static void FaceEdgeSplicer(Face & face,int vi0,BSPNode *n)
{
// the face's edge starting from vertex vi0 is sliced by any incident hypeplane in the bsp
if(n->isleaf) return;
int vi1 = (vi0+1)%face.vertex.size();
float3 v0 = face.vertex[vi0];
float3 v1 = face.vertex[vi1];
assert(magnitude(v0-v1) > QUANTIZEDCHECK );
int f0 = PlaneTest(float4(n->xyz(), n->w), v0);
int f1 = PlaneTest(float4(n->xyz(), n->w), v1);
if(f0==COPLANAR && f1== COPLANAR)
{
// have to pass down both sides, but we have to make sure we do all subsegments generated by the first side
int count = face.vertex.size();
FaceEdgeSplicer(face,vi0,n->under.get());
int k=vi0 + (face.vertex.size()-count);
while(k>=vi0)
{
FaceEdgeSplicer(face,k,n->over.get());
k--;
}
}
else if((f0|f1) == UNDER)
{
FaceEdgeSplicer(face,vi0,n->under.get());
}
else if((f0|f1) == OVER)
{
FaceEdgeSplicer(face,vi0,n->over.get());
}
else
{
edgesplitcount++;
assert(magnitude(v0-v1) > QUANTIZEDCHECK);
assert((f0|f1) == SPLIT);
float3 vmid = PlaneLineIntersection(*n,v0,v1);
assert(magnitude(vmid-v1) > QUANTIZEDCHECK);
assert(magnitude(v0-vmid) > QUANTIZEDCHECK);
int fmid = PlaneTest(float4(n->xyz(), n->w), vmid);
assert(fmid==0);
face.vertex.insert(face.vertex.begin() + vi0 + 1, vmid); // Insert(face.vertex, vmid, vi0 + 1);
if(f0==UNDER)
{
FaceEdgeSplicer(face,vi0+1,n->over.get());
FaceEdgeSplicer(face,vi0 ,n->under.get());
}
else
{
assert(f0==OVER);
FaceEdgeSplicer(face,vi0+1,n->under.get());
FaceEdgeSplicer(face,vi0 ,n->over.get());
}
}
}
btScalar DistanceBetweenLines(const btVector3 &ustart, const btVector3 &udir, const btVector3 &vstart, const btVector3 &vdir, btVector3 *upoint, btVector3 *vpoint)
{
static btVector3 cp;
cp = cross(udir,vdir).normalized();
btScalar distu = -dot(cp,ustart);
btScalar distv = -dot(cp,vstart);
btScalar dist = (btScalar)fabs(distu-distv);
if(upoint)
{
btPlane plane;
plane.normal = cross(vdir,cp).normalized();
plane.dist = -dot(plane.normal,vstart);
*upoint = PlaneLineIntersection(plane,ustart,ustart+udir);
}
if(vpoint)
{
btPlane plane;
plane.normal = cross(udir,cp).normalized();
plane.dist = -dot(plane.normal,ustart);
*vpoint = PlaneLineIntersection(plane,vstart,vstart+vdir);
}
return dist;
}
void FaceSlice(Face & face,const float4 &clip) {
int count=0;
for(unsigned int i=0;i<face.vertex.size();i++) {
unsigned int i2=(i+1)%face.vertex.size();
int vf0 = PlaneTest(clip, face.vertex[i]);
int vf2 = PlaneTest(clip, face.vertex[i2]);
if((vf0==OVER && vf2==UNDER)||
(vf0==UNDER && vf2==OVER ) )
{
float3 vmid;
vmid = PlaneLineIntersection(clip,face.vertex[i],face.vertex[i2]);
assert(!PlaneTest(clip, vmid));
face.vertex.insert(face.vertex.begin() + i2, vmid); // Insert(face.vertex, vmid, i2);
i=0;
assert(count<2);
count++;
}
}
}
static void BSPClipFace(BSPNode *n,Face && face,const float3 &position,std::vector<Face> &under,std::vector<Face> &over)
{
if(n->isleaf==UNDER)
{
under.push_back(face);
return;
}
if(n->isleaf==OVER)
{
over.push_back(face);
return;
}
float4 plane(n->xyz(), n->w + dot(position, n->xyz()));
int flag = FaceSplitTest(face, plane);
if(flag == UNDER) {
return BSPClipFace(n->under.get(),std::move(face),position,under,over);
}
if(flag == OVER) {
return BSPClipFace(n->over.get(),std::move(face),position,under,over);
}
if(flag==COPLANAR)
{
return BSPClipFace(dot(n->xyz(), face.xyz()) > 0 ? n->under.get() : n->over.get(), std::move(face), position, under, over);
}
assert(flag==SPLIT);
Face funder, fover;
fover.xyz() = funder.xyz() = face.xyz();
fover.w = funder.w = face.w;
fover.gu = funder.gu = face.gu;
fover.gv = funder.gv = face.gv;
fover.ot = funder.ot = face.ot;
fover.matid= funder.matid= face.matid;
for(unsigned int i=0;i<face.vertex.size();i++){
float3& vi = face.vertex[i];
float3& vi1= face.vertex[(i+1)%face.vertex.size()];
int vf = PlaneTest(float4(plane.xyz(), plane.w), vi);
int vf1 = PlaneTest(float4(plane.xyz(), plane.w), vi1);
if(vf==COPLANAR)
{
funder.vertex.push_back(vi);
fover.vertex.push_back(vi);
continue; // possible loop optimization
}
else if(vf==UNDER)
{
funder.vertex.push_back(vi);
}
else
{
assert(vf==OVER);
fover.vertex.push_back(vi);
}
if(vf != vf1 && vf !=COPLANAR && vf1 != COPLANAR)
{
float3 vmid = PlaneLineIntersection(plane.xyz(), plane.w, vi, vi1);
funder.vertex.push_back(vmid);
fover.vertex.push_back(vmid);
}
}
BSPClipFace(n->under.get(),std::move(funder),position,under,over);
BSPClipFace(n->over.get() ,std::move(fover) ,position,under,over);
}
