Why will the physical set of sprites be different from iOS 7.x vs iOS 8.x ???
I have a simple spritekit script ... I have 2 static contacts, and between them I have sprites that are connected by a spring joint, dropping an object on this elastic rope will behave like a trampoline, everything looks fine on iOS 7.x, until I started testing iOS 8.x. I tested on similar devices: 2 iphones 5s and 2 ipod touch 5th generation with every 7 and 8, I get the same fps, having the same number of nodes.
I tried all kinds of joints, factors, gravity, speed and every time I run this simple piece of code on different devices on 7.x. I get similar behavior, but if I run it on 8.x devices, the “elasticity” is different from the spring joint, stiffer on 7.x, the elastic will bend 8.x more without anything on it, but if you add several balls on it, you can even see a larger effect on 8.x. before they ask me, here is the skcene code
#define kFrequency 30.0f #define kDamping 0.0f #define kNodes 20 typedef NS_OPTIONS(uint32_t, CategoryMask) { CategoryMaskBall = 1 << 0, CategoryMaskPin = 1 << 1, CategoryMaskElastic = 1 << 2, CategoryMaskBorder = 1 << 3 }; @implementation SimpleGameScene -(void)didMoveToView:(SKView *)view { self.backgroundColor = [SKColor blackColor]; self.physicsWorld.gravity = CGVectorMake(0.0, -4.9); NSMutableArray *nodes=[NSMutableArray arrayWithCapacity:kNodes+2]; SKSpriteNode *pin = [self addPin:CGPointMake(self.size.width/2, self.size.height/4)]; [self addChild:pin]; [nodes addObject:pin]; for( int i = 1; i<=kNodes; i++) { SKSpriteNode *elastic = [self addElastic:CGPointMake(self.size.width/2+i*(pin.size.width+1), self.size.height/4)]; [self addChild:elastic]; [nodes addObject:elastic]; } SKSpriteNode *pin2 = [self addPin:CGPointMake(self.size.width/2+(kNodes+1)*(pin.size.width+1), self.size.height/4)]; [self addChild:pin2]; [nodes addObject:pin2]; for( int i = 1; i<=kNodes+1; i++) { SKSpriteNode *nodeA = [nodes objectAtIndex:i-1]; SKSpriteNode *nodeB = [nodes objectAtIndex:i]; [self addSpringJointFrom:nodeA to:nodeB]; } } -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { for (UITouch *touch in touches) { SKSpriteNode *ball = [self spawnBallAt:[touch locationInNode:self]]; [self addChild:ball]; } } -(SKSpriteNode*) spawnBallAt:(CGPoint)location { SKSpriteNode *ball = [SKSpriteNode spriteNodeWithTexture:[[SKTextureAtlas atlasNamed:@"game"] textureNamed:@"circle"]]; ball.position = CGPointMake( location.x, location.y); ball.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:ball.size.width/2]; ball.physicsBody.dynamic = YES; ball.physicsBody.affectedByGravity = YES; ball.physicsBody.mass = 40.0f; ball.physicsBody.categoryBitMask = CategoryMaskBall; ball.physicsBody.collisionBitMask = CategoryMaskElastic ; ball.physicsBody.contactTestBitMask = 0; ball.name = @"ball"; return ball; } -(SKSpriteNode*) addPin:(CGPoint) location { SKSpriteNode *pin = [SKSpriteNode spriteNodeWithTexture:[[SKTextureAtlas atlasNamed:@"game"] textureNamed:@"pin"]]; pin.position = location; pin.zPosition = 1; CGFloat offsetX = pin.size.width * pin.anchorPoint.x; CGFloat offsetY = pin.size.height * pin.anchorPoint.y; CGMutablePathRef path = CGPathCreateMutable(); CGFloat side = pin.size.width; CGPathMoveToPoint(path, NULL, 0 - offsetX, side - offsetY); CGPathAddLineToPoint(path, NULL, side - offsetX, side - offsetY); CGPathAddLineToPoint(path, NULL, side - offsetX, 0 - offsetY); CGPathAddLineToPoint(path, NULL, 0 - offsetX, 0 - offsetY); CGPathCloseSubpath(path); pin.physicsBody = [SKPhysicsBody bodyWithPolygonFromPath:path]; pin.physicsBody.affectedByGravity = NO; pin.physicsBody.dynamic = NO; pin.physicsBody.categoryBitMask = CategoryMaskPin; pin.physicsBody.collisionBitMask = 0; pin.physicsBody.contactTestBitMask = 0; CGPathRelease(path); return pin; } -(SKSpriteNode*) addElastic:(CGPoint) location { SKSpriteNode *elastic = [SKSpriteNode spriteNodeWithTexture:[[SKTextureAtlas atlasNamed:@"game"] textureNamed:@"elastic"]]; elastic.position = location; elastic.zPosition = 1; CGFloat offsetX = elastic.frame.size.width * elastic.anchorPoint.x; CGFloat offsetY = elastic.frame.size.height * elastic.anchorPoint.y; CGMutablePathRef path = CGPathCreateMutable(); CGFloat side = elastic.size.width; CGPathMoveToPoint(path, NULL, 0 - offsetX, side - offsetY); CGPathAddLineToPoint(path, NULL, side - offsetX, side - offsetY); CGPathAddLineToPoint(path, NULL, side - offsetX, 0 - offsetY); CGPathAddLineToPoint(path, NULL, 0 - offsetX, 0 - offsetY); CGPathCloseSubpath(path); elastic.physicsBody = [SKPhysicsBody bodyWithPolygonFromPath:path]; elastic.physicsBody.affectedByGravity = YES; elastic.physicsBody.allowsRotation = NO; elastic.physicsBody.dynamic = YES; elastic.physicsBody.mass = 1.0f; elastic.physicsBody.categoryBitMask = CategoryMaskElastic; elastic.physicsBody.collisionBitMask = CategoryMaskBall; elastic.physicsBody.contactTestBitMask = 0; CGPathRelease(path); return elastic; } - (void) addSpringJointFrom:(SKSpriteNode*) nodeA to:(SKSpriteNode*) nodeB { SKPhysicsJointSpring *joint = [SKPhysicsJointSpring jointWithBodyA:nodeA.physicsBody bodyB:nodeB.physicsBody anchorA:nodeA.position anchorB:nodeB.position]; joint.frequency = kFrequency;