add terrain collision

src/satx.js

@@ -1,7 +1,7 @@
 import SAT from 'sat'
 
 export default class SATX {
-  static colliding(collider1, collider2) {
+  static collideObject(collider1, collider2) {
     if (collider1 instanceof SAT.Circle && collider2 instanceof SAT.Circle) {
       return SAT.testCircleCircle(collider1, collider2)
     }
@@ -20,4 +20,8 @@ export default class SATX {
 
     return false
   }
+
+  static collideObjects(collider1, colliders) {
+    return colliders.some((c) => this.collideObject(collider1, c))
+  }
 }