Fix collision detection

frontend/src/scripts/shapes/types/circle.ts

@@ -36,6 +36,6 @@ export class Circle implements IShape {
   }
 
   public clone(): Circle {
-    return new Circle(this.center, this.radius);
+    return new Circle(vec2.clone(this.center), this.radius);
   }
 }

frontend/src/scripts/shapes/types/tunnel-shape.ts

@@ -3,6 +3,7 @@ import { BoundingBox } from '../bounding-box';
 import { clamp01 } from '../../helper/clamp';
 import { mix } from '../../helper/mix';
 import { IShape } from '../i-shape';
+import { rotate90Deg } from '../../helper/rotate-90-deg';
 
 export class TunnelShape implements IShape {
   public readonly isInverted = true;
@@ -39,8 +40,49 @@ export class TunnelShape implements IShape {
     return new BoundingBox(this, xMin, xMax, yMin, yMax);
   }
 
-  public normal(from: vec2): vec2 {
-    throw new Error('Unimplemented');
+  public normal(target: vec2): vec2 {
+    const targetFromDelta = vec2.subtract(vec2.create(), target, this.from);
+
+    const h = clamp01(
+      vec2.dot(targetFromDelta, this.toFromDelta) /
+        vec2.dot(this.toFromDelta, this.toFromDelta)
+    );
+
+    let diff = vec2.create();
+
+    if (h == 1) {
+      vec2.subtract(diff, target, this.to);
+    } else if (h == 0) {
+      vec2.subtract(diff, target, this.from);
+    } else {
+      const side = Math.sign(
+        this.toFromDelta.x * targetFromDelta.y -
+          this.toFromDelta.y * targetFromDelta.x
+      );
+
+      const normal = rotate90Deg(this.toFromDelta);
+      vec2.normalize(normal, normal);
+
+      const translatedFrom = vec2.add(
+        vec2.create(),
+        this.from,
+        vec2.scale(vec2.create(), normal, side * this.fromRadius)
+      );
+
+      const translatedTo = vec2.add(
+        vec2.create(),
+        this.to,
+        vec2.scale(vec2.create(), normal, side * this.toRadius)
+      );
+
+      diff = rotate90Deg(
+        vec2.subtract(vec2.create(), translatedTo, translatedFrom)
+      );
+
+      vec2.scale(diff, diff, side);
+    }
+
+    return vec2.normalize(diff, diff);
   }
 
   public distance(target: vec2): number {
@@ -60,6 +102,11 @@ export class TunnelShape implements IShape {
   }
 
   public clone(): TunnelShape {
-    return new TunnelShape(this.from, this.to, this.fromRadius, this.toRadius);
+    return new TunnelShape(
+      vec2.clone(this.from),
+      vec2.clone(this.to),
+      this.fromRadius,
+      this.toRadius
+    );
   }
 }