BoundingBox of rotating sprite

cocos2d-x
#1

Hi,
I have to check if my point is contained in my spite. So i wrote a something like that:

if(my_sprite->getBoundingBox().containsPoint(point))

my_sprite has a shape of rectangle and is rotating in another function.
But the problem is that getBounding box doesnt return what i want. I will describe my issue:

problem
problem600×600 71.4 KB

#2

The comment of Node::getBoundingBox() is

Returns an AABB (axis-aligned bounding-box) in its parent's coordinate system.

So the behavior is correct. What you need is obb, which is missed. You should implement it yourself.

#3

is there any reference link or hint for this?

#4

The source code are

Rect Node::getBoundingBox() const
{
    Rect rect(0, 0, _contentSize.width, _contentSize.height);
    return RectApplyAffineTransform(rect, getNodeToParentAffineTransform());
}

Rect RectApplyAffineTransform(const Rect& rect, const AffineTransform& anAffineTransform)
{
    float top    = rect.getMinY();
    float left   = rect.getMinX();
    float right  = rect.getMaxX();
    float bottom = rect.getMaxY();
    
    Vec2 topLeft = PointApplyAffineTransform(Vec2(left, top), anAffineTransform);
    Vec2 topRight = PointApplyAffineTransform(Vec2(right, top), anAffineTransform);
    Vec2 bottomLeft = PointApplyAffineTransform(Vec2(left, bottom), anAffineTransform);
    Vec2 bottomRight = PointApplyAffineTransform(Vec2(right, bottom), anAffineTransform);

    float minX = min(min(topLeft.x, topRight.x), min(bottomLeft.x, bottomRight.x));
    float maxX = max(max(topLeft.x, topRight.x), max(bottomLeft.x, bottomRight.x));
    float minY = min(min(topLeft.y, topRight.y), min(bottomLeft.y, bottomRight.y));
    float maxY = max(max(topLeft.y, topRight.y), max(bottomLeft.y, bottomRight.y));
        
    return Rect(minX, minY, (maxX - minX), (maxY - minY));
}

It returns minX and minY instead to get AABB. You can implement the same way without using minX and minY.

#5

thank you for guide .

http://www.jeffreythompson.org/collision-detection/poly-rect.php

this link is very helpful for it.
i got my solution