typedef struct {
        float row[3];
        float col[3];
	} triangle;
int triangle_new(triangle *t,int tcolor);   /* input triangle coordinates from mouse */
void triangle_show(triangle *t);
int pt_closest_triangle(float x, float y);
float triangle_area(triangle *t);
int transform_affine(triangle *t);       /* return 0 if not affine */
float pt_pt_distance(float x1, float y1, float x2, float y2);
int triangle_corner(triangle *t, float col, float row);
triangles_limits(float *left,float *up,float *right,float *down);