学步园

bool pt_in_positive(CvPoint pt,CvPoint input_pt1,CvPoint input_pt2)
{
	double A,B,C;
	double k_t;
	k_t=input_pt2.x - input_pt1.x;
	if (k_t==0.)
	{
		A=1;
		B=0;
		C=input_pt1.x;
	}
	else
	{
		double k,b;
		k=((double)input_pt2.y - input_pt1.y) /(input_pt2.x - input_pt1.x);
		b=input_pt1.y - k*input_pt1.x; 
		A=k;
		B=-1;
		C=b;
	}
	if (A*pt.x+B*pt.y+C>0)
		return true;
	else
		return false;	
}