Rectangle and Circle collision detection

Question

I am trying to do collision detection between a rectangle and a circle. I came up with this method:

-(BOOL) isCollidingRect:(CCSprite *) spriteOne WithSphere:(CC         


        

Answer 1

This is not a solution for those who use Cocos2d-ObjC, but will help for Cocos2d-x devs (for instance, personally I found this topic because was searching for the same for my c++ game).

Cocos2d-x has method "intersectsCircle" for Rect class.

Here is how I solved in my c++ project almost the same problem as one described by you:

bool ObstacleEntity::hasCollisionAgainst(cocos2d::Sprite *spr)
{
    cocos2d::Rect rect = cocos2d::Rect( spr->getPositionX(), spr->getPositionY(), spr->getBoundingBox().size.width, spr->getBoundingBox().size.height);

    float rw = this->getBoundingBox().size.width / 2;
    float rh = this->getBoundingBox().size.height / 2;

    float radius = ( rw > rh ) ? rw : rh;
    cocos2d::Vec2 center( this->getPositionX() + rw, this->getPositionY() + rh );

    return rect.intersectsCircle( center, radius );
}

Passed Sprite here is rectangle, while ObstacleEntity always is almost ideally round. Note that anchor points for all entities are set to lower left corner in my case.

Answer 2

You can use CGRectIntersectsRect to achieve this.

-(BOOL) isCollidingRect:(CCSprite *) spriteOne WithSphere:(CCSprite *) spriteTwo {
    return CGRectIntersectsRect([spriteOne boundingBox],[spriteTwo boundingBox]);
}

It is not pixel perfect but as i understand that is not necessary in this case.