WIP

engine/system/physics.ts

@@ -0,0 +1,115 @@
+import type { Circle } from "#/engine/Circle.ts";
+import type { Polygon } from "#/engine/Polygon.ts";
+import type { Rect } from "#/engine/Rect.ts";
+import $ from "#/engine/Scene.ts";
+import { createVector, type Vector } from "#/engine/Vector.ts";
+
+export enum Shape {
+	Cirle,
+	Rect,
+	Polygon,
+}
+
+const CIRCLE = Shape.Cirle;
+const RECT = Shape.Rect;
+const POLYGON = Shape.Polygon;
+
+type ShapeType = Shape.Cirle | Shape.Rect | Shape.Polygon;
+
+type CollisionBuffer = {
+	size: number;
+	mask: number;
+	cursor: number;
+	pool: Array<Collision>;
+	slice: Array<Collision>;
+};
+
+function createCollisionBuffer(size: number): CollisionBuffer {
+	if ((size & (size - 1)) !== 0) {
+		throw new Error("size must be a power of two");
+	}
+
+	const pool: Array<Collision> = [];
+	for (let i = 0; i < size; i++) {
+		pool.push(createCollision());
+	}
+
+	return {
+		size,
+		mask: size - 1,
+		cursor: 0,
+		pool,
+		slice: [],
+	};
+}
+
+function bufferNext(buffer: CollisionBuffer): Collision {
+	return buffer.pool[buffer.cursor++ & buffer.mask];
+}
+
+function bufferSliceReset(buffer: CollisionBuffer): void {
+	buffer.slice.length = 0;
+}
+
+function bufferSliceAdd(buffer: CollisionBuffer): Collision {
+	const next = bufferNext(buffer);
+	buffer.slice.push(next);
+
+	return next;
+}
+
+export type Collider = {
+	shape: ShapeType;
+	body: Circle | Rect | Polygon;
+	buffer: CollisionBuffer;
+};
+
+export type Collision = {
+	cid: string;
+	normal: Vector;
+	position: Vector;
+	depth: 0;
+	angle: 0;
+};
+
+function createCollision(): Collision {
+	return {
+		cid: "",
+		normal: createVector(),
+		position: createVector(),
+		depth: 0,
+		angle: 0,
+	};
+}
+
+export function createCollider(
+	shape: ShapeType,
+	body: Circle | Rect | Polygon,
+	bufferSize: number = 8,
+): Collider {
+	return {
+		shape,
+		body,
+		buffer: createCollisionBuffer(bufferSize),
+	};
+}
+
+export function moveAndCollide(
+	id: string,
+	velocity: Vector,
+	delta: number,
+): Array<Collision> {
+	const colliders = $<Collider>("collider")!;
+	const self = colliders.get(id)!.value;
+	bufferSliceReset(self.buffer);
+
+	for (const [cid, _] of colliders.entries()) {
+		if (cid === id) {
+			continue;
+		}
+		const collisoin = bufferSliceAdd(self.buffer);
+		collisoin.cid = cid;
+	}
+
+	return self.buffer.slice;
+}