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solvespace/srf/surface.cpp

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C++
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//-----------------------------------------------------------------------------
// Anything involving surfaces and sets of surfaces (i.e., shells); except
// for the real math, which is in ratpoly.cpp.
//-----------------------------------------------------------------------------
#include "../solvespace.h"
SSurface SSurface::FromExtrusionOf(SBezier *sb, Vector t0, Vector t1) {
SSurface ret;
ZERO(&ret);
ret.degm = sb->deg;
ret.degn = 1;
int i;
for(i = 0; i <= ret.degm; i++) {
ret.ctrl[i][0] = (sb->ctrl[i]).Plus(t0);
ret.weight[i][0] = sb->weight[i];
ret.ctrl[i][1] = (sb->ctrl[i]).Plus(t1);
ret.weight[i][1] = sb->weight[i];
}
return ret;
}
bool SSurface::IsExtrusion(SBezier *of, Vector *alongp) {
int i;
if(degn != 1) return false;
Vector along = (ctrl[0][1]).Minus(ctrl[0][0]);
for(i = 0; i <= degm; i++) {
if((fabs(weight[i][1] - weight[i][0]) < LENGTH_EPS) &&
((ctrl[i][1]).Minus(ctrl[i][0])).Equals(along))
{
continue;
}
return false;
}
// yes, we are a surface of extrusion; copy the original curve and return
if(of) {
for(i = 0; i <= degm; i++) {
of->weight[i] = weight[i][0];
of->ctrl[i] = ctrl[i][0];
}
of->deg = degm;
*alongp = along;
}
return true;
}
bool SSurface::IsCylinder(Vector *center, Vector *axis, double *r,
Vector *start, Vector *finish)
{
SBezier sb;
if(!IsExtrusion(&sb, axis)) return false;
if(sb.deg != 2) return false;
Vector t0 = (sb.ctrl[0]).Minus(sb.ctrl[1]),
t2 = (sb.ctrl[2]).Minus(sb.ctrl[1]),
r0 = axis->Cross(t0),
r2 = axis->Cross(t2);
*center = Vector::AtIntersectionOfLines(sb.ctrl[0], (sb.ctrl[0]).Plus(r0),
sb.ctrl[2], (sb.ctrl[2]).Plus(r2),
NULL, NULL, NULL);
double rd0 = center->Minus(sb.ctrl[0]).Magnitude(),
rd2 = center->Minus(sb.ctrl[2]).Magnitude();
if(fabs(rd0 - rd2) > LENGTH_EPS) {
return false;
}
*r = rd0;
Vector u = r0.WithMagnitude(1),
v = (axis->Cross(u)).WithMagnitude(1);
Point2d c2 = center->Project2d(u, v),
pa2 = (sb.ctrl[0]).Project2d(u, v).Minus(c2),
pb2 = (sb.ctrl[2]).Project2d(u, v).Minus(c2);
double thetaa = atan2(pa2.y, pa2.x), // in fact always zero due to csys
thetab = atan2(pb2.y, pb2.x),
dtheta = WRAP_NOT_0(thetab - thetaa, 2*PI);
if(dtheta > PI) {
// Not possible with a second order Bezier arc; so we must have
// the points backwards.
dtheta = 2*PI - dtheta;
}
if(fabs(sb.weight[1] - cos(dtheta/2)) > LENGTH_EPS) {
return false;
}
*start = sb.ctrl[0];
*finish = sb.ctrl[2];
return true;
}
SSurface SSurface::FromPlane(Vector pt, Vector u, Vector v) {
SSurface ret;
ZERO(&ret);
ret.degm = 1;
ret.degn = 1;
ret.weight[0][0] = ret.weight[0][1] = 1;
ret.weight[1][0] = ret.weight[1][1] = 1;
ret.ctrl[0][0] = pt;
ret.ctrl[0][1] = pt.Plus(u);
ret.ctrl[1][0] = pt.Plus(v);
ret.ctrl[1][1] = pt.Plus(v).Plus(u);
return ret;
}
SSurface SSurface::FromTransformationOf(SSurface *a, Vector t, Quaternion q,
bool includingTrims)
{
SSurface ret;
ZERO(&ret);
ret.h = a->h;
ret.color = a->color;
ret.face = a->face;
ret.degm = a->degm;
ret.degn = a->degn;
int i, j;
for(i = 0; i <= 3; i++) {
for(j = 0; j <= 3; j++) {
ret.ctrl[i][j] = (q.Rotate(a->ctrl[i][j])).Plus(t);
ret.weight[i][j] = a->weight[i][j];
}
}
if(includingTrims) {
STrimBy *stb;
for(stb = a->trim.First(); stb; stb = a->trim.NextAfter(stb)) {
STrimBy n = *stb;
n.start = (q.Rotate(n.start)) .Plus(t);
n.finish = (q.Rotate(n.finish)).Plus(t);
ret.trim.Add(&n);
}
}
return ret;
}
void SSurface::GetAxisAlignedBounding(Vector *ptMax, Vector *ptMin) {
*ptMax = Vector::From(VERY_NEGATIVE, VERY_NEGATIVE, VERY_NEGATIVE);
*ptMin = Vector::From(VERY_POSITIVE, VERY_POSITIVE, VERY_POSITIVE);
int i, j;
for(i = 0; i <= degm; i++) {
for(j = 0; j <= degn; j++) {
(ctrl[i][j]).MakeMaxMin(ptMax, ptMin);
}
}
}
bool SSurface::LineEntirelyOutsideBbox(Vector a, Vector b, bool segment) {
Vector amax, amin;
GetAxisAlignedBounding(&amax, &amin);
if(!Vector::BoundingBoxIntersectsLine(amax, amin, a, b, segment)) {
// The line segment could fail to intersect the bbox, but lie entirely
// within it and intersect the surface.
if(a.OutsideAndNotOn(amax, amin) && b.OutsideAndNotOn(amax, amin)) {
return true;
}
}
return false;
}
void SSurface::MakeEdgesInto(SShell *shell, SEdgeList *sel, bool asUv,
SShell *useCurvesFrom)
{
STrimBy *stb;
for(stb = trim.First(); stb; stb = trim.NextAfter(stb)) {
SCurve *sc = shell->curve.FindById(stb->curve);
// We have the option to use the curves from another shell; this
// is relevant when generating the coincident edges while doing the
// Booleans, since the curves from the output shell will be split
// against any intersecting surfaces (and the originals aren't).
if(useCurvesFrom) {
sc = useCurvesFrom->curve.FindById(sc->newH);
}
Vector prev, prevuv, ptuv;
bool inCurve = false, empty = true;
double u = 0, v = 0;
int i, first, last, increment;
if(stb->backwards) {
first = sc->pts.n - 1;
last = 0;
increment = -1;
} else {
first = 0;
last = sc->pts.n - 1;
increment = 1;
}
for(i = first; i != (last + increment); i += increment) {
Vector *pt = &(sc->pts.elem[i]);
if(asUv) {
ClosestPointTo(*pt, &u, &v);
ptuv = Vector::From(u, v, 0);
if(inCurve) {
sel->AddEdge(prevuv, ptuv, sc->h.v, stb->backwards);
empty = false;
}
prevuv = ptuv;
} else {
if(inCurve) {
sel->AddEdge(prev, *pt, sc->h.v, stb->backwards);
empty = false;
}
prev = *pt;
}
if(pt->Equals(stb->start)) inCurve = true;
if(pt->Equals(stb->finish)) inCurve = false;
}
if(inCurve) dbp("trim was unterminated");
if(empty) dbp("trim was empty");
}
}
void SSurface::TriangulateInto(SShell *shell, SMesh *sm) {
SEdgeList el;
ZERO(&el);
MakeEdgesInto(shell, &el, true);
SPolygon poly;
ZERO(&poly);
if(el.AssemblePolygon(&poly, NULL, true)) {
int i, start = sm->l.n;
// Curved surfaces are triangulated in such a way as to minimize
// deviation between edges and surface; but doesn't matter for planes.
poly.UvTriangulateInto(sm, (degm == 1 && degn == 1) ? NULL : this);
STriMeta meta = { face, color };
for(i = start; i < sm->l.n; i++) {
STriangle *st = &(sm->l.elem[i]);
st->meta = meta;
st->an = NormalAt(st->a.x, st->a.y);
st->bn = NormalAt(st->b.x, st->b.y);
st->cn = NormalAt(st->c.x, st->c.y);
st->a = PointAt(st->a.x, st->a.y);
st->b = PointAt(st->b.x, st->b.y);
st->c = PointAt(st->c.x, st->c.y);
// Works out that my chosen contour direction is inconsistent with
// the triangle direction, sigh.
st->FlipNormal();
}
} else {
dbp("failed to assemble polygon to trim nurbs surface in uv space");
}
el.Clear();
poly.Clear();
}
//-----------------------------------------------------------------------------
// Reverse the parametrisation of one of our dimensions, which flips the
// normal. We therefore must reverse all our trim curves too. The uv
// coordinates change, but trim curves are stored as xyz so nothing happens
//-----------------------------------------------------------------------------
void SSurface::Reverse(void) {
int i, j;
for(i = 0; i < (degm+1)/2; i++) {
for(j = 0; j <= degn; j++) {
SWAP(Vector, ctrl[i][j], ctrl[degm-i][j]);
SWAP(double, weight[i][j], weight[degm-i][j]);
}
}
STrimBy *stb;
for(stb = trim.First(); stb; stb = trim.NextAfter(stb)) {
stb->backwards = !stb->backwards;
SWAP(Vector, stb->start, stb->finish);
}
}
void SSurface::Clear(void) {
trim.Clear();
}
void SShell::MakeFromExtrusionOf(SBezierLoopSet *sbls, Vector t0, Vector t1,
int color)
{
ZERO(this);
// Make the extrusion direction consistent with respect to the normal
// of the sketch we're extruding.
if((t0.Minus(t1)).Dot(sbls->normal) < 0) {
SWAP(Vector, t0, t1);
}
// Define a coordinate system to contain the original sketch, and get
// a bounding box in that csys
Vector n = sbls->normal.ScaledBy(-1);
Vector u = n.Normal(0), v = n.Normal(1);
Vector orig = sbls->point;
double umax = 1e-10, umin = 1e10;
sbls->GetBoundingProjd(u, orig, &umin, &umax);
double vmax = 1e-10, vmin = 1e10;
sbls->GetBoundingProjd(v, orig, &vmin, &vmax);
// and now fix things up so that all u and v lie between 0 and 1
orig = orig.Plus(u.ScaledBy(umin));
orig = orig.Plus(v.ScaledBy(vmin));
u = u.ScaledBy(umax - umin);
v = v.ScaledBy(vmax - vmin);
// So we can now generate the top and bottom surfaces of the extrusion,
// planes within a translated (and maybe mirrored) version of that csys.
SSurface s0, s1;
s0 = SSurface::FromPlane(orig.Plus(t0), u, v);
s0.color = color;
s1 = SSurface::FromPlane(orig.Plus(t1).Plus(u), u.ScaledBy(-1), v);
s1.color = color;
hSSurface hs0 = surface.AddAndAssignId(&s0),
hs1 = surface.AddAndAssignId(&s1);
// Now go through the input curves. For each one, generate its surface
// of extrusion, its two translated trim curves, and one trim line. We
// go through by loops so that we can assign the lines correctly.
SBezierLoop *sbl;
for(sbl = sbls->l.First(); sbl; sbl = sbls->l.NextAfter(sbl)) {
SBezier *sb;
typedef struct {
hSCurve hc;
hSSurface hs;
} TrimLine;
List<TrimLine> trimLines;
ZERO(&trimLines);
for(sb = sbl->l.First(); sb; sb = sbl->l.NextAfter(sb)) {
// Generate the surface of extrusion of this curve, and add
// it to the list
SSurface ss = SSurface::FromExtrusionOf(sb, t0, t1);
ss.color = color;
hSSurface hsext = surface.AddAndAssignId(&ss);
// Translate the curve by t0 and t1 to produce two trim curves
SCurve sc;
ZERO(&sc);
sc.isExact = true;
sc.exact = sb->TransformedBy(t0, Quaternion::IDENTITY);
(sc.exact).MakePwlInto(&(sc.pts));
sc.surfA = hs0;
sc.surfB = hsext;
hSCurve hc0 = curve.AddAndAssignId(&sc);
ZERO(&sc);
sc.isExact = true;
sc.exact = sb->TransformedBy(t1, Quaternion::IDENTITY);
(sc.exact).MakePwlInto(&(sc.pts));
sc.surfA = hs1;
sc.surfB = hsext;
hSCurve hc1 = curve.AddAndAssignId(&sc);
STrimBy stb0, stb1;
// The translated curves trim the flat top and bottom surfaces.
stb0 = STrimBy::EntireCurve(this, hc0, false);
stb1 = STrimBy::EntireCurve(this, hc1, true);
(surface.FindById(hs0))->trim.Add(&stb0);
(surface.FindById(hs1))->trim.Add(&stb1);
// The translated curves also trim the surface of extrusion.
stb0 = STrimBy::EntireCurve(this, hc0, true);
stb1 = STrimBy::EntireCurve(this, hc1, false);
(surface.FindById(hsext))->trim.Add(&stb0);
(surface.FindById(hsext))->trim.Add(&stb1);
// And form the trim line
Vector pt = sb->Finish();
ZERO(&sc);
sc.isExact = true;
sc.exact = SBezier::From(pt.Plus(t0), pt.Plus(t1));
(sc.exact).MakePwlInto(&(sc.pts));
hSCurve hl = curve.AddAndAssignId(&sc);
// save this for later
TrimLine tl;
tl.hc = hl;
tl.hs = hsext;
trimLines.Add(&tl);
}
int i;
for(i = 0; i < trimLines.n; i++) {
TrimLine *tl = &(trimLines.elem[i]);
SSurface *ss = surface.FindById(tl->hs);
TrimLine *tlp = &(trimLines.elem[WRAP(i-1, trimLines.n)]);
STrimBy stb;
stb = STrimBy::EntireCurve(this, tl->hc, true);
ss->trim.Add(&stb);
stb = STrimBy::EntireCurve(this, tlp->hc, false);
ss->trim.Add(&stb);
(curve.FindById(tl->hc))->surfA = ss->h;
(curve.FindById(tlp->hc))->surfB = ss->h;
}
trimLines.Clear();
}
}
void SShell::MakeFromCopyOf(SShell *a) {
MakeFromTransformationOf(a, Vector::From(0, 0, 0), Quaternion::IDENTITY);
}
void SShell::MakeFromTransformationOf(SShell *a, Vector t, Quaternion q) {
SSurface *s;
for(s = a->surface.First(); s; s = a->surface.NextAfter(s)) {
SSurface n;
n = SSurface::FromTransformationOf(s, t, q, true);
surface.Add(&n); // keeping the old ID
}
SCurve *c;
for(c = a->curve.First(); c; c = a->curve.NextAfter(c)) {
SCurve n;
n = SCurve::FromTransformationOf(c, t, q);
curve.Add(&n); // keeping the old ID
}
}
void SShell::MakeEdgesInto(SEdgeList *sel) {
SSurface *s;
for(s = surface.First(); s; s = surface.NextAfter(s)) {
s->MakeEdgesInto(this, sel, false);
}
}
void SShell::TriangulateInto(SMesh *sm) {
SSurface *s;
for(s = surface.First(); s; s = surface.NextAfter(s)) {
s->TriangulateInto(this, sm);
}
}
void SShell::Clear(void) {
SSurface *s;
for(s = surface.First(); s; s = surface.NextAfter(s)) {
s->Clear();
}
surface.Clear();
SCurve *c;
for(c = curve.First(); c; c = curve.NextAfter(c)) {
c->Clear();
}
curve.Clear();
}
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