bool Collision::PixelPerfectTest(const sf::Sprite& Object1, const sf::Sprite& Object2, sf::Uint8 AlphaLimit) {
//Get AABBs of the two sprites
sf::IntRect Object1AABB = GetAABB(Object1);
sf::IntRect Object2AABB = GetAABB(Object2);
sf::IntRect Intersection;
if (Object1AABB.Intersects(Object2AABB, &Intersection)) {
//We've got an intersection we need to process the pixels
//In that Rect.
//Bail out now if AlphaLimit = 0
if (AlphaLimit == 0) return true;
//There are a few hacks here, sometimes the TransformToLocal returns negative points
//Or Points outside the image. We need to check for these as they print to the error console
//which is slow, and then return black which registers as a hit.
sf::IntRect O1SubRect = Object1.GetSubRect();
sf::IntRect O2SubRect = Object2.GetSubRect();
sf::Vector2i O1SubRectSize(O1SubRect.GetWidth(), O1SubRect.GetHeight());
sf::Vector2i O2SubRectSize(O2SubRect.GetWidth(), O2SubRect.GetHeight());
sf::Vector2f o1v;
sf::Vector2f o2v;
//Loop through our pixels
for (int i = Intersection.Left; i < Intersection.Right; i++) {
for (int j = Intersection.Top; j < Intersection.Bottom; j++) {
o1v = Object1.TransformToLocal(sf::Vector2f(i, j)); //Creating Objects each loop :(
o2v = Object2.TransformToLocal(sf::Vector2f(i, j));
//Hack to make sure pixels fall withint the Sprite's Image
if (o1v.x > 0 && o1v.y > 0 && o2v.x > 0 && o2v.y > 0 &&
o1v.x < O1SubRectSize.x && o1v.y < O1SubRectSize.y &&
o2v.x < O2SubRectSize.x && o2v.y < O2SubRectSize.y) {
//If both sprites have opaque pixels at the same point we've got a hit
if ((Object1.GetPixel(static_cast<int> (o1v.x), static_cast<int> (o1v.y)).a > AlphaLimit) &&
(Object2.GetPixel(static_cast<int> (o2v.x), static_cast<int> (o2v.y)).a > AlphaLimit)) {
return true;
}
}
}
}
return false;
}
return false;
}
