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222007f3d8
solvespace/bsp.cpp
Jonathan Westhues cad77c9c47 Add routines to remove T intersections from the mesh, which are 
introduced by the bsp routines. It's usually, though not always,
possible to generate a watertight mesh. The occasions where it's
not look ugly, floating point issues, no quick fix.

And use those to generate a list of edges where two different faces
meet, which I can emphasize for cosmetic reasons (and some UI to
specify whether to do that, and with what color).

And make the right mouse button rotate the model, since that was
previously doing nothing.

[git-p4: depot-paths = "//depot/solvespace/": change = 1821]
2008-07-05 23:56:24 -08:00

660 lines
18 KiB
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#include "solvespace.h"
SBsp2 *SBsp2::Alloc(void) { return (SBsp2 *)AllocTemporary(sizeof(SBsp2)); }
SBsp3 *SBsp3::Alloc(void) { return (SBsp3 *)AllocTemporary(sizeof(SBsp3)); }
static int ByArea(const void *av, const void *bv) {
STriangle *a = (STriangle *)av;
STriangle *b = (STriangle *)bv;
double fa = a->Normal().Magnitude();
double fb = b->Normal().Magnitude();
if(fa > fb) {
return -1;
} else if(fa < fb) {
return 1;
} else {
return 0;
}
}
SBsp3 *SBsp3::FromMesh(SMesh *m) {
SBsp3 *bsp3 = NULL;
int i;
SMesh mc; ZERO(&mc);
for(i = 0; i < m->l.n; i++) {
mc.AddTriangle(&(m->l.elem[i]));
}
// The larger-area triangles have more trustworthy normals. By inserting
// those first, we hope to improve the numerical accuracy of our
// split planes.
qsort(mc.l.elem, mc.l.n, sizeof(mc.l.elem[0]), ByArea);
for(i = 0; i < mc.l.n; i++) {
bsp3 = bsp3->Insert(&(mc.l.elem[i]), NULL);
}
mc.Clear();
return bsp3;
}
Vector SBsp3::IntersectionWith(Vector a, Vector b) {
double da = a.Dot(n) - d;
double db = b.Dot(n) - d;
if(da*db > 0) oops();
double dab = (db - da);
return (a.ScaledBy(db/dab)).Plus(b.ScaledBy(-da/dab));
}
void SBsp3::InsertInPlane(bool pos2, STriangle *tr, SMesh *m) {
Vector tc = ((tr->a).Plus(tr->b).Plus(tr->c)).ScaledBy(1.0/3);
bool onFace = false;
bool sameNormal;
double maxNormalMag = -1;
Vector lln, trn = tr->Normal();
SBsp3 *ll = this;
while(ll) {
if((ll->tri).ContainsPoint(tc)) {
onFace = true;
// If the mesh contains almost-zero-area triangles, and we're
// just on the edge of one of those, then don't trust its normal.
lln = (ll->tri).Normal();
if(lln.Magnitude() > maxNormalMag) {
sameNormal = trn.Dot(lln) > 0;
maxNormalMag = lln.Magnitude();
}
}
ll = ll->more;
}
if(m->flipNormal && ((!pos2 && !onFace) ||
(onFace && !sameNormal && m->keepCoplanar)))
{
m->AddTriangle(tr->meta, tr->c, tr->b, tr->a);
} else if(!(m->flipNormal) && ((pos2 && !onFace) ||
(onFace && sameNormal && m->keepCoplanar)))
{
m->AddTriangle(tr->meta, tr->a, tr->b, tr->c);
} else {
m->atLeastOneDiscarded = true;
}
}
void SBsp3::InsertHow(int how, STriangle *tr, SMesh *instead) {
switch(how) {
case POS:
if(instead && !pos) goto alt;
pos = pos->Insert(tr, instead);
break;
case NEG:
if(instead && !neg) goto alt;
neg = neg->Insert(tr, instead);
break;
case COPLANAR: {
if(instead) goto alt;
SBsp3 *m = Alloc();
m->n = n;
m->d = d;
m->tri = *tr;
m->more = more;
more = m;
break;
}
default: oops();
}
return;
alt:
if(how == POS && !(instead->flipNormal)) {
instead->AddTriangle(tr->meta, tr->a, tr->b, tr->c);
} else if(how == NEG && instead->flipNormal) {
instead->AddTriangle(tr->meta, tr->c, tr->b, tr->a);
} else if(how == COPLANAR) {
if(edges) {
edges->InsertTriangle(tr, instead, this);
} else {
// I suppose this actually is allowed to happen, if the coplanar
// face is the leaf, and all of its neighbors are earlier in tree?
InsertInPlane(false, tr, instead);
}
} else {
instead->atLeastOneDiscarded = true;
}
}
void SBsp3::InsertConvexHow(int how, STriMeta meta, Vector *vertex, int n,
SMesh *instead)
{
switch(how) {
case POS:
if(pos) {
pos = pos->InsertConvex(meta, vertex, n, instead);
return;
}
break;
case NEG:
if(neg) {
neg = neg->InsertConvex(meta, vertex, n, instead);
return;
}
break;
default: oops();
}
int i;
for(i = 0; i < n - 2; i++) {
STriangle tr = STriangle::From(meta,
vertex[0], vertex[i+1], vertex[i+2]);
InsertHow(how, &tr, instead);
}
}
SBsp3 *SBsp3::InsertConvex(STriMeta meta, Vector *vertex, int cnt,
SMesh *instead)
{
Vector e01 = (vertex[1]).Minus(vertex[0]);
Vector e12 = (vertex[2]).Minus(vertex[1]);
Vector out = e01.Cross(e12);
#define MAX_VERTICES 50
if(cnt+1 >= MAX_VERTICES) goto triangulate;
int i;
Vector on[2];
bool isPos[MAX_VERTICES];
bool isNeg[MAX_VERTICES];
bool isOn[MAX_VERTICES];
int posc = 0, negc = 0, onc = 0;
for(i = 0; i < cnt; i++) {
double dt = n.Dot(vertex[i]);
isPos[i] = isNeg[i] = isOn[i] = false;
if(fabs(dt - d) < LENGTH_EPS) {
isOn[i] = true;
if(onc < 2) {
on[onc] = vertex[i];
}
onc++;
} else if(dt > d) {
isPos[i] = true;
posc++;
} else {
isNeg[i] = true;
negc++;
}
}
if(onc != 2 && onc != 1 && onc != 0) goto triangulate;
if(onc == 2) {
if(!instead) {
SEdge se = SEdge::From(on[0], on[1]);
edges = edges->InsertEdge(&se, n, out);
}
}
if(posc == 0) {
InsertConvexHow(NEG, meta, vertex, cnt, instead);
return this;
}
if(negc == 0) {
InsertConvexHow(POS, meta, vertex, cnt, instead);
return this;
}
Vector vpos[MAX_VERTICES];
Vector vneg[MAX_VERTICES];
int npos = 0, nneg = 0;
Vector inter[2];
int inters = 0;
for(i = 0; i < cnt; i++) {
int ip = WRAP((i + 1), cnt);
if(isPos[i]) {
vpos[npos++] = vertex[i];
}
if(isNeg[i]) {
vneg[nneg++] = vertex[i];
}
if(isOn[i]) {
vneg[nneg++] = vertex[i];
vpos[npos++] = vertex[i];
}
if((isPos[i] && isNeg[ip]) || (isNeg[i] && isPos[ip])) {
Vector vi = IntersectionWith(vertex[i], vertex[ip]);
vpos[npos++] = vi;
vneg[nneg++] = vi;
if(inters >= 2) oops();
inter[inters++] = vi;
}
}
if(npos > cnt + 1 || nneg > cnt + 1) oops();
if(!instead) {
if(inters == 2) {
SEdge se = SEdge::From(inter[0], inter[1]);
edges = edges->InsertEdge(&se, n, out);
} else if(inters == 1 && onc == 1) {
SEdge se = SEdge::From(inter[0], on[0]);
edges = edges->InsertEdge(&se, n, out);
} else if(inters == 0 && onc == 2) {
// We already handled this on-plane existing edge
} else oops();
}
if(nneg < 3 || npos < 3) oops();
InsertConvexHow(NEG, meta, vneg, nneg, instead);
InsertConvexHow(POS, meta, vpos, npos, instead);
return this;
triangulate:
// We don't handle the special case for this; do it as triangles
SBsp3 *r = this;
for(i = 0; i < cnt - 2; i++) {
STriangle tr = STriangle::From(meta,
vertex[0], vertex[i+1], vertex[i+2]);
r = r->Insert(&tr, instead);
}
return r;
}
SBsp3 *SBsp3::Insert(STriangle *tr, SMesh *instead) {
if(!this) {
if(instead) {
if(instead->flipNormal) {
instead->atLeastOneDiscarded = true;
} else {
instead->AddTriangle(tr->meta, tr->a, tr->b, tr->c);
}
return NULL;
}
// Brand new node; so allocate for it, and fill us in.
SBsp3 *r = Alloc();
r->n = (tr->Normal()).WithMagnitude(1);
r->d = (tr->a).Dot(r->n);
r->tri = *tr;
return r;
}
double dt[3] = { (tr->a).Dot(n), (tr->b).Dot(n), (tr->c).Dot(n) };
int inc = 0, posc = 0, negc = 0;
bool isPos[3], isNeg[3], isOn[3];
ZERO(&isPos); ZERO(&isNeg); ZERO(&isOn);
// Count vertices in the plane
for(int i = 0; i < 3; i++) {
if(fabs(dt[i] - d) < LENGTH_EPS) {
inc++;
isOn[i] = true;
} else if(dt[i] > d) {
posc++;
isPos[i] = true;
} else {
negc++;
isNeg[i] = true;
}
}
// All vertices in-plane
if(inc == 3) {
InsertHow(COPLANAR, tr, instead);
return this;
}
// No split required
if(posc == 0 || negc == 0) {
if(inc == 2) {
Vector a, b;
if (!isOn[0]) { a = tr->b; b = tr->c; }
else if(!isOn[1]) { a = tr->c; b = tr->a; }
else if(!isOn[2]) { a = tr->a; b = tr->b; }
else oops();
if(!instead) {
SEdge se = SEdge::From(a, b);
edges = edges->InsertEdge(&se, n, tr->Normal());
}
}
if(posc > 0) {
InsertHow(POS, tr, instead);
} else {
InsertHow(NEG, tr, instead);
}
return this;
}
// The polygon must be split into two pieces, one above, one below.
Vector a, b, c;
if(posc == 1 && negc == 1 && inc == 1) {
bool bpos;
// Standardize so that a is on the plane
if (isOn[0]) { a = tr->a; b = tr->b; c = tr->c; bpos = isPos[1];
} else if(isOn[1]) { a = tr->b; b = tr->c; c = tr->a; bpos = isPos[2];
} else if(isOn[2]) { a = tr->c; b = tr->a; c = tr->b; bpos = isPos[0];
} else oops();
Vector bPc = IntersectionWith(b, c);
STriangle btri = STriangle::From(tr->meta, a, b, bPc);
STriangle ctri = STriangle::From(tr->meta, c, a, bPc);
if(bpos) {
InsertHow(POS, &btri, instead);
InsertHow(NEG, &ctri, instead);
} else {
InsertHow(POS, &ctri, instead);
InsertHow(NEG, &btri, instead);
}
if(!instead) {
SEdge se = SEdge::From(a, bPc);
edges = edges->InsertEdge(&se, n, tr->Normal());
}
return this;
}
if(posc == 2 && negc == 1) {
// Standardize so that a is on one side, and b and c are on the other.
if (isNeg[0]) { a = tr->a; b = tr->b; c = tr->c;
} else if(isNeg[1]) { a = tr->b; b = tr->c; c = tr->a;
} else if(isNeg[2]) { a = tr->c; b = tr->a; c = tr->b;
} else oops();
} else if(posc == 1 && negc == 2) {
if (isPos[0]) { a = tr->a; b = tr->b; c = tr->c;
} else if(isPos[1]) { a = tr->b; b = tr->c; c = tr->a;
} else if(isPos[2]) { a = tr->c; b = tr->a; c = tr->b;
} else oops();
} else oops();
Vector aPb = IntersectionWith(a, b);
Vector cPa = IntersectionWith(c, a);
STriangle alone = STriangle::From(tr->meta, a, aPb, cPa);
Vector quad[4] = { aPb, b, c, cPa };
if(posc == 2 && negc == 1) {
InsertConvexHow(POS, tr->meta, quad, 4, instead);
InsertHow(NEG, &alone, instead);
} else {
InsertConvexHow(NEG, tr->meta, quad, 4, instead);
InsertHow(POS, &alone, instead);
}
if(!instead) {
SEdge se = SEdge::From(aPb, cPa);
edges = edges->InsertEdge(&se, n, alone.Normal());
}
return this;
}
void SBsp3::DebugDraw(void) {
if(!this) return;
pos->DebugDraw();
Vector norm = tri.Normal();
glNormal3d(norm.x, norm.y, norm.z);
glEnable(GL_DEPTH_TEST);
glEnable(GL_LIGHTING);
glBegin(GL_TRIANGLES);
glxVertex3v(tri.a);
glxVertex3v(tri.b);
glxVertex3v(tri.c);
glEnd();
glDisable(GL_LIGHTING);
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
glxDepthRangeOffset(2);
glBegin(GL_TRIANGLES);
glxVertex3v(tri.a);
glxVertex3v(tri.b);
glxVertex3v(tri.c);
glEnd();
glDisable(GL_LIGHTING);
glPolygonMode(GL_FRONT_AND_BACK, GL_POINT);
glPointSize(10);
glxDepthRangeOffset(2);
glBegin(GL_TRIANGLES);
glxVertex3v(tri.a);
glxVertex3v(tri.b);
glxVertex3v(tri.c);
glEnd();
glxDepthRangeOffset(0);
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
more->DebugDraw();
neg->DebugDraw();
edges->DebugDraw(n, d);
}
/////////////////////////////////
Vector SBsp2::IntersectionWith(Vector a, Vector b) {
double da = a.Dot(no) - d;
double db = b.Dot(no) - d;
if(da*db > 0) oops();
double dab = (db - da);
return (a.ScaledBy(db/dab)).Plus(b.ScaledBy(-da/dab));
}
SBsp2 *SBsp2::InsertEdge(SEdge *nedge, Vector nnp, Vector out) {
if(!this) {
// Brand new node; so allocate for it, and fill us in.
SBsp2 *r = Alloc();
r->np = nnp;
r->no = ((r->np).Cross((nedge->b).Minus(nedge->a))).WithMagnitude(1);
if(out.Dot(r->no) < 0) {
r->no = (r->no).ScaledBy(-1);
}
r->d = (nedge->a).Dot(r->no);
r->edge = *nedge;
return r;
}
double dt[2] = { (nedge->a).Dot(no), (nedge->b).Dot(no) };
bool isPos[2], isNeg[2], isOn[2];
ZERO(&isPos); ZERO(&isNeg); ZERO(&isOn);
for(int i = 0; i < 2; i++) {
if(fabs(dt[i] - d) < LENGTH_EPS) {
isOn[i] = true;
} else if(dt[i] > d) {
isPos[i] = true;
} else {
isNeg[i] = true;
}
}
if((isPos[0] && isPos[1])||(isPos[0] && isOn[1])||(isOn[0] && isPos[1])) {
pos = pos->InsertEdge(nedge, nnp, out);
return this;
}
if((isNeg[0] && isNeg[1])||(isNeg[0] && isOn[1])||(isOn[0] && isNeg[1])) {
neg = neg->InsertEdge(nedge, nnp, out);
return this;
}
if(isOn[0] && isOn[1]) {
SBsp2 *m = Alloc();
m->np = nnp;
m->no = ((m->np).Cross((nedge->b).Minus(nedge->a))).WithMagnitude(1);
if(out.Dot(m->no) < 0) {
m->no = (m->no).ScaledBy(-1);
}
m->d = (nedge->a).Dot(m->no);
m->edge = *nedge;
m->more = more;
more = m;
return this;
}
if((isPos[0] && isNeg[1]) || (isNeg[0] && isPos[1])) {
Vector aPb = IntersectionWith(nedge->a, nedge->b);
SEdge ea = SEdge::From(nedge->a, aPb);
SEdge eb = SEdge::From(aPb, nedge->b);
if(isPos[0]) {
pos = pos->InsertEdge(&ea, nnp, out);
neg = neg->InsertEdge(&eb, nnp, out);
} else {
neg = neg->InsertEdge(&ea, nnp, out);
pos = pos->InsertEdge(&eb, nnp, out);
}
return this;
}
oops();
}
void SBsp2::InsertTriangleHow(int how, STriangle *tr, SMesh *m, SBsp3 *bsp3) {
switch(how) {
case POS:
if(pos) {
pos->InsertTriangle(tr, m, bsp3);
} else {
bsp3->InsertInPlane(true, tr, m);
}
break;
case NEG:
if(neg) {
neg->InsertTriangle(tr, m, bsp3);
} else {
bsp3->InsertInPlane(false, tr, m);
}
break;
default: oops();
}
}
void SBsp2::InsertTriangle(STriangle *tr, SMesh *m, SBsp3 *bsp3) {
double dt[3] = { (tr->a).Dot(no), (tr->b).Dot(no), (tr->c).Dot(no) };
bool isPos[3], isNeg[3], isOn[3];
int inc = 0, posc = 0, negc = 0;
ZERO(&isPos); ZERO(&isNeg); ZERO(&isOn);
for(int i = 0; i < 3; i++) {
if(fabs(dt[i] - d) < LENGTH_EPS) {
isOn[i] = true;
inc++;
} else if(dt[i] > d) {
isPos[i] = true;
posc++;
} else {
isNeg[i] = true;
negc++;
}
}
if(inc == 3) {
// All vertices on-line; so it's a degenerate triangle, to ignore.
return;
}
// No split required
if(posc == 0 || negc == 0) {
if(posc > 0) {
InsertTriangleHow(POS, tr, m, bsp3);
} else {
InsertTriangleHow(NEG, tr, m, bsp3);
}
return;
}
// The polygon must be split into two pieces, one above, one below.
Vector a, b, c;
if(posc == 1 && negc == 1 && inc == 1) {
bool bpos;
// Standardize so that a is on the plane
if (isOn[0]) { a = tr->a; b = tr->b; c = tr->c; bpos = isPos[1];
} else if(isOn[1]) { a = tr->b; b = tr->c; c = tr->a; bpos = isPos[2];
} else if(isOn[2]) { a = tr->c; b = tr->a; c = tr->b; bpos = isPos[0];
} else oops();
Vector bPc = IntersectionWith(b, c);
STriangle btri = STriangle::From(tr->meta, a, b, bPc);
STriangle ctri = STriangle::From(tr->meta, c, a, bPc);
if(bpos) {
InsertTriangleHow(POS, &btri, m, bsp3);
InsertTriangleHow(NEG, &ctri, m, bsp3);
} else {
InsertTriangleHow(POS, &ctri, m, bsp3);
InsertTriangleHow(NEG, &btri, m, bsp3);
}
return;
}
if(posc == 2 && negc == 1) {
// Standardize so that a is on one side, and b and c are on the other.
if (isNeg[0]) { a = tr->a; b = tr->b; c = tr->c;
} else if(isNeg[1]) { a = tr->b; b = tr->c; c = tr->a;
} else if(isNeg[2]) { a = tr->c; b = tr->a; c = tr->b;
} else oops();
} else if(posc == 1 && negc == 2) {
if (isPos[0]) { a = tr->a; b = tr->b; c = tr->c;
} else if(isPos[1]) { a = tr->b; b = tr->c; c = tr->a;
} else if(isPos[2]) { a = tr->c; b = tr->a; c = tr->b;
} else oops();
} else oops();
Vector aPb = IntersectionWith(a, b);
Vector cPa = IntersectionWith(c, a);
STriangle alone = STriangle::From(tr->meta, a, aPb, cPa);
STriangle quad1 = STriangle::From(tr->meta, aPb, b, c );
STriangle quad2 = STriangle::From(tr->meta, aPb, c, cPa);
if(posc == 2 && negc == 1) {
InsertTriangleHow(POS, &quad1, m, bsp3);
InsertTriangleHow(POS, &quad2, m, bsp3);
InsertTriangleHow(NEG, &alone, m, bsp3);
} else {
InsertTriangleHow(NEG, &quad1, m, bsp3);
InsertTriangleHow(NEG, &quad2, m, bsp3);
InsertTriangleHow(POS, &alone, m, bsp3);
}
return;
}
void SBsp2::DebugDraw(Vector n, double d) {
if(!this) return;
if(fabs((edge.a).Dot(n) - d) > LENGTH_EPS) oops();
if(fabs((edge.b).Dot(n) - d) > LENGTH_EPS) oops();
glLineWidth(10);
glBegin(GL_LINES);
glxVertex3v(edge.a);
glxVertex3v(edge.b);
glEnd();
pos->DebugDraw(n, d);
neg->DebugDraw(n, d);
more->DebugDraw(n, d);
glLineWidth(1);
}
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