Collision tests

README.md

@@ -3,7 +3,6 @@
 [![Build Status](https://semaphoreci.com/api/v1/pauloddr/aa-rectangle-javascript/branches/master/shields_badge.svg)](https://semaphoreci.com/pauloddr/aa-rectangle-javascript)
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 ```javascript
 var box = new AARectangle(width, height, x, y);

lib/aa-rectangle.js

@@ -1,6 +1,6 @@
 'use strict';
 
-const {segmentsCollide} = require('./collision-helpers');
+const {segmentCollision} = require('./collision-helpers');
 
 let AARectangleId = 0;
 
@@ -114,19 +114,21 @@ class AARectangle {
   collision (box) {
     this.update();
     box.update();
+    return this.collisionX(box) && this.collisionY(box);
+  }
 
-    const collidesInX = segmentsCollide(
+  collisionX (box) {
+    return segmentCollision(
       this.globalX1, this.globalX2,
       box.globalX1, box.globalX2
     );
-    if (!collidesInX) {
-      return false;
-    }
-    const collidesInY = segmentsCollide(
+  }
+
+  collisionY (box) {
+    return segmentCollision(
       this.globalY1, this.globalY2,
       box.globalY1, box.globalY2
     );
-    return collidesInY;
   }
 
 }

lib/collision-helpers.js

@@ -1,8 +1,8 @@
 'use strict';
 
-module.exports = {segmentsCollide};
+module.exports = {segmentCollision};
 
-function segmentsCollide (segment1_start, segment1_end, segment2_start, segment2_end) {
-  return segment1_end >= segment2_start &&
-         segment1_start <= segment2_end;
+function segmentCollision (segment1Start, segment1End, segment2Start, segment2End) {
+  return segment1End >= segment2Start &&
+         segment1Start <= segment2End;
 }

test/aa-rectangle.js

@@ -60,7 +60,7 @@ describe('AARectangle', function () {
     box3.add(box4);
     box4.add(box5);
 
-    it('runs fast!', function () {
+    it('runs fast', function () {
       this.retries(10); // allows engine to optimize
       box2.flipX();
       box3.flipY();
@@ -69,7 +69,7 @@ describe('AARectangle', function () {
         time1 = now();
         box4.update();
         time2 = now();
-        expect(time2 - time1).to.be.at.most(0.009); // 9 nanoseconds
+        expect(time2 - time1).to.be.at.most(0.009); // 9 nanoseconds ~ 111,111 op/sec
       }
       box2.unflipX();
       box3.unflipY();
@@ -175,4 +175,56 @@ describe('AARectangle', function () {
 
   });
 
+  describe('#collision', function () {
+
+    it('returns true if a box is completely inside another', function () {
+      let box1 = new AARectangle(100, 100, 1, 1);
+      let box2 = new AARectangle(2, 2, -40, -40);
+      expect(box1.collision(box2)).to.equal(true);
+    });
+
+    it('returns true if sides and bases touch', function () {
+      let box1 = new AARectangle(2, 2, 1, 1);
+      let box2 = new AARectangle(2, 2, -1, -1);
+      expect(box1.collision(box2)).to.equal(true);
+    });
+
+    it('returns false if bases touch but sides do not', function () {
+      let box1 = new AARectangle(2, 2, 3, 1);
+      let box2 = new AARectangle(2, 2, -1, -1);
+      expect(box1.collision(box2)).to.equal(false);
+    });
+
+    it('returns false if sides touch but bases do not', function () {
+      let box1 = new AARectangle(2, 2, 1, 3);
+      let box2 = new AARectangle(2, 2, -1, -1);
+      expect(box1.collision(box2)).to.equal(false);
+    });
+
+    describe('with parent', function () {
+
+      it('returns true if box is dragged towards another by parent position', function () {
+        let parent = new AARectangle(0, 0, 0, 2);
+        let box1 = new AARectangle(2, 2, 1, 3);
+        let box2 = new AARectangle(2, 2, -1, -1);
+        expect(box1.collision(box2)).to.equal(false);
+        parent.add(box2); // parent position will bring box2 closer to box1
+        expect(box1.collision(box2)).to.equal(true);
+      });
+
+      it('returns true if box is dragged towards another by parent translation', function () {
+        let parent = new AARectangle(0, 0, 0, 0);
+        let box1 = new AARectangle(2, 2, 1, 3);
+        let box2 = new AARectangle(2, 2, -1, -1);
+        expect(box1.collision(box2)).to.equal(false);
+        parent.add(box2);
+        expect(box1.collision(box2)).to.equal(false);
+        parent.translateY = 2; // parent translation will bring box2 closer to box1
+        expect(box1.collision(box2)).to.equal(true);
+      });
+
+    });
+
+  });
+
 });

test/collision-helpers.js

@@ -1,30 +1,30 @@
 'use strict';
 
-const {segmentsCollide} = require('../lib/collision-helpers');
+const {segmentCollision} = require('../lib/collision-helpers');
 const expect = require('chai').expect;
 
 describe('CollisionHelpers', function () {
 
-  describe('.segmentsCollide', function () {
+  describe('.segmentCollision', function () {
 
     it('returns true if segments touch', function () {
-      expect(segmentsCollide(1, 2, 2, 3)).to.equal(true);
-      expect(segmentsCollide(2, 3, 1, 2)).to.equal(true);
+      expect(segmentCollision(1, 2, 2, 3)).to.equal(true);
+      expect(segmentCollision(2, 3, 1, 2)).to.equal(true);
     });
 
     it('returns true if segments intersect', function () {
-      expect(segmentsCollide(1, 2.5, 2, 3)).to.equal(true);
-      expect(segmentsCollide(1.9, 3, 1, 2)).to.equal(true);
+      expect(segmentCollision(1, 2.5, 2, 3)).to.equal(true);
+      expect(segmentCollision(1.9, 3, 1, 2)).to.equal(true);
     });
 
     it('returns true if one segment is inside the other', function () {
-      expect(segmentsCollide(1, 5, 2, 3)).to.equal(true);
-      expect(segmentsCollide(2, 3, 1, 5)).to.equal(true);
+      expect(segmentCollision(1, 5, 2, 3)).to.equal(true);
+      expect(segmentCollision(2, 3, 1, 5)).to.equal(true);
     });
 
     it('returns false if segments do not touch or intersect', function () {
-      expect(segmentsCollide(1, 2, 3, 4)).to.equal(false);
-      expect(segmentsCollide(3, 4, 1, 2)).to.equal(false);
+      expect(segmentCollision(1, 2, 3, 4)).to.equal(false);
+      expect(segmentCollision(3, 4, 1, 2)).to.equal(false);
     });
 
   });