+// in x1,y1 x2,y1 out x1,y1 x2,y2
+// x1,y2 x2,y2 x3,y3 x4,y4
+ void set_matrix(double in_x1, double in_y1, double in_x2, double in_y2,
+ double out_x1, double out_y1, double out_x2, double out_y2,
+ double out_x3, double out_y3, double out_x4, double out_y4);