Back to opengl's tesselator for triangulation. I'll spend more time

writing mine later.

[git-p4: depot-paths = "//depot/solvespace/": change = 1810]

dsc.h

@@ -45,8 +45,6 @@ public:
     static Vector From(hParam x, hParam y, hParam z);
     static Vector AtIntersectionOfPlanes(Vector n1, double d1,
                                          Vector n2, double d2);
-    static bool LinesIntersect(Vector a0, Vector da, Vector b0, Vector db,
-                               double *ta, double *tb);
 
     bool Equals(Vector v);
     Vector Plus(Vector b);

polygon.cpp

@@ -314,246 +314,62 @@ bool SPolygon::AllPointsInPlane(Vector *notCoplanarAt) {
     return true;
 }
 
-bool SPolygon::IntersectsPolygon(Vector ga, Vector gb) {
+static int TriMode, TriVertexCount;
-    int i, j;
+static Vector Tri1, TriNMinus1, TriNMinus2;
-    for(i = 0; i < l.n; i++) {
+static Vector TriNormal;
-        SContour *sc = &(l.elem[i]);
+static SMesh *TriMesh;
-        for(j = 0; j < sc->l.n; j++) {
+static STriMeta TriMeta;
-            Vector pa = sc->l.elem[j].p,
+static void GLX_CALLBACK TriBegin(int mode) 
-                   pb = sc->l.elem[WRAP(j+1, (sc->l.n - 1))].p;
-            // So do the lines from (ga to gb) and (pa to pb) intersect?
-            Vector dp = pb.Minus(pa),    dg = gb.Minus(ga);
-            double tp, tg;
-            if(!Vector::LinesIntersect(pa, dp, ga, dg, &tp, &tg)) {
-                continue;
-            }
-
-            // So check if the line segments intersect
-            double lp = dp.Magnitude(),  lg = dg.Magnitude();
-            tp *= lp;
-            tg *= lg;
-
-            if(tg > LENGTH_EPS && tg < (lg - LENGTH_EPS) &&
-               tp > LENGTH_EPS && tp < (lp - LENGTH_EPS))
-            {
-                return true;
-            }
-        }
-    }
-    return false;
-}
-
-bool SPolygon::VisibleVertices(SContour *outer, SContour *inner,
-                               SEdgeList *extras, int *vo, int *vi)
 {
-    int i, j, k;
+    TriMode = mode;
-
+    TriVertexCount = 0;
-    double lmin = 1e12;
-    for(i = 0; i < outer->l.n; i++) {
-        Vector op = outer->l.elem[i].p;
-
-        for(j = 0; j < inner->l.n; j++) {
-            Vector ip = inner->l.elem[j].p;
-
-            if(IntersectsPolygon(op, ip)) goto dontuse;
-
-            for(k = 0; k < extras->l.n; k++) {
-                SEdge *se = &(extras->l.elem[k]);
-
-                if(ip.Equals(se->a) || ip.Equals(se->b) ||
-                   op.Equals(se->a) || op.Equals(se->b))
-                {
-                    goto dontuse;
-                }
-                
-                Vector dt = ip.Minus(op), de = (se->b).Minus(se->a);
-                double te, tt;
-                if(!Vector::LinesIntersect(op, dt, se->a, de, &tt, &te))
-                    continue;
-
-                double le = de.Magnitude(), lt = dt.Magnitude();
-                tt *= lt;
-                te *= le;
-                if(tt > LENGTH_EPS && tt < (lt - LENGTH_EPS) &&
-                   te > LENGTH_EPS && te < (le - LENGTH_EPS))
-                {
-                    goto dontuse;
-                }
-            }
-
-            if((op.Minus(ip)).Magnitude() < lmin) {
-                lmin = (op.Minus(ip)).Magnitude();
-                *vo = i;
-                *vi = j;
-            }
-dontuse:;
-        }
-    }
-    if(lmin < 1e12) {
-        return true;
-    } else {
-        return false;
-    }
 }
-
+static void GLX_CALLBACK TriEnd(void)
-bool SContour::VertexIsEar(int v, Vector normal) {
+{
-    int   va = WRAP(v-1, l.n), vb = WRAP(v  , l.n), vc = WRAP(v+1, l.n);
-    Vector a = l.elem[va].p,    b = l.elem[vb].p,    c = l.elem[vc].p;
-
-    STriMeta meta;
-    ZERO(&meta);
-    STriangle tr = STriangle::From(meta, a, b, c);
-    if(normal.Dot(tr.Normal()) > 0) return false;
-    
-    int i;
-    for(i = 0; i < l.n; i++) {
-        if(i == va) continue;
-        if(i == vb) continue;
-        if(i == vc) continue;
-
-        Vector p = l.elem[i].p;
-        if(p.Equals(tr.a)) continue;
-        if(p.Equals(tr.b)) continue;
-        if(p.Equals(tr.c)) continue;
-
-        if(tr.ContainsPoint(p)) return false;
-    }
-    return true;
 }
-
+static void GLX_CALLBACK TriVertex(Vector *triN)
-void SContour::TriangulateInto(SMesh *m, STriMeta meta, Vector normal) {
+{
-    int i;
+    if(TriVertexCount == 0) {
-
+        Tri1 = *triN;
-    bool odd = false;
-    while(l.n >= 3) {
-        int start, end, incr;
-        if(odd) {
-            start = 0; end = l.n; incr = 1;
-        } else {
-            start = l.n - 1; end = -1; incr = -1;
-        }
-        for(i = start; i != end; i += incr) {
-            if(VertexIsEar(i, normal)) {
-                break;
-            }
-        }
-        if(i == end) {
-            dbp("couldn't find ear!");
-            return;
-        }
-
-        Vector a = l.elem[WRAP(i-1, l.n)].p,
-               b = l.elem[WRAP(i  , l.n)].p,
-               c = l.elem[WRAP(i+1, l.n)].p;
-        m->AddTriangle(meta, c, b, a);
-        l.ClearTags();
-        l.elem[i].tag = 1;
-        l.RemoveTagged();
-
-        odd = !odd;
     }
+    if(TriMode == GL_TRIANGLES) {
+        if((TriVertexCount % 3) == 2) {
+            TriMesh->AddTriangle(
+                TriMeta, TriNormal, TriNMinus2, TriNMinus1, *triN);
+        }
+    } else if(TriMode == GL_TRIANGLE_FAN) {
+        if(TriVertexCount >= 2) {
+            TriMesh->AddTriangle(
+                TriMeta, TriNormal, Tri1, TriNMinus1, *triN);
+        }
+    } else if(TriMode == GL_TRIANGLE_STRIP) {
+        if(TriVertexCount >= 2) {
+            TriMesh->AddTriangle(
+                TriMeta, TriNormal, TriNMinus2, TriNMinus1, *triN);
+        }
+    } else oops();
             
-    l.Clear();
+    TriNMinus2 = TriNMinus1;
+    TriNMinus1 = *triN;
+    TriVertexCount++;
 }
-
 void SPolygon::TriangulateInto(SMesh *m) {
     STriMeta meta;
     ZERO(&meta);
     TriangulateInto(m, meta);
 }
 void SPolygon::TriangulateInto(SMesh *m, STriMeta meta) {
-    FixContourDirections();
+    TriMesh = m;
+    TriNormal = normal;
+    TriMeta = meta;
 
-    int i, j, k;
+    GLUtesselator *gt = gluNewTess();
-    bool *used = (bool *)AllocTemporary(l.n*sizeof(bool));
+    gluTessCallback(gt, GLU_TESS_BEGIN, (glxCallbackFptr *)TriBegin);
-    int *winding = (int *)AllocTemporary(l.n*sizeof(int));
+    gluTessCallback(gt, GLU_TESS_END, (glxCallbackFptr *)TriEnd);
-    bool **contained = (bool **)AllocTemporary(l.n*sizeof(bool *));
+    gluTessCallback(gt, GLU_TESS_VERTEX, (glxCallbackFptr *)TriVertex);
-    for(i = 0; i < l.n; i++) {
-        contained[i] = (bool *)AllocTemporary(l.n*sizeof(bool));
 
-        SContour *sci = &(l.elem[i]);
+    glxTesselatePolygon(gt, this);
-        if(sci->l.n < 1) continue;
-        for(j = 0; j < l.n; j++) {
-            SContour *scj = &(l.elem[j]);
-            if(scj->l.n < 1) continue;
-            if(i == j) {
-                contained[i][j] = true;
-                continue;
-            }
 
-            if(scj->ContainsPointProjdToNormal(normal, sci->l.elem[0].p)) {
+    gluDeleteTess(gt);
-                (winding[i])++;
-                contained[i][j] = true;
-            }
-        }
-    }
-
-    for(;;) {
-        for(i = 0; i < l.n; i++) {
-            if(winding[i] == 0) break;
-        }
-        if(i >= l.n) {
-            // No outer contours left, so we're done
-            break;
-        }
-
-        SContour *outer = &(l.elem[i]);
-        SContour merged;
-        ZERO(&merged);
-
-        SEdgeList extras;
-        ZERO(&extras);
-
-        for(j = 0; j < outer->l.n - 1; j++) {
-            merged.AddPoint(outer->l.elem[j].p);
-        }
-        // If this polygon has holes, then we must merge them in.
-        for(;;) {
-            for(j = 0; j < l.n; j++) {
-                if(used[j]) continue;
-                if(winding[j] != winding[i] + 1) continue;
-                if(!contained[j][i]) continue;
-
-                SContour *inner = &(l.elem[j]);
-
-                int vinner, vouter;
-                if(VisibleVertices(&merged, inner, &extras, &vouter, &vinner)) {
-                    used[j] = true;
-
-                    SEdge se = 
-                        { 0, merged.l.elem[vouter].p, inner->l.elem[vinner].p };
-                    extras.l.Add(&se);
-                    
-                    SContour alt;
-                    ZERO(&alt);
-                    for(k = 0; k <= vouter; k++) {
-                        alt.AddPoint(merged.l.elem[k].p);
-                    }
-                    for(k = 0; k <= inner->l.n - 1; k++) {
-                        int v = WRAP(k + vinner, inner->l.n - 1);
-                        alt.AddPoint(inner->l.elem[v].p);
-                    }
-                    for(k = vouter; k < merged.l.n; k++) {
-                        alt.AddPoint(merged.l.elem[k].p);
-                    }
-                    merged.l.Clear();
-                    merged = alt;
-                    break;
-                }
-            }
-            if(j >= l.n) {
-                break;
-            }
-        }
-
-        merged.TriangulateInto(m, meta, normal);
-        merged.l.Clear();
-        extras.Clear();
-
-        for(j = 0; j < l.n; j++) {
-            if(contained[j][i]) winding[j] -= 2;
-        }
-        used[i] = true;
-    }
 }
 

polygon.h

@@ -78,20 +78,12 @@ public:
     Vector  p;
 };
 
-typedef struct {
-    DWORD   face;
-    int     color;
-} STriMeta;
-
 class SContour {
 public:
-    int             tag;
     SList<SPoint>   l;
 
     void AddPoint(Vector p);
     void MakeEdgesInto(SEdgeList *el);
-    bool VertexIsEar(int v, Vector normal);
-    void TriangulateInto(SMesh *m, STriMeta meta, Vector normal);
     void Reverse(void);
     Vector ComputeNormal(void);
     bool IsClockwiseProjdToNormal(Vector n);
@@ -99,6 +91,11 @@ public:
     bool AllPointsInPlane(Vector n, double d, Vector *notCoplanarAt);
 };
 
+typedef struct {
+    DWORD   face;
+    int     color;
+} STriMeta;
+
 class SPolygon {
 public:
     SList<SContour> l;
@@ -115,9 +112,6 @@ public:
     void Clear(void);
     bool AllPointsInPlane(Vector *notCoplanarAt);
     bool IsEmpty(void);
-    bool IntersectsPolygon(Vector a, Vector b);
-    bool VisibleVertices(SContour *outer, SContour *inner,
-                         SEdgeList *extras, int *vo, int *vi);
     Vector AnyPoint(void);
 };
 

util.cpp

@@ -500,21 +500,6 @@ Vector Vector::AtIntersectionOfPlanes(Vector n1, double d1,
     return (n1.ScaledBy(c1)).Plus(n2.ScaledBy(c2));
 }
 
-bool Vector::LinesIntersect(Vector a0, Vector da, Vector b0, Vector db,
-                            double *ta, double *tb)
-{
-    Vector dn = da.Cross(db); // normal to both
-    if(dn.Magnitude() < 1e-10) return false;
-
-    Vector dna = dn.Cross(da); // normal to dp
-    Vector dnb = dn.Cross(db); // normal to dg
-
-    *tb =  ((a0.Minus(b0)).Dot(dna))/(db.Dot(dna));
-    *ta = -((a0.Minus(b0)).Dot(dnb))/(da.Dot(dnb));
-
-    return true;
-}
-
 Point2d Point2d::Plus(Point2d b) {
     Point2d r;
     r.x = x + b.x;