/**
* gts_triangle_is_stabbed:
* @t: a #GtsTriangle.
* @p: a #GtsPoint.
* @orientation: a pointer or %NULL.
*
* Returns: one of the vertices of @t, one of the edges of @t or @t if
* any of these are stabbed by the ray starting at @p (included) and
* ending at (@p->x, @p->y, +infty), %NULL otherwise. If the ray is
* contained in the plane of the triangle %NULL is also returned. If
* @orientation is not %NULL, it is set to the value of the
* orientation of @p relative to @t (as given by
* gts_point_orientation_3d()).
*/
GtsObject * gts_triangle_is_stabbed (GtsTriangle * t,
GtsPoint * p,
gdouble * orientation)
{
GtsVertex * v1, * v2, * v3, * inverted = NULL;
GtsEdge * e1, * e2, * e3, * tmp;
gdouble o, o1, o2, o3;
g_return_val_if_fail (t != NULL, NULL);
g_return_val_if_fail (p != NULL, NULL);
gts_triangle_vertices_edges (t, NULL, &v1, &v2, &v3, &e1, &e2, &e3);
o = gts_point_orientation (GTS_POINT (v1), GTS_POINT (v2), GTS_POINT (v3));
if (o == 0.)
return NULL;
if (o < 0.) {
inverted = v1;
v1 = v2;
v2 = inverted;
tmp = e2;
e2 = e3;
e3 = tmp;
}
o = gts_point_orientation_3d (GTS_POINT (v1),
GTS_POINT (v2),
GTS_POINT (v3),
p);
if (o < 0.)
return NULL;
o1 = gts_point_orientation (GTS_POINT (v1), GTS_POINT (v2), p);
if (o1 < 0.)
return NULL;
o2 = gts_point_orientation (GTS_POINT (v2), GTS_POINT (v3), p);
if (o2 < 0.)
return NULL;
o3 = gts_point_orientation (GTS_POINT (v3), GTS_POINT (v1), p);
if (o3 < 0.)
return NULL;
if (orientation) *orientation = inverted ? -o : o;
if (o1 == 0.) {
if (o2 == 0.)
return GTS_OBJECT (v2);
if (o3 == 0.)
return GTS_OBJECT (v1);
return GTS_OBJECT (e1);
}
if (o2 == 0.) {
if (o3 == 0.)
return GTS_OBJECT (v3);
return GTS_OBJECT (e2);
}
if (o3 == 0.)
return GTS_OBJECT (e3);
return GTS_OBJECT (t);
}
/**
* gts_triangle_orientation:
* @t: a #GtsTriangle.
*
* Checks for the orientation of the plane (x,y) projection of a
* triangle. See gts_point_orientation() for details. This function
* is geometrically robust.
*
* Returns: a number depending on the orientation of the vertices of @t.
*/
gdouble gts_triangle_orientation (GtsTriangle * t)
{
GtsVertex * v1, * v2 = NULL, * v3 = NULL;
g_return_val_if_fail (t != NULL, 0.0);
v1 = GTS_SEGMENT (t->e1)->v1;
if (GTS_SEGMENT (t->e1)->v1 == GTS_SEGMENT (t->e2)->v1) {
v2 = GTS_SEGMENT (t->e2)->v2;
v3 = GTS_SEGMENT (t->e1)->v2;
}
else if (GTS_SEGMENT (t->e1)->v2 == GTS_SEGMENT (t->e2)->v2) {
v2 = GTS_SEGMENT (t->e1)->v2;
v3 = GTS_SEGMENT (t->e2)->v1;
}
else if (GTS_SEGMENT (t->e1)->v1 == GTS_SEGMENT (t->e2)->v2) {
v2 = GTS_SEGMENT (t->e2)->v1;
v3 = GTS_SEGMENT (t->e1)->v2;
}
else if (GTS_SEGMENT (t->e1)->v2 == GTS_SEGMENT (t->e2)->v1) {
v2 = GTS_SEGMENT (t->e1)->v2;
v3 = GTS_SEGMENT (t->e2)->v2;
}
else
g_assert_not_reached ();
return gts_point_orientation (GTS_POINT (v1),
GTS_POINT (v2),
GTS_POINT (v3));
}
/**
* gts_segments_are_intersecting:
* @s1: a #GtsSegment.
* @s2: a #GtsSegment.
*
* Returns: %GTS_IN if @s1 and @s2 are intersecting, %GTS_ON if one of the
* endpoints of @s1 (resp. @s2) lies on @s2 (resp. @s1), %GTS_OUT otherwise.
*/
GtsIntersect gts_segments_are_intersecting (GtsSegment * s1, GtsSegment * s2)
{
GtsPoint * p1, * p2, * p3, * p4;
gdouble d1, d2, d3, d4;
g_return_val_if_fail (s1 != NULL && s2 != NULL, FALSE);
p1 = GTS_POINT (s1->v1); p2 = GTS_POINT (s1->v2);
p3 = GTS_POINT (s2->v1); p4 = GTS_POINT (s2->v2);
d1 = gts_point_orientation (p1, p2, p3);
d2 = gts_point_orientation (p1, p2, p4);
if ((d1 > 0.0 && d2 > 0.0) ||
(d1 < 0.0 && d2 < 0.0))
return GTS_OUT;
d3 = gts_point_orientation (p3, p4, p1);
d4 = gts_point_orientation (p3, p4, p2);
if ((d3 > 0.0 && d4 > 0.0) ||
(d3 < 0.0 && d4 < 0.0))
return GTS_OUT;
if (d1 == 0.0 || d2 == 0.0 || d3 == 0.0 || d4 == 0.0)
return GTS_ON;
return GTS_IN;
}
static void gts_constraint_split (GtsConstraint * c,
GtsSurface * s,
GtsFifo * fifo)
{
GSList * i;
GtsVertex * v1, * v2;
GtsEdge * e;
g_return_if_fail (c != NULL);
g_return_if_fail (s != NULL);
v1 = GTS_SEGMENT (c)->v1;
v2 = GTS_SEGMENT (c)->v2;
e = GTS_EDGE (c);
i = e->triangles;
while (i) {
GtsFace * f = i->data;
if (GTS_IS_FACE (f) && gts_face_has_parent_surface (f, s)) {
GtsVertex * v = gts_triangle_vertex_opposite (GTS_TRIANGLE (f), e);
if (gts_point_orientation (GTS_POINT (v1),
GTS_POINT (v2),
GTS_POINT (v)) == 0.) {
GSList * j = e->triangles;
GtsFace * f1 = NULL;
GtsEdge * e1, * e2;
/* replaces edges with constraints */
gts_triangle_vertices_edges (GTS_TRIANGLE (f), e,
&v1, &v2, &v, &e, &e1, &e2);
if (!GTS_IS_CONSTRAINT (e1)) {
GtsEdge * ne1 =
gts_edge_new (GTS_EDGE_CLASS (GTS_OBJECT (c)->klass), v2, v);
gts_edge_replace (e1, ne1);
gts_object_destroy (GTS_OBJECT (e1));
e1 = ne1;
if (fifo) gts_fifo_push (fifo, e1);
}
if (!GTS_IS_CONSTRAINT (e2)) {
GtsEdge * ne2 =
gts_edge_new (GTS_EDGE_CLASS (GTS_OBJECT (c)->klass), v, v1);
gts_edge_replace (e2, ne2);
gts_object_destroy (GTS_OBJECT (e2));
e2 = ne2;
if (fifo) gts_fifo_push (fifo, e2);
}
/* look for face opposite */
while (j && !f1) {
if (GTS_IS_FACE (j->data) &&
gts_face_has_parent_surface (j->data, s))
f1 = j->data;
j = j->next;
}
if (f1) { /* c is not a boundary of s */
GtsEdge * e3, * e4, * e5;
GtsVertex * v3;
gts_triangle_vertices_edges (GTS_TRIANGLE (f1), e,
&v1, &v2, &v3, &e, &e3, &e4);
e5 = gts_edge_new (s->edge_class, v, v3);
gts_surface_add_face (s, gts_face_new (s->face_class, e5, e2, e3));
gts_surface_add_face (s, gts_face_new (s->face_class, e5, e4, e1));
gts_object_destroy (GTS_OBJECT (f1));
}
gts_object_destroy (GTS_OBJECT (f));
return;
}
}
i = i->next;
}
}
