/**********************************************************************
* TriStrip:
**********************************************************************/
Bface*
TriStrip::backup_strip(Bface* f, Bvert*& a)
{
// we'd like to draw a triangle strip starting at the
// given triangle and proceeding "forward." but to get
// the most bang for the buck, we'll first "backup" over
// as many triangles as possible to find a starting place
// from which we can generate a longer strip.
assert(!f->flag());
mark_face(f);
Bface* ret = f;
Bvert* b = f->next_vert_ccw(a);
Bedge* e;
int i = 0;
while((e = f->edge_from_vert((i%2) ? b : a)) &&
e->consistent_orientation() &&
e->is_crossable() &&
(f = e->other_face(f)) &&
is_cleared(f)) {
mark_face(f);
ret = f;
Bvert* d = f->other_vertex(a,b);
b = a;
a = d;
i++;
}
_orientation = ((i%2) != 0);
return ret;
}
CWvec&
Bface::vert_normal(CBvert* v, Wvec& n) const
{
// for gouraud shading: return appropriate
// normal to use at a vertex of this face
assert(this->contains(v));
if(!v->is_crease()) {
n = v->norm();
return n;
}
// take average of face normals in star of v,
// using faces which can be reached from this
// face without crossing a crease edge
n = weighted_vnorm(this, v); // add weighted normal from this face
int count = 1; // count of faces processed
// wind around v in clockwise direction
// but don't cross a crease edge
CBface* f = this;
Bedge* e = edge_from_vert(v);
for (; e&&!e->is_crease() && (f=e->other_face(f)); e=f->edge_from_vert(v)) {
n += weighted_vnorm(f, v);
if (++count > v->degree()) {
// this should never happen, but it does
// happen on effed up models
// (i.e. when "3rd faces" get added)
break;
}
}
// wind around v in counter-clockwise direction;
// as before, don't cross a crease edge
f = this;
e = edge_before_vert(v);
for(; e&&!e->is_crease()&&(f=e->other_face(f)); e=f->edge_before_vert(v)) {
n += weighted_vnorm(f, v);
if(++count > v->degree())
break;
}
n = n.normalized();
return n;
}
bool
Bface::local_search(
Bsimplex *&end,
Wvec &final_bc,
CWpt &target,
Wpt &reached,
Bsimplex *repeater,
int iters)
{
// this is a hack to prevent recursion that goes too deep.
// however if that is a problem the real cause should be
// tracked down and fixed.
if (iters <= 0)
return 0;
Wvec bc;
bool is_on_tri = 0;
Wpt nearpt = nearest_pt(target, bc, is_on_tri);
Bsimplex* sim = bc2sim(bc);
if (!is_on_tri) {
if (sim == repeater) // We hit a loop in the recursion, so stop
return 0;
if (sim != this) { // We're on the boundary of the face
if (is_edge(sim)) {
Bedge* e = (Bedge*)sim;
// Can't cross a border
if (!e->is_border()) {
// recurse starting from the other face.
int good_path = e->other_face(this)->local_search(
end, final_bc, target, reached, sim, iters-1);
if (good_path == 1)
return 1;
else if (good_path == -1)
return repeater ? true : false; // XXX - changed from -1 : 0 -- should check
}
else {
return repeater ? true : false; // XXX - changed from -1 : 0 -- should check
}
} else {
// Try to follow across a vertex
Bface_list near_faces(16);
assert(is_vert(sim));
((Bvert*)sim)->get_faces(near_faces);
for (int k = near_faces.size()-1; k>=0; k--) {
if (near_faces[k] != this) {
int good_path = near_faces[k]->local_search(
end, final_bc, target, reached, sim, iters-1);
if (good_path == 1)
return 1;
else if (good_path==-1)
return repeater ? true : false; // XXX - changed from -1 : 0 -- should check
}
}
}
}
}
reached = nearpt;
end = this;
final_bc = bc;
return 1;
}
Bsimplex*
Bface::ndc_walk(
CNDCpt& target,
CWvec &passed_bc,
CNDCpt &nearest,
int is_on_tri,
bool use_passed_in_params) const
{
// just like local_search, but in NDC space
//
// start from this face, move in NDC space
// across the mesh to reach the target
//
// if reached, return the simplex that contains
// the target point.
// we only move if it will get us closer to the goal. Hence, we
// can never wander off forever.
// if can't reach it, return 0
NDCpt y (nearest);
Wvec bc(passed_bc);
if (!use_passed_in_params) {
y = nearest_pt_ndc(target, bc, is_on_tri);
}
Bsimplex* sim = bc2sim(bc);
if (is_on_tri) {
// target is on this triangle
// return the lowest-dimensional
// simplex on which it lies
return sim;
}
if (is_edge(sim)) {
Bedge* e = (Bedge*)sim;
Bface* f = e->is_sil() ? nullptr : e->other_face(this);
if (f) {
Wvec new_bc;
int new_on_tri;
NDCpt new_best = f->nearest_pt_ndc(target, new_bc, new_on_tri);
if (new_best.dist_sqrd(target) < y.dist_sqrd(target))
return f->ndc_walk(target, new_bc, new_best, new_on_tri, true);
else
return nullptr;
} else {
return nullptr;
}
}
// better be a vertex
assert(is_vert(sim));
Bvert* v = (Bvert*)sim;
if (v->degree(SilEdgeFilter()) > 0)
return nullptr;
Bface_list nbrs(16);
((Bvert*)sim)->get_faces(nbrs);
double dist_sqrd = 1e50;
Bface* best = nullptr;
Wvec best_bc;
NDCpt best_nearest;
int best_on_tri = 0;
Wvec curr_bc;
NDCpt curr_nearest;
int curr_on_tri=0;
for (Bface_list::size_type k = 0; k < nbrs.size(); k++) {
if (nbrs[k] != this) {
curr_nearest = nbrs[k]->nearest_pt_ndc(target, curr_bc, curr_on_tri);
if (curr_nearest.dist_sqrd(target) < dist_sqrd ) {
dist_sqrd = curr_nearest.dist_sqrd(target);
best_bc = curr_bc;
best_on_tri = curr_on_tri;
best_nearest = curr_nearest;
best = nbrs[k];
}
}
}
if (dist_sqrd < y.dist_sqrd(target)) {
return best->ndc_walk(target, best_bc, best_nearest, best_on_tri, true);
}
return nullptr;
}
