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solvespace/mesh.cpp

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#include "solvespace.h"
void SMesh::Clear(void) {
l.Clear();
}
void SMesh::AddTriangle(STriMeta meta, Vector n, Vector a, Vector b, Vector c) {
Vector ab = b.Minus(a), bc = c.Minus(b);
Vector np = ab.Cross(bc);
if(np.Magnitude() < 1e-10) {
// ugh; gl sometimes tesselates to collinear triangles
return;
}
if(np.Dot(n) > 0) {
AddTriangle(meta, a, b, c);
} else {
AddTriangle(meta, c, b, a);
}
}
void SMesh::AddTriangle(STriMeta meta, Vector a, Vector b, Vector c) {
STriangle t; ZERO(&t);
t.meta = meta;
t.a = a;
t.b = b;
t.c = c;
AddTriangle(&t);
}
void SMesh::AddTriangle(STriangle *st) {
l.Add(st);
}
void SMesh::DoBounding(Vector v, Vector *vmax, Vector *vmin) {
vmax->x = max(vmax->x, v.x);
vmax->y = max(vmax->y, v.y);
vmax->z = max(vmax->z, v.z);
vmin->x = min(vmin->x, v.x);
vmin->y = min(vmin->y, v.y);
vmin->z = min(vmin->z, v.z);
}
void SMesh::GetBounding(Vector *vmax, Vector *vmin) {
int i;
*vmin = Vector::From( 1e12, 1e12, 1e12);
*vmax = Vector::From(-1e12, -1e12, -1e12);
for(i = 0; i < l.n; i++) {
STriangle *st = &(l.elem[i]);
DoBounding(st->a, vmax, vmin);
DoBounding(st->b, vmax, vmin);
DoBounding(st->c, vmax, vmin);
}
}
void SMesh::Simplify(int start) {
int maxTriangles = (l.n - start) + 10;
STriMeta meta = l.elem[start].meta;
STriangle *tout = (STriangle *)AllocTemporary(maxTriangles*sizeof(*tout));
int toutc = 0;
Vector n, *conv = (Vector *)AllocTemporary(maxTriangles*3*sizeof(*conv));
int convc = 0;
int start0 = start;
int i, j;
for(i = start; i < l.n; i++) {
STriangle *tr = &(l.elem[i]);
if(tr->MinAltitude() < LENGTH_EPS) {
tr->tag = 1;
} else {
tr->tag = 0;
}
}
for(;;) {
bool didAdd;
convc = 0;
for(i = start; i < l.n; i++) {
STriangle *tr = &(l.elem[i]);
if(tr->tag) continue;
tr->tag = 1;
n = (tr->Normal()).WithMagnitude(1);
conv[convc++] = tr->a;
conv[convc++] = tr->b;
conv[convc++] = tr->c;
start = i+1;
break;
}
if(i >= l.n) break;
do {
didAdd = false;
for(j = 0; j < convc; j++) {
Vector a = conv[WRAP((j-1), convc)],
b = conv[j],
d = conv[WRAP((j+1), convc)],
e = conv[WRAP((j+2), convc)];
Vector c;
for(i = start; i < l.n; i++) {
STriangle *tr = &(l.elem[i]);
if(tr->tag) continue;
if((tr->a).Equals(d) && (tr->b).Equals(b)) {
c = tr->c;
} else if((tr->b).Equals(d) && (tr->c).Equals(b)) {
c = tr->a;
} else if((tr->c).Equals(d) && (tr->a).Equals(b)) {
c = tr->b;
} else {
continue;
}
// The vertex at C must be convex; but the others must
// be tested
Vector ab = b.Minus(a);
Vector bc = c.Minus(b);
Vector cd = d.Minus(c);
Vector de = e.Minus(d);
double bDot = (ab.Cross(bc)).Dot(n);
double dDot = (cd.Cross(de)).Dot(n);
bDot /= min(ab.Magnitude(), bc.Magnitude());
dDot /= min(cd.Magnitude(), de.Magnitude());
if(fabs(bDot) < LENGTH_EPS && fabs(dDot) < LENGTH_EPS) {
conv[WRAP((j+1), convc)] = c;
// and remove the vertex at j, which is a dup
memmove(conv+j, conv+j+1,
(convc - j - 1)*sizeof(conv[0]));
convc--;
} else if(fabs(bDot) < LENGTH_EPS && dDot > 0) {
conv[j] = c;
} else if(fabs(dDot) < LENGTH_EPS && bDot > 0) {
conv[WRAP((j+1), convc)] = c;
} else if(bDot > 0 && dDot > 0) {
// conv[j] is unchanged, conv[j+1] goes to [j+2]
memmove(conv+j+2, conv+j+1,
(convc - j - 1)*sizeof(conv[0]));
conv[j+1] = c;
convc++;
} else {
continue;
}
didAdd = true;
tr->tag = 1;
break;
}
}
} while(didAdd);
// I need to debug why this is required; sometimes the above code
// still generates a convex polygon
for(i = 0; i < convc; i++) {
Vector a = conv[WRAP((i-1), convc)],
b = conv[i],
c = conv[WRAP((i+1), convc)];
Vector ab = b.Minus(a);
Vector bc = c.Minus(b);
double bDot = (ab.Cross(bc)).Dot(n);
bDot /= min(ab.Magnitude(), bc.Magnitude());
if(bDot < 0) oops();
}
for(i = 0; i < convc - 2; i++) {
STriangle tr = STriangle::From(meta, conv[0], conv[i+1], conv[i+2]);
if(tr.MinAltitude() > LENGTH_EPS) {
tout[toutc++] = tr;
}
}
}
l.n = start0;
for(i = 0; i < toutc; i++) {
AddTriangle(&(tout[i]));
}
FreeTemporary(tout);
FreeTemporary(conv);
}
void SMesh::AddAgainstBsp(SMesh *srcm, SBsp3 *bsp3) {
int i;
for(i = 0; i < srcm->l.n; i++) {
STriangle *st = &(srcm->l.elem[i]);
int pn = l.n;
atLeastOneDiscarded = false;
bsp3->Insert(st, this);
if(!atLeastOneDiscarded && (l.n != (pn+1))) {
l.n = pn;
if(flipNormal) {
AddTriangle(st->meta, st->c, st->b, st->a);
} else {
AddTriangle(st->meta, st->a, st->b, st->c);
}
}
if(l.n - pn > 1) {
Simplify(pn);
}
}
}
void SMesh::MakeFromUnion(SMesh *a, SMesh *b) {
SBsp3 *bspa = SBsp3::FromMesh(a);
SBsp3 *bspb = SBsp3::FromMesh(b);
flipNormal = false;
keepCoplanar = false;
AddAgainstBsp(b, bspa);
flipNormal = false;
keepCoplanar = true;
AddAgainstBsp(a, bspb);
}
void SMesh::MakeFromDifference(SMesh *a, SMesh *b) {
SBsp3 *bspa = SBsp3::FromMesh(a);
SBsp3 *bspb = SBsp3::FromMesh(b);
flipNormal = true;
keepCoplanar = true;
AddAgainstBsp(b, bspa);
flipNormal = false;
keepCoplanar = false;
AddAgainstBsp(a, bspb);
}
bool SMesh::MakeFromInterferenceCheck(SMesh *srca, SMesh *srcb, SMesh *error) {
SBsp3 *bspa = SBsp3::FromMesh(srca);
SBsp3 *bspb = SBsp3::FromMesh(srcb);
error->Clear();
error->flipNormal = true;
error->keepCoplanar = false;
error->AddAgainstBsp(srcb, bspa);
error->AddAgainstBsp(srca, bspb);
// Now we have a list of all the triangles (or fragments thereof) from
// A that lie inside B, or vice versa. That's the interference, and
// we report it so that it can be flagged.
// For the actual output, take the union.
flipNormal = false;
keepCoplanar = false;
AddAgainstBsp(srcb, bspa);
flipNormal = false;
keepCoplanar = true;
AddAgainstBsp(srca, bspb);
// And we're successful if the intersection was empty.
return (error->l.n == 0);
}
void SMesh::MakeFromCopy(SMesh *a) {
int i;
for(i = 0; i < a->l.n; i++) {
AddTriangle(&(a->l.elem[i]));
}
}
DWORD SMesh::FirstIntersectionWith(Point2d mp) {
Vector p0 = Vector::From(mp.x, mp.y, 0);
Vector gn = Vector::From(0, 0, 1);
double maxT = -1e12;
DWORD face = 0;
int i;
for(i = 0; i < l.n; i++) {
STriangle tr = l.elem[i];
tr.a = SS.GW.ProjectPoint3(tr.a);
tr.b = SS.GW.ProjectPoint3(tr.b);
tr.c = SS.GW.ProjectPoint3(tr.c);
Vector n = tr.Normal();
if(n.Dot(gn) < LENGTH_EPS) continue; // back-facing or on edge
if(tr.ContainsPointProjd(gn, p0)) {
// Let our line have the form r(t) = p0 + gn*t
double t = -(n.Dot((tr.a).Minus(p0)))/(n.Dot(gn));
if(t > maxT) {
maxT = t;
face = tr.meta.face;
}
}
}
return face;
}
#define KDTREE_EPS (20*LENGTH_EPS) // nice and sloppy
STriangleLl *STriangleLl::Alloc(void)
{ return (STriangleLl *)AllocTemporary(sizeof(STriangleLl)); }
SKdNode *SKdNode::Alloc(void)
{ return (SKdNode *)AllocTemporary(sizeof(SKdNode)); }
SKdNode *SKdNode::From(SMesh *m) {
int i;
STriangle *tra = (STriangle *)AllocTemporary((m->l.n) * sizeof(*tra));
for(i = 0; i < m->l.n; i++) {
tra[i] = m->l.elem[i];
}
srand(0);
int n = m->l.n;
while(n > 1) {
int k = rand() % n;
n--;
SWAP(STriangle, tra[k], tra[n]);
}
STriangleLl *tll = NULL;
for(i = 0; i < m->l.n; i++) {
STriangleLl *tn = STriangleLl::Alloc();
tn->tri = &(tra[i]);
tn->next = tll;
tll = tn;
}
return SKdNode::From(tll, 0);
}
SKdNode *SKdNode::From(STriangleLl *tll, int which) {
SKdNode *ret = Alloc();
if(!tll) goto leaf;
int i;
int gtc[3] = { 0, 0, 0 }, ltc[3] = { 0, 0, 0 }, allc = 0;
double badness[3];
double split[3];
for(i = 0; i < 3; i++) {
int tcnt = 0;
STriangleLl *ll;
for(ll = tll; ll; ll = ll->next) {
STriangle *tr = ll->tri;
split[i] += (ll->tri->a).Element(i);
split[i] += (ll->tri->b).Element(i);
split[i] += (ll->tri->c).Element(i);
tcnt++;
}
split[i] /= (tcnt*3);
for(ll = tll; ll; ll = ll->next) {
STriangle *tr = ll->tri;
double a = (tr->a).Element(i),
b = (tr->b).Element(i),
c = (tr->c).Element(i);
if(a < split[i] + KDTREE_EPS ||
b < split[i] + KDTREE_EPS ||
c < split[i] + KDTREE_EPS)
{
ltc[i]++;
}
if(a > split[i] - KDTREE_EPS ||
b > split[i] - KDTREE_EPS ||
c > split[i] - KDTREE_EPS)
{
gtc[i]++;
}
if(i == 0) allc++;
}
badness[i] = pow((double)ltc[i], 4) + pow((double)gtc[i], 4);
}
if(badness[0] < badness[1] && badness[0] < badness[2]) {
which = 0;
} else if(badness[1] < badness[2]) {
which = 1;
} else {
which = 2;
}
if(allc < 10) goto leaf;
if(allc == gtc[which] || allc == ltc[which]) goto leaf;
STriangleLl *ll;
STriangleLl *lgt = NULL, *llt = NULL;
for(ll = tll; ll; ll = ll->next) {
STriangle *tr = ll->tri;
double a = (tr->a).Element(which),
b = (tr->b).Element(which),
c = (tr->c).Element(which);
if(a < split[which] + KDTREE_EPS ||
b < split[which] + KDTREE_EPS ||
c < split[which] + KDTREE_EPS)
{
STriangleLl *n = STriangleLl::Alloc();
*n = *ll;
n->next = llt;
llt = n;
}
if(a > split[which] - KDTREE_EPS ||
b > split[which] - KDTREE_EPS ||
c > split[which] - KDTREE_EPS)
{
STriangleLl *n = STriangleLl::Alloc();
*n = *ll;
n->next = lgt;
lgt = n;
}
}
ret->which = which;
ret->c = split[which];
ret->gt = SKdNode::From(lgt, (which + 1) % 3);
ret->lt = SKdNode::From(llt, (which + 1) % 3);
return ret;
leaf:
// dbp("leaf: allc=%d gtc=%d ltc=%d which=%d", allc, gtc[which], ltc[which], which);
ret->tris = tll;
return ret;
}
void SKdNode::ClearTags(void) {
if(gt && lt) {
gt->ClearTags();
lt->ClearTags();
} else {
STriangleLl *ll;
for(ll = tris; ll; ll = ll->next) {
ll->tri->tag = 0;
}
}
}
void SKdNode::AddTriangle(STriangle *tr) {
if(gt && lt) {
double ta = (tr->a).Element(which),
tb = (tr->b).Element(which),
tc = (tr->c).Element(which);
if(ta < c + KDTREE_EPS ||
tb < c + KDTREE_EPS ||
tc < c + KDTREE_EPS)
{
lt->AddTriangle(tr);
}
if(ta > c - KDTREE_EPS ||
tb > c - KDTREE_EPS ||
tc > c - KDTREE_EPS)
{
gt->AddTriangle(tr);
}
} else {
STriangleLl *tn = STriangleLl::Alloc();
tn->tri = tr;
tn->next = tris;
tris = tn;
}
}
void SKdNode::MakeMeshInto(SMesh *m) {
if(gt) gt->MakeMeshInto(m);
if(lt) lt->MakeMeshInto(m);
STriangleLl *ll;
for(ll = tris; ll; ll = ll->next) {
if(ll->tri->tag) continue;
m->AddTriangle(ll->tri);
ll->tri->tag = 1;
}
}
void SKdNode::SnapToVertex(Vector v, SMesh *extras) {
if(gt && lt) {
double vc = v.Element(which);
if(vc < c + KDTREE_EPS) {
lt->SnapToVertex(v, extras);
}
if(vc > c - KDTREE_EPS) {
gt->SnapToVertex(v, extras);
}
// Nothing bad happens if the triangle to be split appears in both
// branches; the first call will split the triangle, so that the
// second call will do nothing, because the modified triangle will
// already contain v
} else {
STriangleLl *ll;
for(ll = tris; ll; ll = ll->next) {
STriangle *tr = ll->tri;
// Do a cheap bbox test first
int k;
bool mightHit = true;
for(k = 0; k < 3; k++) {
if((tr->a).Element(k) < v.Element(k) - KDTREE_EPS &&
(tr->b).Element(k) < v.Element(k) - KDTREE_EPS &&
(tr->c).Element(k) < v.Element(k) - KDTREE_EPS)
{
mightHit = false;
break;
}
if((tr->a).Element(k) > v.Element(k) + KDTREE_EPS &&
(tr->b).Element(k) > v.Element(k) + KDTREE_EPS &&
(tr->c).Element(k) > v.Element(k) + KDTREE_EPS)
{
mightHit = false;
break;
}
}
if(!mightHit) continue;
if(tr->a.Equals(v)) { tr->a = v; continue; }
if(tr->b.Equals(v)) { tr->b = v; continue; }
if(tr->c.Equals(v)) { tr->c = v; continue; }
if(v.OnLineSegment(tr->a, tr->b)) {
STriangle nt = STriangle::From(tr->meta, tr->a, v, tr->c);
extras->AddTriangle(&nt);
tr->a = v;
continue;
}
if(v.OnLineSegment(tr->b, tr->c)) {
STriangle nt = STriangle::From(tr->meta, tr->b, v, tr->a);
extras->AddTriangle(&nt);
tr->b = v;
continue;
}
if(v.OnLineSegment(tr->c, tr->a)) {
STriangle nt = STriangle::From(tr->meta, tr->c, v, tr->b);
extras->AddTriangle(&nt);
tr->c = v;
continue;
}
}
}
}
void SKdNode::SnapToMesh(SMesh *m) {
int i, j, k;
for(i = 0; i < m->l.n; i++) {
STriangle *tr = &(m->l.elem[i]);
for(j = 0; j < 3; j++) {
Vector v = ((j == 0) ? tr->a :
((j == 1) ? tr->b :
tr->c));
SMesh extra;
ZERO(&extra);
SnapToVertex(v, &extra);
for(k = 0; k < extra.l.n; k++) {
STriangle *tra = (STriangle *)AllocTemporary(sizeof(*tra));
*tra = extra.l.elem[k];
AddTriangle(tra);
}
extra.Clear();
}
}
}
void SKdNode::FindEdgeOn(Vector a, Vector b, int *n, int *nOther,
STriMeta m, int cnt)
{
if(gt && lt) {
double ac = a.Element(which),
bc = b.Element(which);
if(ac < c + KDTREE_EPS ||
bc < c + KDTREE_EPS)
{
lt->FindEdgeOn(a, b, n, nOther, m, cnt);
}
if(ac > c - KDTREE_EPS ||
bc > c - KDTREE_EPS)
{
gt->FindEdgeOn(a, b, n, nOther, m, cnt);
}
} else {
STriangleLl *ll;
for(ll = tris; ll; ll = ll->next) {
STriangle *tr = ll->tri;
if(tr->tag == cnt) continue;
if((a.EqualsExactly(tr->b) && b.EqualsExactly(tr->a)) ||
(a.EqualsExactly(tr->c) && b.EqualsExactly(tr->b)) ||
(a.EqualsExactly(tr->a) && b.EqualsExactly(tr->c)))
{
(*n)++;
if(tr->meta.face != m.face) (*nOther)++;
}
tr->tag = cnt;
}
}
}
void SKdNode::MakeCertainEdgesInto(SEdgeList *sel, bool emphasized) {
SMesh m;
ZERO(&m);
ClearTags();
MakeMeshInto(&m);
int cnt = 1234;
int i, j;
for(i = 0; i < m.l.n; i++) {
STriangle *tr = &(m.l.elem[i]);
for(j = 0; j < 3; j++) {
Vector a = (j == 0) ? tr->a : ((j == 1) ? tr->b : tr->c);
Vector b = (j == 0) ? tr->b : ((j == 1) ? tr->c : tr->a);
int n = 0, nOther = 0;
FindEdgeOn(a, b, &n, &nOther, tr->meta, cnt++);
if(n != 1) {
if(!emphasized) {
if(n == 0) sel->AddEdge(a, b);
} else {
dbp("hanging: n=%d (%.3f %.3f %.3f) (%.3f %.3f %.3f)",
n, CO(a), CO(b));
}
}
if(nOther > 0) {
if(emphasized) sel->AddEdge(a, b);
}
}
}
m.Clear();
}
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