ready to change coordinates

lines.cpp

@@ -164,6 +164,29 @@ find_longest_line(std::vector<cv::Point> hull, unsigned begin, unsigned end) //t
 	return bestline;
 }
 
+cv::Point
+map_point(double theta, cv::Point origin, cv::Point tomap)
+{
+	//that's the algorithm: res = Rt*(tomap - origin)
+	cv::Vec<double,2> p_as_vector;
+	cv::Point p;
+	cv::Point res;
+	cv::Matx<double,2,2> Rt;
+
+	p = tomap - origin;
+	p_as_vector[0] = p.x;
+	p_as_vector[1] = p.y;
+	//TODO: fai matrice
+	Rt(0,0) = cos(theta);
+	Rt(0,1) = sin(theta);
+	Rt(1,1) = Rt(0,0);
+	Rt(1,0) = -Rt(0,1);
+	cv::Vec<double,2> res_as_vector = Rt*p_as_vector;
+	res.x = res_as_vector[0];
+	res.y = res_as_vector[1];
+	return res;
+}
+
 int main(int argc, char *argv[])
 {
 	char const *fname = "files/masckera.png";
@@ -208,15 +231,20 @@ int main(int argc, char *argv[])
 
 	//these are the "horizontal" lines
 	int *maxdistances = max2_distance(hull);
+	cv::Point corn_1, corn_2, corn_3, corn_4;
+	corn_1 = hull[maxdistances[0]];
+	corn_2 = hull[(maxdistances[0]+1)%hull.size()];
+	corn_3 = hull[maxdistances[1]];
+	corn_4 = hull[(maxdistances[1]+1)%hull.size()];
 
 #ifdef _DEBUG
-	//img = cv::imread(fname,CV_LOAD_IMAGE_COLOR); // uncomment to this to display image with colors
+	img = cv::imread(fname,CV_LOAD_IMAGE_COLOR); // uncomment to this to display image with colors
-	std::cout << "Maxdist1:" << maxdistances[0] << " " << hull[maxdistances[0]] << hull[(maxdistances[0]+1)%hull.size()] << std::endl;
+	std::cout << "Maxdist1:" << maxdistances[0] << " " << corn_1 << corn_2 << std::endl;
-	std::cout << "Maxdist2:" << maxdistances[1] << " " << hull[maxdistances[1]] << hull[(maxdistances[1]+1)%hull.size()] << std::endl;
+	std::cout << "Maxdist2:" << maxdistances[1] << " " << corn_3 << corn_4 << std::endl;
-	cv::circle(img,hull[maxdistances[0]],dotwidth>>2,BROWN,2);
+	cv::circle(img,corn_1,dotwidth>>1,MAGENTA,2);
-	cv::circle(img,hull[(maxdistances[0]+1)%hull.size()],dotwidth>>2,BROWN,2);
+	cv::circle(img,corn_2,dotwidth>>2,MAGENTA,2);
-	cv::circle(img,hull[maxdistances[1]],dotwidth>>2,BROWN,2);
+	cv::circle(img,corn_3,dotwidth>>2,BROWN,2);
-	cv::circle(img,hull[(maxdistances[1]+1)%hull.size()],dotwidth>>2,BROWN,2);
+	cv::circle(img,corn_4,dotwidth>>2,BROWN,2);
 	cv::namedWindow("win", CV_GUI_NORMAL);
 	// cv::imshow("4 corners",img);
 	// cv::waitKey(0);
@@ -249,7 +277,13 @@ int main(int argc, char *argv[])
 	}
 #endif
 
-
+	// theta is the angle of the line connecting point 1 and 2; it will be the
+	// rotation of our new coordinate system
+	double theta = atan(((double)corn_1.y - corn_2.y)/(corn_1.x - corn_2.x));
+	std::cout << "Theta = " << theta << std::endl;
+	assert(map_point(theta, corn_1, corn_1).x == 0);
+	assert(map_point(theta, corn_1, corn_1).y == 0);
+	assert(map_point(theta, corn_1, corn_2).y == 0);
 
 	return EXIT_SUCCESS;
 }