a bit of refactoring; importing engine into bun for server

1 files changed, 15 insertions, 0 deletions

diff --git a/engine/utils/rotateVector.ts b/engine/utils/rotateVector.ts
new file mode 100644
index 0000000..82bb54d
--- /dev/null
+++ b/engine/utils/rotateVector.ts
@@ -0,0 +1,15 @@
+import type { Coord2D } from "../interfaces";
+
+/**
+ * ([[cos(θ), -sin(θ),])  ([x,)
+ * ([sin(θ),  cos(θ)] ])  ( y])
+ */
+export const rotateVector = (vector: Coord2D, theta: number): Coord2D => {
+  const rads = (theta * Math.PI) / 180;
+  const [cos, sin] = [Math.cos(rads), Math.sin(rads)];
+
+  return {
+    x: vector.x * cos - vector.y * sin,
+    y: vector.x * sin + vector.y * cos,
+  };
+};