WIP

engine/lib/geometry.ts

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+import type { AABB } from "#/engine/AABB.ts";
+import type { Circle } from "#/engine/Circle.ts";
+import type { Vector } from "#/engine/Vector.ts";
+
+export function isPointInCircle(point: Vector, circle: Circle): boolean {
+	const dx = point.x - circle.position.x;
+	const dy = point.y - circle.position.y;
+
+	return dx * dx + dy * dy <= circle.radius ** 2;
+}
+
+export function isPointInAABB(point: Vector, aabb: AABB): boolean {
+	const rx = aabb.position.x;
+	const ry = aabb.position.y;
+
+	return (
+		point.x >= rx &&
+		point.x <= rx + aabb.width &&
+		point.y >= ry &&
+		point.y <= ry + aabb.height
+	);
+}
+
+export function circleIntersectCircle(a: Circle, b: Circle): boolean {
+	const dx = a.position.x - b.position.x;
+	const dy = a.position.y - b.position.y;
+
+	return dx * dx + dy * dy <= (a.radius + b.radius) ** 2;
+}
+
+export function AABBIntersectAABB(a: AABB, b: AABB): boolean {
+	const ax = a.position.x;
+	const ay = a.position.y;
+	const bx = b.position.x;
+	const by = b.position.y;
+
+	return (
+		ax <= bx + b.width &&
+		ax + a.width >= bx &&
+		ay <= by + b.height &&
+		ay + a.height >= by
+	);
+}
+
+export function circleIntersectAABB(circle: Circle, aabb: AABB): boolean {
+	const cx = circle.position.x;
+	const cy = circle.position.y;
+	const rx = aabb.position.x;
+	const ry = aabb.position.y;
+
+	const dx = cx - Math.max(rx, Math.min(cx, rx + aabb.width));
+	const dy = cy - Math.max(ry, Math.min(cy, ry + aabb.height));
+
+	return dx * dx + dy * dy <= circle.radius ** 2;
+}
+
+export function circleContainsCircle(a: Circle, b: Circle): boolean {
+	const dx = a.position.x - b.position.x;
+	const dy = a.position.y - b.position.y;
+	const distance = Math.sqrt(dx * dx + dy * dy);
+
+	return a.radius >= b.radius + distance;
+}
+
+export function AABBContainsAABB(a: AABB, b: AABB): boolean {
+	const ax = a.position.x;
+	const ay = a.position.y;
+	const bx = b.position.x;
+	const by = b.position.y;
+
+	return (
+		ax <= bx &&
+		ax + a.width >= bx + b.width &&
+		ay <= by &&
+		ay + a.height >= by + b.height
+	);
+}
+
+export function AABBContainsCircle(aabb: AABB, circle: Circle): boolean {
+	const rx = aabb.position.x;
+	const ry = aabb.position.y;
+	const cx = circle.position.x;
+	const cy = circle.position.y;
+
+	return (
+		rx <= cx - circle.radius &&
+		rx + aabb.width >= cx + circle.radius &&
+		ry <= cy - circle.radius &&
+		ry + aabb.height >= cy + circle.radius
+	);
+}
+
+export function circleContainsAABB(circle: Circle, aabb: AABB): boolean {
+	const radiusSquare = circle.radius ** 2;
+
+	const dax = aabb.position.x - circle.position.x;
+	const day = aabb.position.y - circle.position.y;
+	if (dax * dax + day * day > radiusSquare) {
+		return false;
+	}
+
+	const dbx = aabb.position.x + aabb.width - circle.position.x;
+	const dby = aabb.position.y - circle.position.y;
+	if (dbx * dbx + dby * dby > radiusSquare) {
+		return false;
+	}
+
+	const dcx = aabb.position.x - circle.position.x;
+	const dcy = aabb.position.y + aabb.height - circle.position.y;
+	if (dcx * dcx + dcy * dcy > radiusSquare) {
+		return false;
+	}
+
+	const ddx = aabb.position.x + aabb.width - circle.position.x;
+	const ddy = aabb.position.y + aabb.height - circle.position.y;
+	if (ddx * ddx + ddy * ddy > radiusSquare) {
+		return false;
+	}
+
+	return true;
+}