/**
* Triangulate a polygon by creating edges to a center point.
* 1. If there is a NULL point in the polygon, two triangles are not
* created (these are the two that would have used it)
* 2. THE RETURNED TRIANGLES MUST BE UNREFFED!
*/
static GList*
p2tr_cdt_triangulate_fan (P2trCDT *self,
P2trPoint *center,
GList *edge_pts)
{
GList *new_tris = NULL;
GList *iter;
/* We can not triangulate unless at least two points are given */
if (edge_pts == NULL || edge_pts->next == NULL)
{
p2tr_exception_programmatic ("Not enough points to triangulate as"
" a star!");
}
for (iter = edge_pts; iter != NULL; iter = iter->next)
{
P2trPoint *A = (P2trPoint*) iter->data;
P2trPoint *B = (P2trPoint*) g_list_cyclic_next (edge_pts, iter)->data;
P2trEdge *AB, *BC, *CA;
P2trTriangle *tri;
if (A == NULL || B == NULL)
continue;
AB = p2tr_point_get_edge_to (A, B);
BC = p2tr_mesh_new_or_existing_edge (self->mesh, B, center, FALSE);
CA = p2tr_mesh_new_or_existing_edge (self->mesh, center, A, FALSE);
tri = p2tr_mesh_new_triangle (self->mesh, AB, BC, CA);
new_tris = g_list_prepend (new_tris, tri);
p2tr_edge_unref (BC);
p2tr_edge_unref (CA);
}
return new_tris;
}
/**
* Triangulate a polygon by creating edges to a center point.
* 1. If there is a NULL point in the polygon, two triangles are not
* created (these are the two that would have used it)
* 2. THE RETURNED EDGES MUST BE UNREFFED!
*/
static P2trVEdgeSet*
p2tr_cdt_triangulate_fan (P2trCDT *self,
P2trPoint *center,
GList *edge_pts)
{
P2trVEdgeSet* fan_edges = p2tr_vedge_set_new ();
GList *iter;
/* We can not triangulate unless at least two points are given */
if (edge_pts == NULL || edge_pts->next == NULL)
{
p2tr_exception_programmatic ("Not enough points to triangulate as"
" a star!");
}
for (iter = edge_pts; iter != NULL; iter = iter->next)
{
P2trPoint *A = (P2trPoint*) iter->data;
P2trPoint *B = (P2trPoint*) g_list_cyclic_next (edge_pts, iter)->data;
P2trEdge *AB, *BC, *CA;
if (A == NULL || B == NULL)
continue;
AB = p2tr_point_get_edge_to (A, B, TRUE);
BC = p2tr_mesh_new_or_existing_edge (self->mesh, B, center, FALSE);
CA = p2tr_mesh_new_or_existing_edge (self->mesh, center, A, FALSE);
p2tr_triangle_unref (p2tr_mesh_new_triangle (self->mesh, AB, BC, CA));
p2tr_vedge_set_add (fan_edges, CA);
p2tr_vedge_set_add (fan_edges, BC);
p2tr_vedge_set_add (fan_edges, AB);
}
return fan_edges;
}
