static void smooth_vertex (GtsVertex * v, gpointer * data)
{
GtsSurface * s = data[0];
if (!gts_vertex_is_boundary (v, s)) {
gdouble * lambda = data[1];
GSList * vertices = gts_vertex_neighbors (v, NULL, s);
GSList * i;
GtsVector U0 = { 0., 0., 0.};
guint n = 0;
i = vertices;
while (i) {
GtsPoint * p = i->data;
U0[0] += p->x;
U0[1] += p->y;
U0[2] += p->z;
n++;
i = i->next;
}
g_slist_free (vertices);
if (n > 0) {
GTS_POINT (v)->x += (*lambda)*(U0[0]/n - GTS_POINT (v)->x);
GTS_POINT (v)->y += (*lambda)*(U0[1]/n - GTS_POINT (v)->y);
GTS_POINT (v)->z += (*lambda)*(U0[2]/n - GTS_POINT (v)->z);
}
}
}
static PyObject*
is_boundary(PygtsVertex* self, PyObject *args)
{
PyObject *s_;
PygtsObject *s;
SELF_CHECK
/* Parse the args */
if(! PyArg_ParseTuple(args, "O", &s_) ) {
return NULL;
}
/* Convert to PygtsObjects */
if(!pygts_surface_check(s_)) {
PyErr_SetString(PyExc_TypeError,"expected a Surface");
return NULL;
}
s = PYGTS_OBJECT(s_);
if( gts_vertex_is_boundary(PYGTS_VERTEX_AS_GTS_VERTEX(self),
PYGTS_SURFACE_AS_GTS_SURFACE(s)) ) {
Py_INCREF(Py_True);
return Py_True;
}
else {
Py_INCREF(Py_False);
return Py_False;
}
}
/**
* gts_vertex_gaussian_curvature:
* @v: a #GtsVertex.
* @s: a #GtsSurface.
* @Kg: the Discrete Gaussian Curvature approximation at @v.
*
* Computes the Discrete Gaussian Curvature approximation at @v.
*
* This approximation is from the paper:
* Discrete Differential-Geometry Operators for Triangulated 2-Manifolds
* Mark Meyer, Mathieu Desbrun, Peter Schroder, Alan H. Barr
* VisMath '02, Berlin (Germany)
* http://www-grail.usc.edu/pubs.html
*
* Returns: %TRUE if the operator could be evaluated, %FALSE if the
* evaluation failed for some reason (@v is boundary or is the
* endpoint of a non-manifold edge.)
*/
gboolean gts_vertex_gaussian_curvature (GtsVertex * v, GtsSurface * s,
gdouble * Kg)
{
GSList * faces, * edges, * i;
gdouble area = 0.0;
gdouble angle_sum = 0.0;
g_return_val_if_fail (v != NULL, FALSE);
g_return_val_if_fail (s != NULL, FALSE);
g_return_val_if_fail (Kg != NULL, FALSE);
/* this operator is not defined for boundary edges */
if (gts_vertex_is_boundary (v, s)) return (FALSE);
faces = gts_vertex_faces (v, s, NULL);
g_return_val_if_fail (faces != NULL, FALSE);
edges = gts_vertex_fan_oriented (v, s);
if (edges == NULL) {
g_slist_free (faces);
return (FALSE);
}
i = faces;
while (i) {
GtsFace * f = i->data;
area += region_area (v, f);
i = i->next;
}
g_slist_free (faces);
i = edges;
while (i) {
GtsEdge * e = i->data;
GtsVertex * v1 = GTS_SEGMENT (e)->v1;
GtsVertex * v2 = GTS_SEGMENT (e)->v2;
angle_sum += angle_from_cotan (v, v1, v2);
i = i->next;
}
g_slist_free (edges);
*Kg = (2.0*M_PI - angle_sum)/area;
return TRUE;
}
/**
* gts_vertex_mean_curvature_normal:
* @v: a #GtsVertex.
* @s: a #GtsSurface.
* @Kh: the Mean Curvature Normal at @v.
*
* Computes the Discrete Mean Curvature Normal approximation at @v.
* The mean curvature at @v is half the magnitude of the vector @Kh.
*
* Note: the normal computed is not unit length, and may point either
* into or out of the surface, depending on the curvature at @v. It
* is the responsibility of the caller of the function to use the mean
* curvature normal appropriately.
*
* This approximation is from the paper:
* Discrete Differential-Geometry Operators for Triangulated 2-Manifolds
* Mark Meyer, Mathieu Desbrun, Peter Schroder, Alan H. Barr
* VisMath '02, Berlin (Germany)
* http://www-grail.usc.edu/pubs.html
*
* Returns: %TRUE if the operator could be evaluated, %FALSE if the
* evaluation failed for some reason (@v is boundary or is the
* endpoint of a non-manifold edge.)
*/
gboolean gts_vertex_mean_curvature_normal (GtsVertex * v, GtsSurface * s,
GtsVector Kh)
{
GSList * faces, * edges, * i;
gdouble area = 0.0;
g_return_val_if_fail (v != NULL, FALSE);
g_return_val_if_fail (s != NULL, FALSE);
/* this operator is not defined for boundary edges */
if (gts_vertex_is_boundary (v, s)) return (FALSE);
faces = gts_vertex_faces (v, s, NULL);
g_return_val_if_fail (faces != NULL, FALSE);
edges = gts_vertex_fan_oriented (v, s);
if (edges == NULL) {
g_slist_free (faces);
return (FALSE);
}
i = faces;
while (i) {
GtsFace * f = i->data;
area += region_area (v, f);
i = i->next;
}
g_slist_free (faces);
Kh[0] = Kh[1] = Kh[2] = 0.0;
i = edges;
while (i) {
GtsEdge * e = i->data;
GtsVertex * v1 = GTS_SEGMENT (e)->v1;
GtsVertex * v2 = GTS_SEGMENT (e)->v2;
gdouble temp;
temp = cotan (v1, v, v2);
Kh[0] += temp*(GTS_POINT (v2)->x - GTS_POINT (v)->x);
Kh[1] += temp*(GTS_POINT (v2)->y - GTS_POINT (v)->y);
Kh[2] += temp*(GTS_POINT (v2)->z - GTS_POINT (v)->z);
temp = cotan (v2, v, v1);
Kh[0] += temp*(GTS_POINT (v1)->x - GTS_POINT (v)->x);
Kh[1] += temp*(GTS_POINT (v1)->y - GTS_POINT (v)->y);
Kh[2] += temp*(GTS_POINT (v1)->z - GTS_POINT (v)->z);
i = i->next;
}
g_slist_free (edges);
if (area > 0.0) {
Kh[0] /= 2*area;
Kh[1] /= 2*area;
Kh[2] /= 2*area;
} else {
return (FALSE);
}
return TRUE;
}
