Detect a point in a triangle in Cocos2d

pointInTriangle.m

// found in http://www.cocos2d-iphone.org/forum/topic/9138

CGFloat GBDot(const CGPoint v1, const CGPoint v2) {
	return v1.x*v2.x + v1.y*v2.y;
}

CGPoint GBSub(const CGPoint v1, const CGPoint v2) {
	return CGPointMake(v1.x - v2.x, v1.y - v2.y);
}

BOOL GBPointInTriangle( CGPoint point, CGPoint pointA, CGPoint pointB, CGPoint pointC ) {
	//http://www.blackpawn.com/texts/pointinpoly/default.html

	CGPoint v0 = GBSub(pointC, pointA);
	CGPoint v1 = GBSub(pointB, pointA);
	CGPoint v2 = GBSub(point, pointA);

	// Compute dot products
	CGFloat dot00 = GBDot(v0, v0);
	CGFloat dot01 = GBDot(v0, v1);
	CGFloat dot02 = GBDot(v0, v2);
	CGFloat dot11 = GBDot(v1, v1);
	CGFloat dot12 = GBDot(v1, v2);

	// Compute barycentric coordinates
	CGFloat invDenom = 1 / (dot00 * dot11 - dot01 * dot01);
	CGFloat u = (dot11 * dot02 - dot01 * dot12) * invDenom;
	CGFloat v = (dot00 * dot12 - dot01 * dot02) * invDenom;

	// Check if point is in triangle
	return (u > 0) && (v > 0) && (u + v < 1);
}