Add start of ship rendering

js/world/ship.mjs

@@ -0,0 +1,35 @@
+import Module from './module.mjs';
+import Body from './body.mjs';
+
+export default class Ship extends Body {
+	constructor(x, y) {
+		super(x, y, 0);
+
+		this.com = [0, 0];
+		this.modules = new Set();
+	}
+
+	tick() {
+
+	}
+
+	addModule(x, y, properties, options) {
+		let module = new Module(x, y, {...properties, ...options});
+		this.modules.add(module);
+		this.refreshShape();
+	}
+
+	deleteModule(module) {
+		this.modules.delete(module);
+		this.refreshShape();
+	}
+
+	refreshShape() {
+		let points = [];
+		this.modules.forEach(m => points.push([m.x, m.y, m.mass]));
+		this.mass = points.reduce((a, [,,b]) => a + b, 0);
+		this.com = points.reduce(([ax, ay], b) =>
+			[ax + b.x * b.mass, ay + b.y * b.mass], [0, 0])
+			.map(x => x / this.mass);
+	}
+}