checkpoint
[anneal.git] / src / edu / berkeley / qfat / Mesh.java
index 5c913c4..45ddf31 100644 (file)
@@ -6,10 +6,13 @@ import javax.swing.*;
 import javax.media.opengl.*;
 import javax.media.opengl.glu.*;
 import edu.berkeley.qfat.geom.*;
+import edu.berkeley.qfat.geom.HasBindingGroup;
 import edu.wlu.cs.levy.CG.KDTree;
 import edu.berkeley.qfat.geom.Point;
 import com.infomatiq.jsi.IntProcedure;
 
+// EDGES RUN COUNTER-CLOCKWISE
+
 public class Mesh implements Iterable<Mesh.T> {
 
     public static final float EPSILON = (float)0.0001;
@@ -18,8 +21,56 @@ public class Mesh implements Iterable<Mesh.T> {
     private RTree<T>         triangles = new RTree<T>();
     private PointSet<Vertex> vertices  = new PointSet<Vertex>();
 
+    public boolean option_wireframe    = false;
+    public boolean option_errorNormals = false;
+    public boolean option_selectable   = true;
+
+    public void render(GL gl, Matrix m) {
+        if (option_wireframe) {
+            gl.glDisable(GL.GL_LIGHTING);
+            gl.glBegin(GL.GL_LINES);
+            gl.glColor3f(1, 1, 1);
+            for (T t : this) {
+                m.times(t.e1().p1.goodp).glVertex(gl);
+                m.times(t.e1().p2.goodp).glVertex(gl);
+                m.times(t.e2().p1.goodp).glVertex(gl);
+                m.times(t.e2().p2.goodp).glVertex(gl);
+                m.times(t.e3().p1.goodp).glVertex(gl);
+                m.times(t.e3().p2.goodp).glVertex(gl);
+            }
+            gl.glEnd();
+            gl.glEnable(GL.GL_LIGHTING);
+            return;
+        }
+        for(T t : this) {
+            gl.glColor4f((float)(0.25+(0.05*t.color)),
+                         (float)(0.25+(0.05*t.color)),
+                         (float)(0.75+(0.05*t.color)),
+                         (float)0.3); 
+            /*
+            if (t.red) {
+            gl.glColor4f((float)(0.75+(0.05*t.color)),
+                         (float)(0.25+(0.05*t.color)),
+                         (float)(0.25+(0.05*t.color)),
+                         (float)0.3); 
+            }
+            */
+            t.glTriangle(gl, m);
+        }
+        if (option_errorNormals)
+            for(T t : this)
+                for(Mesh.Vertex p : new Mesh.Vertex[] { t.v1(), t.v2(), t.v3() }) {
+                    if (p.ok) {
+                        gl.glBegin(GL.GL_LINES);
+                        gl.glColor3f(1, 1, 1);
+                        p.p.glVertex(gl);
+                        p.p.plus(p.norm().times((float)p.error()*10)).glVertex(gl);
+                        gl.glEnd();
+                    }
+                }
+    }
+
     public boolean immutableVertices;
-    public boolean ignorecollision    = false;
     public Mesh    error_against      = null;
     public double  error              = 0;
 
@@ -45,12 +96,14 @@ public class Mesh implements Iterable<Mesh.T> {
             t.e2().dobind();
             t.e3().dobind();
         }
+        System.out.println("rebound!");
     }
 
     public void transform(Matrix m) {
         ArrayList<Vertex> set = new ArrayList<Vertex>();
         for(Vertex v : vertices) set.add(v);
-        for(Vertex v : set) v.transform(m.times(v.p), true);
+        for(Vertex v : set) v.transform(m.times(v.p), true, null);
+        for(Vertex v : set) v.goodp = v.p;
     }
 
     public void rebuild() { /*vertices.rebuild();*/ }
@@ -72,26 +125,165 @@ public class Mesh implements Iterable<Mesh.T> {
     }
 
 
+    public void subdivide() {
+        for (Vertex v : vertices()) v.original = true;
+        HashSet<E> edges = new HashSet<E>();
+        HashSet<E> flip = new HashSet<E>();
+        HashSet<T> tris = new HashSet<T>();
+        int count = 0;
+        for (T t : this) {
+            tris.add(t);
+            edges.add(t.e1());
+            edges.add(t.e2());
+            edges.add(t.e3());
+            count++;
+        }
+        System.out.println("triangles="+count);
+        count = 0;
+        for(E e : edges) {
+            if (e.destroyed || e.shattered) continue;
+            e.shatter().edge = true;
+            for(E ex : (Iterable<E>)e.getBoundPeers()) {
+                Vertex m = nearest(ex.midpoint());
+                m.edge = true;
+                E e3 = ex.p1.getE(m).next;
+                if (e3.p2.original)
+                    flip.add(e3);
+            }
+        }
+
+        int i=0;
+
+        for(E e : flip) {
+            e.flip();
+            System.out.println("flip!");
+            i++;
+        }
+
+        System.out.println("count="+count);
+
+        rebindPoints();
+        HashSet<Vertex> verts = new HashSet<Vertex>();
+        for(Vertex v : vertices()) verts.add(v);
+        for (Vertex v : verts)
+            v.clearWish();
+        for (Vertex v : verts) {
+            if (v.edge) {
+                for(E e = v.e; e!=null; e=e.pair.next==v.e?null:e.pair.next) {
+                    if (e.p2.original) {
+                        v.wish(e.p2);
+                        v.wish(e.p2);
+                        v.wish(e.p2);
+                        v.wish(e.p2);
+                    }
+                }
+                for(E e = v.e; e!=null; e=e.pair.next==v.e?null:e.pair.next) {
+                    for(E e2 = e.p2.e; e2!=null; e2=e2.pair.next==e.p2.e?null:e2.pair.next) {
+                        if (e2.p2.original) {
+                            v.wish(e.p2);
+                        }
+                    }
+                }
+            }
+        }
+        for (Vertex v : verts)
+            v.grantWish();
+        System.out.println("-------------------------------------------------------------------");
+        /*
+        for (Vertex v : verts) {
+            if (v.original) {
+                int n=0;
+                for(E e = v.e; e!=null; e=e.pair.next==v.e?null:e.pair.next) {
+                    n++;
+                    v.wish(e.midpoint());
+                    v.wish(e.midpoint());
+                    v.wish(e.next.pair.t.centroid());
+                }
+                v.avgWish();
+                v.wishes = 3;
+                for(int j=0; j<n-3; j++)
+                    v.wish(v.getPoint());
+            }
+        }
+        for (Vertex v : verts)
+            v.avgWish();
+        for (Vertex v : verts)
+            v.grantWish();
+        */
+    }
+
     // Vertexices //////////////////////////////////////////////////////////////////////////////
 
     /** a vertex in the mesh */
     public final class Vertex extends HasQuadric implements Visitor {
-        public Point p, oldp;
+        public Point p, goodp;
+        public Point oldp;
         E e;                // some edge *leaving* this point
 
-        Matrix binding = Matrix.ONE;
-        Vertex bound_to = this;
-        private boolean good;
+        public boolean original = false;
+        public boolean edge = false;
+        public boolean face = false;
+
+        private int wishes = 0;
+        private Point wish = Point.ZERO;
+        public void clearWish() { wishes = 0; wish = Point.ZERO; }
+        public void wish(HasPoint hp) {
+            Point p = hp.getPoint();
+            wishes++;
+            wish = new Point(wish.x+p.x, wish.y+p.y, wish.z+p.z);
+        }
+        public void grantWish() {
+            for(Vertex v : (Iterable<Vertex>)getBoundPeers()) {
+                if (v==this) continue;
+                if (v.wishes==0) continue;
+                Point p = this.getBindingMatrix(v).times(v.wish.minus(Point.ZERO).div(v.wishes).plus(Point.ZERO));
+                wish = p.minus(Point.ZERO).times(v.wishes).plus(wish);
+                wishes += v.wishes;
+                v.clearWish();
+            }
+            if (wishes==0) return;
+            Vec d = wish.minus(Point.ZERO).div(wishes).plus(Point.ZERO).minus(getPoint());
+            move(d, false);
+            clearWish();
+        }
+        public void avgWish() {
+            if (wishes==0) return;
+            wish = wish.minus(Point.ZERO).div(wishes).plus(Point.ZERO);
+            wishes = 1;
+        }
+
+        private boolean illegal = false;
+
+        public boolean visible = false;
 
         public Point getPoint() { return p; }
         public float error() { return olderror; }
 
         private Vertex(Point p) {
             this.p = p;
+            this.goodp = p;
+            this.oldp = p;
             if (vertices.get(p) != null) throw new Error();
             vertices.add(this);
         }
 
+        public void reinsert() {
+            vertices.remove(this);
+            vertices.add(this);
+            for(E e = this.e; e!=null; e=e.pair.next==this.e?null:e.pair.next) e.t.reinsert();
+        }
+
+        // the average of all adjacent points
+        public Point recenter() {
+            int count = 0;
+            Vec vec = Vec.ZERO;
+            for(E e = this.e; e!=null; e=e.pair.next==this.e?null:e.pair.next) {
+                vec = vec.plus(e.getOther(this).getPoint().minus(Point.ZERO));
+                count++;
+            }
+            return Point.ZERO.plus(vec.div(count));
+        }
+
         public float olderror = 0;
         public void setError(float nerror) {
             error -= olderror;
@@ -99,6 +291,41 @@ public class Mesh implements Iterable<Mesh.T> {
             error += olderror;
         }
 
+        /*
+        public Vertex hack(GL gl, Point mouse) {
+            double dist = Double.MAX_VALUE;
+            Vertex cur = null;
+            for(E e = this.e; e!=null; e=e.pair.next==this.e?null:e.pair.next) {
+                Vertex v = e.getOther(this);
+                double dist2 = v.getPoint().glProject(gl).distance(mouse);
+                if ((cur==null || dist2 < dist) && v.visible) {
+                    dist = dist2;
+                    cur = v;
+                }
+            }
+            return cur;
+        }
+        */
+
+        public float averageTriangleArea() {
+            int count = 0;
+            float ret = 0;
+            for(E e = this.e; e!=null; e=e.pair.next==this.e?null:e.pair.next) {
+                ret += e.t.area();
+                count++;
+            }
+            return ret/count;
+        }
+        public float averageEdgeLength() {
+            int count = 0;
+            float ret = 0;
+            for(E e = this.e; e!=null; e=e.pair.next==this.e?null:e.pair.next) {
+                ret += e.length();
+                count++;
+            }
+            return ret/count;
+        }
+
         public Matrix _recomputeFundamentalQuadric() {
             Matrix m = Matrix.ZERO;
             int count = 0;
@@ -106,64 +333,163 @@ public class Mesh implements Iterable<Mesh.T> {
                 m = m.plus(e.t.norm().fundamentalQuadric(e.t.centroid()));
                 count++;
             }
+            if (count > 0) {
+                m = m.plus(norm().fundamentalQuadric(this.p).times(count));
+                count *= 2;
+            }
             return m.times(1/(float)count);
         }
 
         public HasQuadric nearest() { return error_against==null ? null : error_against.vertices.nearest(p, this); }
         public void computeError() {
+            if (error_against==null) return;
+            if (nearest_in_other_mesh == null && nearest()==null) return;
             float nerror =
-                quadric_count != 0
-                ? (quadric.preAndPostMultiply(p) * 100) / quadric_count
-                : nearest_in_other_mesh != null
-                ? nearest_in_other_mesh.fundamentalQuadric().preAndPostMultiply(p) * 100 * 10
-                : error_against != null
-                ? nearest().fundamentalQuadric().preAndPostMultiply(p) * 100 * 10
-                : 0;
+                nearest_in_other_mesh != null
+                ? nearest_in_other_mesh.fundamentalQuadric().preAndPostMultiply(p)
+                : nearest().fundamentalQuadric().preAndPostMultiply(p);
+            if (quadric_count != 0)
+                nerror = (nerror + quadric.preAndPostMultiply(p))/(quadric_count+1);
+
+            if (!immutableVertices && quadric_count == 0) {
+                //nerror = Math.max(nerror, 0.4f);
+                //nerror *= 2;
+            }
+            //System.out.println(nerror);
             for(E e = this.e; e!=null; e=e.pair.next==this.e?null:e.pair.next) {
-                double ang = Math.abs(e.crossAngle());
+                double ang = e.dihedralAngle();
                 if (ang > Math.PI) throw new Error();
+                if (ang < -Math.PI) throw new Error();
                 float minangle = (float)(Math.PI * 0.8);
+                //nerror += ((ang / Math.PI)*(ang/Math.PI)) * e.length() * 0.05;
+
+                nerror += (1-e.t.quality())*0.0001;
                 if (ang > minangle) nerror += (ang - minangle);
+
+                //System.out.println(((ang / Math.PI)*(ang/Math.PI)) * 0.000001);
+                /*
+                if (e.t.aspect() < 0.2) {
+                    nerror += (0.2-e.t.aspect()) * 10;
+                }
+                */
             }
+            if (!immutableVertices) {
+                Vertex n = (Vertex)nearest();
+                float d = norm().dot(n.norm());
+                if (d > 1 || d < -1) throw new Error();
+                if (d >= 0) {
+                    nerror *= (2.0f - d);
+                } else {
+                    nerror += 0.0003 * (2.0f + d);
+                    nerror *= (2.0f + d);
+                }
+            }
+
             setError(nerror);
         }
 
+        public boolean move(Vec vv, boolean ignoreProblems) {
+
+            boolean good = true;
+
+            //     t1' = M * t1
+            //     t2' = t2.getMatrix(t1) * t1'
+            //     t2' = t2.getMatrix(t1) * M * t1
+            //     t1 =     t1.getMatrix(t2) * t2
+            // M * t1 = M * t1.getMatrix(t2) * t2
+
+            if (bindingGroup!=null && this != bindingGroup.getMaster()) {
+                Matrix m2 = getBindingMatrix(bindingGroup.getMaster());
+                Vec v2 = m2.times(vv.plus(getPoint())).minus(m2.times(getPoint()));
+                return ((Vertex)bindingGroup.getMaster()).move(v2, ignoreProblems);
+            }
+
+            Point op = this.p;
+            Point pp = vv.plus(getPoint());
+            if (bindingGroup != null) {
+                /*
+                for(int i=0; i<20 ; i++) {
+                    Point v2 = getConstraint().times(pp);
+                    pp = pp.midpoint(v2);
+                    //System.out.println(m.minus(m2));
+                }
+            */
+                //pp = getConstraint().times(pp);
+            }
+            //pp = pp.minus(op).norm().times(vv.mag()).plus(op);
+            ok = false;
+            Point pt = pp;
+            for(Vertex v : (Iterable<Vertex>)getBoundPeers()) {
+                Point pt2 = v.getBindingMatrix(this).times(pt);
+                /*
+                if (Math.abs( v.p.minus(pt2).mag() / pt.minus(op).mag() ) > 5)
+                    throw new Error(v.p+" "+pt2+"\n"+op+" "+pt+"\n"+v.getBindingMatrix(this));
+                if (Math.abs( v.p.minus(pt2).mag() / pt.minus(op).mag() ) < 1/5) throw new Error();
+                */
+                good &= v.transform(pt2, ignoreProblems, v.getBindingMatrix(this));
+            }
+
+            if (!good && !ignoreProblems) {
+                for(Vertex v : (Iterable<Vertex>)getBoundPeers()) 
+                    v.transform(v.oldp, true, null);
+            }
+
+            for(Vertex v : (Iterable<Vertex>)getBoundPeers())
+                v.recomputeFundamentalQuadricIfNeighborChanged();
+            for(Vertex v : (Iterable<Vertex>)getBoundPeers())
+                v.reComputeErrorAround();
+            ok = true;
+            return good;
+        }
+        public boolean ok = true;
+
         /** does NOT update bound pairs! */
-        private boolean transform(Point newp, boolean ignoreProblems) {
+        private boolean transform(Point newp, boolean ignoreProblems, Matrix yes) {
             this.oldp = this.p;
             if (immutableVertices) throw new Error();
 
             unApplyQuadricToNeighbor();
 
-            if (vertices.get(this.p)==null) throw new Error();
-            vertices.remove(this);
-            for(E e = this.e; e!=null; e=e.pair.next==this.e?null:e.pair.next)
-                if (e.t != null) e.t.removeFromRTree();
-            this.p = newp;
-            for(E e = this.e; e!=null; e=e.pair.next==this.e?null:e.pair.next)
-                if (e.t != null) e.t.addToRTree();
-            vertices.add(this);
+            boolean illegalbefore = illegal;
+            illegal = false;
+            /*
+            if (this.p.minus(newp).mag() > 0.1 && !ignoreProblems) {
+                try {
+                    throw new Exception(""+this.p.minus(newp).mag()+" "+ignoreProblems+" "+yes);
+                } catch(Exception e) {
+                    e.printStackTrace();
+                }
+                illegal = true;
+            }
+            */
 
+            this.p = newp;
+            reinsert();
             applyQuadricToNeighbor();
 
-            good = true;
-
-            if (!ignoreProblems)
-                for(E e = this.e; e!=null; e=e.pair.next==this.e?null:e.pair.next) {
-                    if (Math.abs(e.crossAngle()) > (Math.PI * 0.9) || Math.abs(e.next.crossAngle()) > (Math.PI * 0.9)) good = false;
-                    if (e.t.aspect() < 0.1) good = false;
-                    e.p2.quadricStale = true;
-                }
-
-            if (!ignorecollision && !ignoreProblems && good)
-                triangles.range(oldp, this.p, (Visitor<T>)this);
+            if (!ignoreProblems) {
+                checkLegality();
+            }
+            for(E e = this.e; e!=null; e=e.pair.next==this.e?null:e.pair.next)
+                e.p2.quadricStale = true;
+            return !illegal || (illegalbefore && illegal);
+        } 
 
-            return good;
+        public void checkLegality() {
+            /*
+            for(E e = this.e; e!=null; e=e.pair.next==this.e?null:e.pair.next) {
+                if (Math.abs(e.dihedralAngle()) > (Math.PI * 0.9) ||
+                    Math.abs(e.next.dihedralAngle()) > (Math.PI * 0.9)) illegal = true;
+                if (e.t.aspect() < 0.2) illegal = true;
+            }
+            */
+            if (!illegal) triangles.range(oldp, this.p, (Visitor<T>)this);
         }
 
         public void reComputeErrorAround() {
             reComputeError();
-            if (nearest_in_other_mesh != null) nearest_in_other_mesh.reComputeError();
+            if (nearest_in_other_mesh != null)
+                nearest_in_other_mesh.reComputeError();
             for(E e = this.e; e!=null; e=e.pair.next==this.e?null:e.pair.next)
                 e.p2.reComputeError();
         }
@@ -172,28 +498,19 @@ public class Mesh implements Iterable<Mesh.T> {
             if (o instanceof Vertex)
                 return ((Vertex)o).e != null && ((Vertex)o).norm().dot(Vertex.this.norm()) >= 0;
             T t = (T)o;
-            if (!good) return false;
+            if (illegal) return false;
             for(E e = Vertex.this.e; e!=null; e=e.pair.next==Vertex.this.e?null:e.pair.next) {
-                if (!t.has(e.p1) && !t.has(e.p2) && e.intersects(t)) { good = false; }
+                if (!t.has(e.p1) && !t.has(e.p2) && e.intersects(t)) { illegal = true; }
                 if (e.t != null) {
-                    if (!e.t.has(t.e1().p1) && !e.t.has(t.e1().p2) && t.e1().intersects(e.t)) { good = false; }
-                    if (!e.t.has(t.e2().p1) && !e.t.has(t.e2().p2) && t.e2().intersects(e.t)) { good = false; }
-                    if (!e.t.has(t.e3().p1) && !e.t.has(t.e3().p2) && t.e3().intersects(e.t)) { good = false; }
+                    if (!e.t.has(t.e1().p1) && !e.t.has(t.e1().p2) && t.e1().intersects(e.t)) { illegal = true; }
+                    if (!e.t.has(t.e2().p1) && !e.t.has(t.e2().p2) && t.e2().intersects(e.t)) { illegal = true; }
+                    if (!e.t.has(t.e3().p1) && !e.t.has(t.e3().p2) && t.e3().intersects(e.t)) { illegal = true; }
                 }
             }
-            return good;
-        }
-
-        public boolean move(Matrix m, boolean ignoreProblems) {
-            boolean good = true;
-            for(Vertex p = this; p != null; p = (p.bound_to==this)?null:p.bound_to)
-                good &= p.transform(m.times(p.p), ignoreProblems);
-            for(Vertex p = this; p != null; p = (p.bound_to==this)?null:p.bound_to)
-                if (good)  p.reComputeErrorAround();
-                else       p.transform(p.oldp, true);
-            return good;
+            return !illegal;
         }
 
+        public E getEdge() { return e; }
         public E getFreeIncident() {
             E ret = getFreeIncident(e, e);
             if (ret != null) return ret;
@@ -215,8 +532,14 @@ public class Mesh implements Iterable<Mesh.T> {
             return getE(v);
         }
         public E getE(Vertex p2) {
-            for(E e = this.e; e!=null; e=e.pair.next==this.e?null:e.pair.next)
+            if (this.e!=null && this!=this.e.p1 && this!=this.e.p2) throw new RuntimeException();
+            int i=0;
+            for(E e = this.e; e!=null; e=e.pair.next==this.e?null:e.pair.next) {
                 if (e.p1 == this && e.p2 == p2) return e;
+                i++;
+                e.sanity();
+                if (e.destroyed) throw new RuntimeException("fark " + i + " " + e.prev + " " + (e.prev.next==e) + " " + e.prev.destroyed);
+            }
             return null;
         }
 
@@ -232,112 +555,195 @@ public class Mesh implements Iterable<Mesh.T> {
             return norm.norm();
         }
 
-        public boolean isBoundTo(Vertex p) {
-            for(Vertex px = p; px!=null; px=(px.bound_to==p?null:px.bound_to))
-                if (px==this)
-                    return true;
-            return false;
-        }
-
-        public void unbind() { bound_to = this; binding = Matrix.ONE; }
-        public void bind(Vertex p) { bind(p, Matrix.ONE); }
-        public void bind(Vertex p, Matrix binding) {
-            if (isBoundTo(p)) return;
-            Vertex temp_bound_to = p.bound_to;
-            Matrix temp_binding = p.binding;
-            p.bound_to = this.bound_to;
-            p.binding = binding.times(this.binding); // FIXME: may have order wrong here
-            this.bound_to = temp_bound_to;
-            this.binding = temp_binding.times(temp_binding); // FIXME: may have order wrong here
-        }
+        public void bindTo(Vertex p) { bindTo(Matrix.ONE, p); }
     }
 
-    public class BindingGroup {
-        private HashSet<E> set = new HashSet<E>();
-        public BindingGroup bind_others;
-        public BindingGroup other() { return bind_others; }
-        public BindingGroup(BindingGroup bind_others) { this.bind_others = bind_others; }
-        public BindingGroup() { this.bind_others = new BindingGroup(this); }
-        public BindingGroup(E e) { this(); set.add(e); }
-        public void add(E e) {
-            if (set.contains(e)) return;
-            set.add(e);
-            BindingGroup e_bind_peers = e.bind_peers;
-            BindingGroup e_bind_to    = e.bind_to;
-            e.bind_peers = this;
-            e.bind_to    = bind_others;
-            for (E epeer  : e_bind_peers.set) add(epeer);
-            for (E eother : e_bind_to.set)    bind_others.add(eother);
-
-            for(E eother : bind_others.set) {
-                if (e.next.bind_to.set.contains(eother.prev)) {
-                    e.next.next.bindEdge(eother.prev.prev);
-                }
-                if (e.prev.bind_to.set.contains(eother.next)) {
-                    e.prev.prev.bindEdge(eother.next.next);
-                }
-            }
-
-        }
-        public void dobind(E e) {
-            for(E ebound : set) {
-                e.p1.bind(ebound.p2);
-                e.p2.bind(ebound.p1);
-            }
-        }
-        public void shatter(BindingGroup bg1, BindingGroup bg2) {
-            for(E e : set) {
-                e.shatter(e.midpoint(), bg1, bg2);
-            }
-        }
-    }
 
     /** [UNIQUE] an edge */
-    public final class E implements Comparable<E> {
+    public final class E extends HasBindingGroup implements Comparable<E> {
+
+        public void sanity() {
+            if (destroyed) return;
+            if (pair!=null && (pair.p1!=p2 || pair.p2!=p1)) throw new RuntimeException();
+            if (next!=null && next.p1!=p2) throw new RuntimeException();
+            if (prev!=null && prev.p2!=p1) throw new RuntimeException();
+        }
 
         public final Vertex p1, p2;
         T t;     // triangle to our "left"
         E prev;  // previous half-edge
         E next;  // next half-edge
         E pair;  // partner half-edge
-        public BindingGroup bind_peers  = new BindingGroup(this);
-        public BindingGroup bind_to     = bind_peers.other();
         boolean shattered = false;
 
         public boolean intersects(T t) { return t.intersects(p1.p, p2.p); }
-        public float comparator() {
+
+        public Segment getSegment() { return new Segment(p1.getPoint(), p2.getPoint()); }
+
+        public void flip() {
+            // FIXME: coplanarity check needed
+            if (destroyed) return;
+            for (E e : (Iterable<E>)getBoundPeers()) {
+                if (!e.pair.isBoundTo(pair)) throw new RuntimeException("cannot flip!");
+            }
+            Vertex v1 = t.getOtherVertex(this);
+            Vertex v2 = pair.t.getOtherVertex(pair);
+            destroy();
+            pair.destroy();
+            T t1 = newT(v1, v2, p2);
+            T t2 = newT(v2, v1, p1);
+            t1.e1().sanity();
+            t1.e2().sanity();
+            t1.e3().sanity();
+            t2.e1().sanity();
+            t2.e2().sanity();
+            t2.e3().sanity();
+
+            for (E e : (Iterable<E>)getBoundPeers()) {
+                if (e==this) continue;
+                if (e.destroyed) continue;
+                Vertex v1e = e.t.getOtherVertex(e);
+                Vertex v2e = e.pair.t.getOtherVertex(e.pair);
+                e.destroy();
+                e.pair.destroy();
+                if (v1e.getE(v2e)!=null) throw new RuntimeException();
+                newT(v1e, v2e, e.p2).red = true;
+                newT(v2e, v1e, e.p1).red = true;
+                v2e.getE(v1e).bindTo(e.getBindingMatrix(this), v1.getE(v2));
+                v1e.getE(v2e).bindTo(e.pair.getBindingMatrix(this.pair), v2.getE(v1));
+            }
+
+        }
+
+        public void bindingGroupChanged(edu.berkeley.qfat.geom.BindingGroup newBindingGroup_) {
+
+            edu.berkeley.qfat.geom.BindingGroup<E> newBindingGroup =
+                (edu.berkeley.qfat.geom.BindingGroup<E>)newBindingGroup_;
+            if (newBindingGroup==null) return;
+            if (this==newBindingGroup.getMaster()) return;
+            HashSet<E> nbg = new HashSet<E>();
+            for(E eother : (Iterable<E>)newBindingGroup) nbg.add(eother);
+            for(E eother : nbg) {
+                if (next==null || prev==null) continue;
+                if (eother.next==null || eother.prev==null) continue;
+
+                if (next.isBoundTo(eother.pair.prev.pair) && !prev.isBoundTo(eother.pair.next.pair))
+                    prev.bindTo(next.getBindingMatrix(eother.pair.prev.pair), eother.pair.next.pair);
+                if (!next.isBoundTo(eother.pair.prev.pair) && prev.isBoundTo(eother.pair.next.pair))
+                    next.bindTo(prev.getBindingMatrix(eother.pair.next.pair), eother.pair.prev.pair);
+
+                /*
+                if (next.isBoundTo(eother.prev) && !prev.isBoundTo(eother.next))
+                    prev.bindTo(next.getBindingMatrix(eother.prev), eother.next);
+                if (!next.isBoundTo(eother.prev) && prev.isBoundTo(eother.next))
+                    next.bindTo(prev.getBindingMatrix(eother.next), eother.prev);
+                */
+                if (next.isBoundTo(eother.next) && !prev.isBoundTo(eother.prev))
+                    prev.bindTo(next.getBindingMatrix(eother.next), eother.prev);
+                if (!next.isBoundTo(eother.next) && prev.isBoundTo(eother.prev))
+                    next.bindTo(prev.getBindingMatrix(eother.prev), eother.next);
+            }
+
+        }
+
+        public float stretchRatio() {
             Vertex nearest = error_against.nearest(midpoint());
-            return (float)Math.max(length(), midpoint().distance(nearest.p));
+            float nearest_distance = midpoint().distance(nearest.p);
+            float other_distance =
+                (p1.p.distance(error_against.nearest(p1.p).p)+
+                 p2.p.distance(error_against.nearest(p2.p).p))/2;
+            return nearest_distance/other_distance;
+        }
+        public float comparator() {
+            return length();
         }
         public int compareTo(E e) {
             return e.comparator() > comparator() ? 1 : -1;
         }
-        public void bindEdge(E e) { bind_to.add(e); }
-        public void dobind() { bind_to.dobind(this); }
+        public void bindEdge(E e, Matrix m) {
+            _bindEdge(e, m);
+            pair._bindEdge(e.pair, m);
+        }
+        public void _bindEdge(E e, Matrix m) {
+            e = e.pair;
+            /*
+            //assumes edges are identical length at binding time
+            Vec reflectionPlaneNormal = e.p2.p.minus(e.p1.p).norm();
+            float a = reflectionPlaneNormal.x;
+            float b = reflectionPlaneNormal.y;
+            float c = reflectionPlaneNormal.z;
+            Matrix reflectionMatrix =
+                new Matrix( 1-2*a*a,  -2*a*b,  -2*a*c, 0,
+                            -2*a*b,  1-2*b*b,  -2*b*c, 0,
+                            -2*a*c,   -2*b*c, 1-2*c*c, 0,
+                            0,       0,       0,       1);
+            m = m.times(Matrix.translate(e.midpoint().minus(Point.ORIGIN))
+                        .times(reflectionMatrix)
+                        .times(Matrix.translate(Point.ORIGIN.minus(e.midpoint()))));
+            System.out.println(reflectionPlaneNormal);
+            System.out.println("  " + p1.p + " " + m.times(e.p1.p));
+            System.out.println("  " + p2.p + " " + m.times(e.p2.p));
+            */
+            /*
+            if (m.times(e.p1.p).minus(p1.p).mag() > EPSILON) throw new Error();
+            if (m.times(e.p2.p).minus(p2.p).mag() > EPSILON) throw new Error();
+            */
+            this.bindTo(m, e);
+        }
+        
+        public void dobind() {
+            for(E e : (Iterable<E>)getBoundPeers()) {
+                if (e==this) continue;
+                p1.bindTo(getBindingMatrix(e), e.p1);
+                p2.bindTo(getBindingMatrix(e), e.p2);
+                e.p1.setConstraint(getConstraint());
+                e.p2.setConstraint(getConstraint());
+            }
+        }
 
-        public Point shatter() { return shatter(midpoint(), null, null); }
-        public Point shatter(Point mid, BindingGroup bg1, BindingGroup bg2) {
-            if (shattered || destroyed) return mid;
+        public Vertex shatter() {
+            if (shattered || destroyed) return nearest(midpoint());
             shattered = true;
-
-            Vertex r = next.p2;
-            E next = this.next;
-            E prev = this.prev;
-
-            int old_colorclass = t==null ? 0 : t.colorclass;
-            if (bg1==null) bg1 = new BindingGroup();
-            if (bg2==null) bg2 = new BindingGroup();
-            BindingGroup old_bind_to = bind_to;
-            bind_peers.shatter(bg1, bg2);
-            old_bind_to.shatter(bg2.other(), bg1.other());
-            pair.shatter();
-            destroy();
-
-            newT(r.p, p1.p, mid, null, old_colorclass);
-            newT(r.p, mid, p2.p, null, old_colorclass);
-            bg1.add(p1.getE(mid));
-            bg2.add(p2.getE(mid).pair);
-            return mid;
+            E first = null;
+            E firste = null;
+            E firstx = null;
+            E firstq = null;
+            for(E e : (Iterable<E>)getBoundPeers()) {
+                E enext = e.next;
+                E eprev = e.prev;
+                E pnext = e.pair.next;
+                E pprev = e.pair.prev;
+                Point mid = e.midpoint();
+                Vertex r = e.next.p2;
+                Vertex l = e.pair.next.p2;
+                if (!e.destroyed) {
+                    e.destroy();
+                    e.pair.destroy();
+                    newT(r.p, e.p1.p, mid,    null, 0);
+                    newT(r.p, mid,    e.p2.p, null, 0);
+                    newT(l.p, mid,    e.p1.p, null, 0);
+                    newT(l.p, e.p2.p, mid,    null, 0);
+                }
+            }
+            for(E e : (Iterable<E>)getBoundPeers()) {
+                Point mid = e.midpoint();
+                if (first==null) {
+                    first = e.p1.getE(mid);
+                    firste = e;
+                    firstx = e.pair;
+                    firstq = e.p2.getE(mid).pair;
+                    continue;
+                }
+                e.p1.getE(mid).          bindTo(e.getBindingMatrix(firste), first);
+                e.p1.getE(mid).pair.     bindTo(e.getBindingMatrix(firste), first.pair);
+                e.p2.getE(mid).pair.     bindTo(e.getBindingMatrix(firste), firstq);
+                e.p2.getE(mid).pair.pair.bindTo(e.getBindingMatrix(firste), firstq.pair);
+            }
+            /*
+            first.setConstraint(firste.getConstraint());
+            firstq.setConstraint(firste.getConstraint());
+            */
+            return nearest(midpoint());
         }
 
         public boolean destroyed = false;
@@ -362,23 +768,43 @@ public class Mesh implements Iterable<Mesh.T> {
             pair.next.t = null;
             pair.prev.t = null;
 
-            this.bind_to = null;
-            pair.bind_to = null;
-            this.bind_peers = null;
-            pair.bind_peers = null;
             pair.prev.next = next;
             next.prev = pair.prev;
             prev.next = pair.next;
-            pair.next = prev;
-            if (p1.e == this) p1.e = prev.next;
-            if (pair.p1.e == pair) pair.p1.e = pair.prev.next;
+            pair.next.prev = prev;
+
+            if (p1.e == this) p1.e = pair.next;
+            if (pair.p1.e == pair) pair.p1.e = next;
+
+            if (p2.e == this) throw new RuntimeException();
+            if (pair.p2.e == pair) throw new RuntimeException();
+
+            /*
+            next = pair;
+            prev = pair;
+            pair.next = this;
+            pair.prev = this;
+            */
+
+            /*
+            pair.prev = null;
+            pair.next = null;
+            next = null;
+            prev = null;
+            */
+
+            /*
+            sanity();
+            next.sanity();
+            prev.sanity();
+            pair.sanity();
+            */
         }
 
         private void sync() {
             this.prev.next = this;
             this.next.prev = this;
             this.pair.pair = this;
-            bind_peers.add(this);
             if (this.next.p1 != p2) throw new Error();
             if (this.prev.p2 != p1) throw new Error();
             if (this.p1.e == null) this.p1.e = this;
@@ -388,10 +814,15 @@ public class Mesh implements Iterable<Mesh.T> {
 
         public T makeT(int colorclass) { return t==null ? (t = new T(this, colorclass)) : t; }
 
-        public double crossAngle() {
+        public double dihedralAngle() {
             Vec v1 = t.norm().times(-1);
             Vec v2 = pair.t.norm().times(-1);
-            return Math.acos(v1.norm().dot(v2.norm()));
+            double prod = v1.norm().dot(v2.norm());
+            prod = Math.min(1,prod);
+            prod = Math.max(-1,prod);
+            double ret = Math.acos(prod);
+            if (Double.isNaN(ret)) throw new Error("nan! " + prod);
+            return ret;
         }
 
         /** angle between this half-edge and the next */
@@ -401,10 +832,16 @@ public class Mesh implements Iterable<Mesh.T> {
             return Math.acos(v1.norm().dot(v2.norm()));
         }
 
+        public Vertex getOther(Vertex v) {
+            if (this.p1 == v) return p2;
+            if (this.p2 == v) return p1;
+            throw new Error();
+        }
+
         public void makeAdjacent(E e) {
             if (this.next == e) return;
-            if (p2 != e.p1) throw new Error("cannot make adjacent -- no shared vertex");
-            if (t != null || e.t != null) throw new Error("cannot make adjacent -- edges not both free");
+            if (p2 != e.p1) throw new Error("cannot make adjacent -- no shared vertex: " + this + " " + e);
+            if (t != null || e.t != null) throw new Error("cannot make adjacent -- edges not both free " + t + " " + e.t);
 
             E freeIncident = p2.getFreeIncident(e, this);
 
@@ -441,6 +878,7 @@ public class Mesh implements Iterable<Mesh.T> {
             this.p1 = prev.p2;
             this.p2 = p2;
             this.prev = prev;
+            if (prev.destroyed) throw new RuntimeException();
             if (p2.getE(p1) != null) throw new Error();
             if (p2.e==null) {
                 this.next = this.pair = new E(this, this, prev.next);
@@ -460,6 +898,7 @@ public class Mesh implements Iterable<Mesh.T> {
         public E(E prev, E pair, E next) {
             this.p1 = prev.p2;
             this.p2 = next.p1;
+            if (prev.destroyed) throw new RuntimeException();
             this.prev = prev;
             this.next = next;
             this.pair = pair;
@@ -485,7 +924,25 @@ public class Mesh implements Iterable<Mesh.T> {
         if (v2 != null) return new E(v2.getFreeIncident(), p1).pair;
         return new E(p1, p2);
     }
+    public boolean coalesce = false;
+    private static float round(float f) {
+        return Math.round(f*1000)/1000f;
+    }
+    public T newT(HasPoint p1, HasPoint p2, HasPoint p3) {
+        return newT(p1.getPoint(), p2.getPoint(), p3.getPoint(), null, 0);
+    }
     public T newT(Point p1, Point p2, Point p3, Vec norm, int colorclass) {
+        if (coalesce) {
+
+            for(Vertex v : vertices) { if (p1.distance(v.p) < EPSILON) { p1 = v.p; break; } }
+            for(Vertex v : vertices) { if (p2.distance(v.p) < EPSILON) { p2 = v.p; break; } }
+            for(Vertex v : vertices) { if (p3.distance(v.p) < EPSILON) { p3 = v.p; break; } }
+            /*
+            p1 = new Point(round(p1.x), round(p1.y), round(p1.z));
+            p2 = new Point(round(p2.x), round(p2.y), round(p2.z));
+            p3 = new Point(round(p3.x), round(p3.y), round(p3.z));
+            */
+        }
         if (norm != null) {
             Vec norm2 = p3.minus(p1).cross(p2.minus(p1));
             float dot = norm.dot(norm2);
@@ -507,17 +964,121 @@ public class Mesh implements Iterable<Mesh.T> {
         return ret;
     }
 
-
+    private int max_serial = 0;
     /** [UNIQUE] a triangle (face) */
     public final class T extends Triangle {
         public final E e1;
         public final int color;
         public final int colorclass;
 
-        public void removeFromRTree() { triangles.remove(this); }
-        public void addToRTree() { triangles.insert(this); }
+        public boolean red = false;
+        public boolean old = false;
+
+        public final int serial = max_serial++;
+        public boolean occluded;
+
+        public Point shatter() {
+            if (destroyed) return null;
+            E e = e1();
+            
+            HashSet<E> forward = new HashSet<E>();
+            HashSet<E> backward = new HashSet<E>();
+            HashSet<E> both = new HashSet<E>();
+
+            for(E eb : (Iterable<E>)e.getBoundPeers()) {
+                if (eb==e) continue;
+                if (eb.next.isBoundTo(e.next) && eb.prev.isBoundTo(e.prev)) {
+                    forward.add(eb);
+                    both.add(eb);
+                }
+                if (eb.pair.next.pair.isBoundTo(e.prev) && eb.pair.prev.pair.isBoundTo(e.next)) {
+                    backward.add(eb.pair);
+                    both.add(eb.pair);
+                }
+            }
+
+            Vertex v1 = e.t.v1();
+            Vertex v2 = e.t.v2();
+            Vertex v3 = e.t.v3();
+            Point c = e.t.centroid();
+            E e_next = e.next;
+            E e_prev = e.prev;
+            e.t.destroy();
+            newT(v1, v2, c);
+            newT(c,  v2, v3);
+            newT(v3, v1, c);
+
+            // FIXME: forward too
+            for(E ex : backward) {
+                Vertex v1x = ex.t.v1();
+                Vertex v2x = ex.t.v2();
+                Vertex v3x = ex.t.v3();
+                Point cx = ex.t.centroid();
+                E ex_next = ex.next;
+                E ex_prev = ex.prev;
+                ex.t.destroy();
+                newT(v1x, v2x, cx);
+                newT(cx,  v2x, v3x);
+                newT(v3x, v1x, cx);
+
+                // FIXME: i have no idea if this is right
+                e.next.bindTo(e.getBindingMatrix(ex.pair), ex.prev);
+                e.prev.bindTo(e.getBindingMatrix(ex.pair), ex.next);
+                e.next.pair.bindTo(e.getBindingMatrix(ex.pair), ex.prev.pair);
+                e.prev.pair.bindTo(e.getBindingMatrix(ex.pair), ex.next.pair);
+
+                e_next.next.bindTo(e_next.getBindingMatrix(ex_prev.pair), ex_prev.prev.pair);
+                e_next.prev.bindTo(e_next.getBindingMatrix(ex_prev.pair), ex_prev.next.pair);
+
+                e_prev.next.bindTo(e_prev.getBindingMatrix(ex_next.pair), ex_next.prev.pair);
+                e_prev.prev.bindTo(e_prev.getBindingMatrix(ex_next.pair), ex_next.next.pair);
+            }
+
+            /*
+
+            E first = null;
+            E firste = null;
+            E firstx = null;
+            E firstq = null;
+            for(E e : (Iterable<E>)getBoundPeers()) {
+                E enext = e.next;
+                E eprev = e.prev;
+                E pnext = e.pair.next;
+                E pprev = e.pair.prev;
+                Point mid = e.midpoint();
+                Vertex r = e.next.p2;
+                Vertex l = e.pair.next.p2;
+                if (!e.destroyed) {
+                    e.destroy();
+                    e.pair.destroy();
+                    newT(r.p, e.p1.p, mid,    null, 0);
+                    newT(r.p, mid,    e.p2.p, null, 0);
+                    newT(l.p, mid,    e.p1.p, null, 0);
+                    newT(l.p, e.p2.p, mid,    null, 0);
+                }
+            }
+            for(E e : (Iterable<E>)getBoundPeers()) {
+                Point mid = e.midpoint();
+                if (first==null) {
+                    first = e.p1.getE(mid);
+                    firste = e;
+                    firstx = e.pair;
+                    firstq = e.p2.getE(mid).pair;
+                    continue;
+                }
+                e.p1.getE(mid).          bindTo(e.getBindingMatrix(firste), first);
+                e.p1.getE(mid).pair.     bindTo(e.getBindingMatrix(firste), first.pair);
+                e.p2.getE(mid).pair.     bindTo(e.getBindingMatrix(firste), firstq);
+                e.p2.getE(mid).pair.pair.bindTo(e.getBindingMatrix(firste), firstq.pair);
+            }
+            */
+            /*
+            first.setConstraint(firste.getConstraint());
+            firstq.setConstraint(firste.getConstraint());
+            */
+            return null;
+        }
 
-        public void destroy() { triangles.remove(this); }
 
         T(E e1, int colorclass) {
             this.e1 = e1;
@@ -556,12 +1117,51 @@ public class Mesh implements Iterable<Mesh.T> {
         public boolean hasE(E e) { return e1==e || e1.next==e || e1.prev==e; }
         public boolean has(Vertex v) { return v1()==v || v2()==v || v3()==v; }
 
+        public Vertex getOtherVertex(E e) {
+            if (!hasE(e)) throw new RuntimeException();
+            if (!e.has(v1())) return v1();
+            if (!e.has(v2())) return v2();
+            if (!e.has(v3())) return v3();
+            throw new RuntimeException();
+        }
+
+        public void removeFromRTree() { triangles.remove(this); }
+        public void addToRTree() { triangles.insert(this); }
+        public void destroy() {
+            if (e1 != null) {
+                e1.t = null;
+                e1.next.t = null;
+                e1.prev.t = null;
+            }
+            triangles.remove(this);
+            destroyed = true;
+        }
+        public void reinsert() { triangles.remove(this); triangles.add(this); }
+
+        private boolean destroyed = false;
+        public boolean destroyed() { return destroyed; }
+
         public boolean shouldBeDrawn() {
-            if (e1().bind_to.set.size() == 0) return false;
-            if (e2().bind_to.set.size() == 0) return false;
-            if (e3().bind_to.set.size() == 0) return false;
+
+            if (e1().bindingGroupSize() <= 1) return false;
+            if (e2().bindingGroupSize() <= 1) return false;
+            if (e3().bindingGroupSize() <= 1) return false;
+
             return true;
         }
 
+        public void glTriangle(GL gl, Matrix m) {
+            gl.glPushName(serial);
+            gl.glBegin(GL.GL_TRIANGLES);
+            glVertices(gl, m);
+            gl.glEnd();
+            gl.glPopName();
+        }
+
+        /** issue gl.glVertex() for each of the triangle's points */
+        public void glVertices(GL gl, Matrix m) {
+            if (!shouldBeDrawn()) return;
+            super.glVertices(gl, m);
+        }
     }
 }