Ensure collision detection triggers only once per collision

Question

I am trying collision detection without using Box2d, so i used a inbuilt function CCRectIntersectsRect() using this function when i decrement the count it gets reduced to negative values in a single collision. (when the ball touches hero and when the ball crosses hero.)

All i want is to schedule it in someway so that the count-- gets called once only.

For complete source code how to use box2d for collision detection in cocos2d-x

CCRect bom= ball->boundingBox();
CCRect gon= hero->boundingBox();

if(CCRect::CCRectIntersectsRect(bom,gon))
{
    count--;
}

Answer 1

Create a persistent bool variable called colliding, and use it like this:

if(CCRect::CCRectIntersectsRect(bom,gon))
{
    if (!colliding)
        count--;
    colliding = true;
}
else
    colliding = false;

Here's the fix for the code you provided in the comments below:

CCRect bom= roll->boundingBox();
CCRect gon= hero->boundingBox();
static bool colliding=false;
if(CCRect::CCRectIntersectsRect(bom,gon))
{
    if (!colliding)
    {
        intersection();
        colliding = true;
    }
}
else
    colliding = false;

Answer 2

initialize count with 1 if(CCRect::CCRectIntersectsRect(bom,gon) && count > 0) { count--; }