// returns 0 if plane intersects edge,
// -1 if edge is on negative side of plane normal,
// 1 if edge is on positive side of plane normal
int
Bedge::which_side(CWplane& plane) const
{
Wpt p = plane.origin();
Wvec n = plane.normal();
double dot1 = (p - _v1->loc()) * n;
double dot2 = (p - _v2->loc()) * n;
return dot1*dot2 < 1e-20 ? 0 : Sign(dot1);
}
/////////////////////////////////////
// slice_mesh_with_plane()
/////////////////////////////////////
void
HatchingGroupFixed::slice_mesh_with_plane(
Bface *f, CWplane &wpPlane, Wpt_list &wlList)
{
Bface *nxtFace1, *nxtFace2;
Bedge *nxtEdge1, *nxtEdge2;
assert(f->front_facing());
nxtFace1 = f->plane_walk(nullptr,wpPlane,nxtEdge1);
assert(nxtEdge1);
nxtFace2 = f->plane_walk(nxtEdge1,wpPlane,nxtEdge2);
assert(nxtEdge2);
Wpt_list wlList1;
Wpt_list wlList2;
wlList1.push_back(wpPlane.intersect(nxtEdge1->line()));
wlList2.push_back(wpPlane.intersect(nxtEdge2->line()));
//So theres at least 2 pts in the final list...
//sky box fix prevents infinite loops for sky box type geometry
//where the camera is contained inside the object
//points are checked against view volume
while (nxtFace1 && nxtFace1->front_facing()) {
nxtFace1 = nxtFace1->plane_walk(nxtEdge1,wpPlane,nxtEdge1);
if (nxtEdge1) {
Wpt temp_pt = wpPlane.intersect(nxtEdge1->line()); //sky box fix
if (!temp_pt.in_frustum()) {
break;
}
wlList1.push_back(temp_pt);
} else {
cerr << "Slice Mesh :: assert(!nxtFace1)" << endl;
assert(!nxtFace1);
}
}
while (nxtFace2 && nxtFace2->front_facing()) {
nxtFace2 = nxtFace2->plane_walk(nxtEdge2,wpPlane,nxtEdge2);
if (nxtEdge2) {
Wpt temp_pt =wpPlane.intersect(nxtEdge2->line()); //sky box fix
if (!temp_pt.in_frustum()) {
break;
}
wlList2.push_back(temp_pt);
} else {
cerr << "Slice Mesh :: assert(!nxtFace2)" << endl;
assert(!nxtFace2);
}
}
wlList.insert(wlList.end(), wlList1.rbegin(), wlList1.rend());
wlList.insert(wlList.end(), wlList2.begin(), wlList2.end());
}
/////////////////////////////////////
// slice_mesh_with_plane()
/////////////////////////////////////
void
HatchingGroupFixed::slice_mesh_with_plane(
Bface *f, CWplane &wpPlane, Wpt_list &wlList)
{
Bface *nxtFace1, *nxtFace2;
Bedge *nxtEdge1, *nxtEdge2;
assert(f->front_facing());
nxtFace1 = f->plane_walk(0,wpPlane,nxtEdge1);
assert(nxtEdge1);
nxtFace2 = f->plane_walk(nxtEdge1,wpPlane,nxtEdge2);
assert(nxtEdge2);
Wpt_list wlList1;
Wpt_list wlList2;
wlList1 += wpPlane.intersect(nxtEdge1->line());
wlList2 += wpPlane.intersect(nxtEdge2->line());
//So theres at least 2 pts in the final list...
//sky box fix prevents infinite loops for sky box type geometry
//where the camera is contained inside the object
//points are checked against view volume
while (nxtFace1 && (nxtFace1->front_facing())) {
nxtFace1 = nxtFace1->plane_walk(nxtEdge1,wpPlane,nxtEdge1);
if (nxtEdge1) {
Wpt temp_pt = wpPlane.intersect(nxtEdge1->line()); //sky box fix
if (!temp_pt.in_frustum())
{
break;
}
wlList1 += temp_pt;
}
else {
cerr << "Slice Mesh :: assert(!nxtFace1)" << endl;
assert(!nxtFace1);
}
}
while (nxtFace2 && (nxtFace2->front_facing())) {
nxtFace2 = nxtFace2->plane_walk(nxtEdge2,wpPlane,nxtEdge2);
if (nxtEdge2) {
Wpt temp_pt =wpPlane.intersect(nxtEdge2->line()); //sky box fix
if (!temp_pt.in_frustum())
{
break;
}
wlList2 += temp_pt;
}
else {
cerr << "Slice Mesh :: assert(!nxtFace2)" << endl;
assert(!nxtFace2);
}
}
int k;
for (k = wlList1.num()-1; k >= 0; k--) {
wlList += wlList1[k];
}
//wlList += wIsect;
for (k=0; k < wlList2.num(); k++) {
wlList += wlList2[k];
}
}