio = c.renderer.canvasSize.x / c.renderer.canvasSize.y;
+
+    this._viewArea.topLeft = vec2.fromValues(
+      this.center.x - this._viewArea.size.x / 2,
+      this.center.y + this._viewArea.size.y / 2
+    );
+
+    this._viewArea.size = vec2.fromValues(
+      Math.sqrt(Camera.inViewAreaSize * canvasAspectRatio),
+      Math.sqrt(Camera.inViewAreaSize / canvasAspectRatio)
+    );
+
+    c.renderer.setViewArea(this._viewArea.topLeft, this._viewArea.size);
+  }
+}