time for a snapshot

workshop/steps/06-ray-vs-aabb/given.ts

@@ -0,0 +1,28 @@
+// Finished in earlier steps — reuse, don't rewrite.
+export type Vec = { x: number; y: number };
+export const vec = (x: number, y: number): Vec => ({ x, y });
+
+export type AABB = { x: number; y: number; w: number; h: number };
+export type Span = { entry: number; exit: number };
+
+/** Step 05, finished. */
+export function sweepInterval(
+	p: number,
+	v: number,
+	min: number,
+	max: number,
+): Span | null {
+	if (v === 0) {
+		return min <= p && p <= max
+			? { entry: -Infinity, exit: Infinity }
+			: null;
+	}
+
+	let t1 = (min - p) / v;
+	let t2 = (max - p) / v;
+	if (t1 > t2) {
+		[t1, t2] = [t2, t1];
+	}
+
+	return { entry: t1, exit: t2 };
+}