From b987cd997410c14c4ce5076d3aa39c7903b62b2f Mon Sep 17 00:00:00 2001
From: adam <adam@megacz.com>
Date: Sun, 25 Nov 2007 21:21:13 -0800
Subject: [PATCH] sanity checks

darcs-hash:20071126052113-5007d-aaa2ac52cf17a0bba63d8f4907750b9344920554.gz
---
 src/Geom.java |   29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/src/Geom.java b/src/Geom.java
index 38e41f2..a30b9a7 100644
--- a/src/Geom.java
+++ b/src/Geom.java
@@ -35,7 +35,6 @@ public class Geom implements Iterable<Geom.T> {
         P p1 = e1.shared(e2);
         P p2 = e2.shared(e3);
         P p3 = e3.shared(e1);
-        // FEATURE: colinearity check?
         V norm2 = p2.minus(p1).cross(p3.minus(p1));
         float dot = norm.dot(norm2);
         if (Math.abs(dot) < EPSILON) throw new Error("dot products within epsilon of each other: "+norm+" "+norm2);
@@ -100,7 +99,11 @@ public class Geom implements Iterable<Geom.T> {
     public final class E {
         public final P p1, p2;
         T t1, t2;
-        public E(P p1, P p2) { this.p1 = p1; this.p2 = p2; }
+        public E(P p1, P p2) {
+            if (p1==p2) throw new Error("attempt to create edge with single vertex: " + p1);
+            this.p1 = p1;
+            this.p2 = p2;
+        }
         public int hashCode() { return p1.hashCode() ^ p2.hashCode(); }
         public float length() { return p1.minus(p2).mag(); }
         public boolean equals(Object o) {
@@ -139,12 +142,6 @@ public class Geom implements Iterable<Geom.T> {
     /** [UNIQUE] a triangle (face) */
     public final class T {
         public final E e1, e2, e3;
-        public V norm() {
-            P p1 = e1.shared(e2);
-            P p2 = e2.shared(e3);
-            P p3 = e3.shared(e1);
-            return p2.minus(p1).cross(p3.minus(p1)).norm();
-        }
         T(E e1, E e2, E e3) {
             if (e1.p1.t==null) e1.p1.t = this;
             if (e1.p2.t==null) e1.p2.t = this;
@@ -152,12 +149,28 @@ public class Geom implements Iterable<Geom.T> {
             if (e2.p2.t==null) e2.p2.t = this;
             if (e3.p1.t==null) e3.p1.t = this;
             if (e3.p2.t==null) e3.p2.t = this;
+            if (e1==e2) throw new Error("attempt to create triangle with duplicate edge: " + e1);
+            if (e2==e3) throw new Error("attempt to create triangle with duplicate edge: " + e2);
+            if (e3==e1) throw new Error("attempt to create triangle with duplicate edge: " + e3);
+            // check that each pair of edges shares a vertex
+            e1.shared(e2);
+            e2.shared(e3);
+            e3.shared(e1);
             this.e1 = e1;
             this.e2 = e2;
             this.e3 = e3;
+            // FEATURE: colinearity/sliverness check?
             if (e1.t1 == null) e1.t1 = this; else if (e1.t2 == null) e1.t2 = this; else throw new Error("non-manifold surface");
             if (e2.t1 == null) e2.t1 = this; else if (e2.t2 == null) e2.t2 = this; else throw new Error("non-manifold surface");
             if (e3.t1 == null) e3.t1 = this; else if (e3.t2 == null) e3.t2 = this; else throw new Error("non-manifold surface");
+            // FIXME: check that triangles we share an edge with agree on the direction of the normal vector
+            // FIXME: check for sealed/watertight surface once construction is complete (an infer normal(s)?)
+        }
+        public V norm() {
+            P p1 = e1.shared(e2);
+            P p2 = e2.shared(e3);
+            P p3 = e3.shared(e1);
+            return p2.minus(p1).cross(p3.minus(p1)).norm();
         }
         public boolean hasE(E e) { return e1==e || e2==e || e3==e; }
         public void glVertices(GL gl) {
-- 
1.7.10.4