1 files changed, 49 insertions, 12 deletions

diff --git a/engine/components/BoundingBox.ts b/engine/components/BoundingBox.ts
index 5e21b2f..921feb9 100644
--- a/engine/components/BoundingBox.ts
+++ b/engine/components/BoundingBox.ts
@@ -1,6 +1,6 @@
-import { Component, ComponentNames } from ".";
-import type { Coord2D, Dimension2D } from "../interfaces";
-import { dotProduct, rotateVector } from "../utils";
+import { Component, ComponentNames } from '.';
+import type { Coord2D, Dimension2D } from '../interfaces';
+import { dotProduct, rotateVector } from '../utils';
 
 export class BoundingBox extends Component {
   public center: Coord2D;
@@ -15,8 +15,27 @@ export class BoundingBox extends Component {
     this.rotation = rotation ?? 0;
   }
 
-  // https://en.wikipedia.org/wiki/Hyperplane_separation_theorem
   public isCollidingWith(box: BoundingBox): boolean {
+    if (this.rotation == 0 && box.rotation == 0) {
+      const thisTopLeft = this.getTopLeft();
+      const thisBottomRight = this.getBottomRight();
+
+      const thatTopLeft = box.getTopLeft();
+      const thatBottomRight = box.getBottomRight();
+
+      if (
+        thisBottomRight.x <= thatTopLeft.x ||
+        thisTopLeft.x >= thatBottomRight.x ||
+        thisBottomRight.y <= thatTopLeft.y ||
+        thisTopLeft.y >= thatBottomRight.y
+      ) {
+        return false;
+      }
+
+      return true;
+    }
+
+    // https://en.wikipedia.org/wiki/Hyperplane_separation_theorem
     const boxes = [this.getVertices(), box.getVertices()];
     for (const poly of boxes) {
       for (let i = 0; i < poly.length; i++) {
@@ -29,8 +48,8 @@ export class BoundingBox extends Component {
               const projection = dotProduct(normal, vertex);
               return [Math.min(min, projection), Math.max(max, projection)];
             },
-            [Infinity, -Infinity],
-          ),
+            [Infinity, -Infinity]
+          )
         );
 
         if (maxThis < minBox || maxBox < minThis) return false;
@@ -45,20 +64,22 @@ export class BoundingBox extends Component {
       { x: -this.dimension.width / 2, y: -this.dimension.height / 2 },
       { x: -this.dimension.width / 2, y: this.dimension.height / 2 },
       { x: this.dimension.width / 2, y: this.dimension.height / 2 },
-      { x: this.dimension.width / 2, y: -this.dimension.height / 2 },
+      { x: this.dimension.width / 2, y: -this.dimension.height / 2 }
     ]
-      .map((vertex) => rotateVector(vertex, this.rotation))
+      .map((vertex) => rotateVector(vertex, this.rotation)) // rotate
       .map((vertex) => {
+        // translate
         return {
           x: vertex.x + this.center.x,
-          y: vertex.y + this.center.y,
+          y: vertex.y + this.center.y
         };
       });
   }
 
-  public getRotationInPiOfUnitCircle() {
+  public getRotationInPiOfUnitCircle(): number {
     let rads = this.rotation * (Math.PI / 180);
     if (rads >= Math.PI) {
+      // Physics system guarantees rotation \in [0, 360)
       rads -= Math.PI;
     }
     return rads;
@@ -68,17 +89,33 @@ export class BoundingBox extends Component {
     let rads = this.getRotationInPiOfUnitCircle();
     const { width, height } = this.dimension;
 
+    if (rads == 0) return this.dimension;
+
     if (rads <= Math.PI / 2) {
       return {
         width: Math.abs(height * Math.sin(rads) + width * Math.cos(rads)),
-        height: Math.abs(width * Math.sin(rads) + height * Math.cos(rads)),
+        height: Math.abs(width * Math.sin(rads) + height * Math.cos(rads))
       };
     }
 
     rads -= Math.PI / 2;
     return {
       width: Math.abs(height * Math.cos(rads) + width * Math.sin(rads)),
-      height: Math.abs(width * Math.cos(rads) + height * Math.sin(rads)),
+      height: Math.abs(width * Math.cos(rads) + height * Math.sin(rads))
+    };
+  }
+
+  public getTopLeft(): Coord2D {
+    return {
+      x: this.center.x - this.dimension.width / 2,
+      y: this.center.y - this.dimension.height / 2
+    };
+  }
+
+  public getBottomRight(): Coord2D {
+    return {
+      x: this.center.x + this.dimension.width / 2,
+      y: this.center.y + this.dimension.height / 2
     };
   }
 }