private void update_vertices(Point p) // called after finding a ear from a vertice
{ // removes the vertice from updates_vertices list
ArrayList temp_points = new ArrayList(); // temp. location while updating the list
for (int i = 0; i < updated_vertices.Length; i++) // loop through the list
{
if (p == updated_vertices[i]) // if we found the vertice we'r lookig for
{
mPolygon poly = new mPolygon(updated_vertices);
Point curr_point = p;
Point next_point = poly.get_next_point(p); // find the vertices next neighboor
Point prev_point = poly.get_prev_point(p); // find the vertices previous neighboor
Point[] ear = new Point[3]; // create a 3 point triangle-polygon from these 3 points
ear[0] = prev_point; // previos vertice
ear[1] = curr_point; // current vertice
ear[2] = next_point; // next vertice
ears.Add(ear); // add this ear to ears list
}
else // this is not the vertice we'r looking for
{
temp_points.Add(updated_vertices[i]); // so add it to temp. vertice list
}
}
if ((updated_vertices.Length - temp_points.Count) == 1) // we removed 1 vertice from the list, check the counts
{
updated_vertices = new Point[updated_vertices.Length - 1]; // redimension the list to -1 size, cause we removed 1 vertice
for (int i = 0; i < temp_points.Count; i++)
{
updated_vertices[i] = (Point)temp_points[i]; // update the newest updated_vertices from temp location
}
}
}
private Boolean is_ear(Point p) // checks if given vertice is in a ear
{
mPolygon m = new mPolygon(updated_vertices); // init. a polygon from the current vertices
if (m.is_vertex(p) == true) // if given point is a vertex
{
if (m.vertex_type(p) == VertexType.ConvexPoint) // and it's a convex point
{
Point curr_point = p;
Point prev_point = m.get_prev_point(p); // find previous adjacent point
Point next_point = m.get_next_point(p); // find next adjacent point
for (int i = updated_vertices.GetLowerBound(0); i < updated_vertices.GetUpperBound(0); i++) // loop through all other vertices
{
Point pt = updated_vertices[i];
if (!(is_points_equal(pt, curr_point) || is_points_equal(pt, prev_point) || is_points_equal(pt, next_point)))
{ // if pt is not equal to checked vertice or its's next and prev adjacent vertices
if (is_point_in_triangle(new Point[] { prev_point, curr_point, next_point }, pt)) // check pt lies in triangle
{
return(false); // if another vertice lies in this triangle, then this is not an ear
}
}
}
}
else // concave
{
return(false); // we cannot make ears from concave points
}
return(true); // if CS:IP reaches here, this means vertice passed the test and is an ear
}
return(false); // if the given vertex is not an vertex, it's not related to an ear also!
}