SKScene detect collision before adding to parent

Question

I am working on a game using Sprite Kit and it involves a ball hitting a target (goal). When the ball makes contact with the goal I want the goal to be removed and added again in a different location. That all works but the problem is more often than not (it seems like) the goal spawns right on top of or intersecting the ball. How would I go about preventing this? Thanks in advance and tell me if I need to post my didBeginContact code.

Answer 1

You can avoid this issue by adding the goal at a new location that is relative to the ball's position. First, add these functions...

static inline CGFloat skRandf() {
    return rand() / (CGFloat) RAND_MAX;
}

static inline CGFloat skRand(CGFloat low, CGFloat high) {
    return skRandf() * (high - low) + low;
}

and then this to your didBeginContact...

    CGFloat goalWidth = goal.size.width;
    CGFloat goalHeight = goal.size.height;

    CGFloat maxX = self.frame.size.width - goalWidth;
    CGFloat maxY = self.frame.size.height - goalHeight;

    CGFloat dx = MAX(maxX-kMinDistanceFromBall-_ball.position.x, 0) + MAX(ball.position.x-kMinDistanceFromBall, 0);
    CGFloat dy = MAX(maxY-kMinDistanceFromBall-_ball.position.y, 0) + MAX(ball.position.y-kMinDistanceFromBall, 0);

    CGFloat newX = ball.position.x + MIN(maxX-ball.position.x, kMinDistanceFromBall) + skRand(0, dx);
    CGFloat newY = ball.position.y + MIN(maxY-ball.position.y, kMinDistanceFromBall) + skRand(0, dy);

    if (newX > maxX) {
        newX -= maxX;
    }

    if (newY > maxY) {
        newY -= maxY;
    }

    goal.position = CGPointMake (newX+goalWidth/2, newY+goalHeight/2);