From 35b9db0def4913851f7515f2525cffb01a940578 Mon Sep 17 00:00:00 2001
From: adam <adam@megacz.com>
Date: Tue, 4 Dec 2007 22:29:54 -0800
Subject: [PATCH] checkpoint

darcs-hash:20071205062954-5007d-0b652b5a26bee0079d1e50429a5ee9c447707e44.gz
---
 src/edu/berkeley/qfat/Mesh.java        |   11 +++++++++++
 src/edu/berkeley/qfat/geom/Matrix.java |   22 +++++++++++++++++++++-
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/src/edu/berkeley/qfat/Mesh.java b/src/edu/berkeley/qfat/Mesh.java
index 94b4e73..08d89e7 100644
--- a/src/edu/berkeley/qfat/Mesh.java
+++ b/src/edu/berkeley/qfat/Mesh.java
@@ -135,6 +135,17 @@ public class Mesh implements Iterable<Mesh.T> {
         float oldscore = 0;
         boolean inserted = false;
 
+        public Matrix quadric() {
+            Matrix m = new Matrix(0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0);
+            E e = this.e;
+            do {
+                T t = e.t;
+                m = m.plus(t.norm().fundamentalQuadric(t.centroid()));
+                e = e.pair.next;
+            } while(e != this.e);
+            return m;
+        }
+
         public Point getPoint() { return p; }
         private Vert(Point p) {
             this.p = p;
diff --git a/src/edu/berkeley/qfat/geom/Matrix.java b/src/edu/berkeley/qfat/geom/Matrix.java
index f617376..1f25ddc 100644
--- a/src/edu/berkeley/qfat/geom/Matrix.java
+++ b/src/edu/berkeley/qfat/geom/Matrix.java
@@ -6,7 +6,7 @@ public class Matrix {
     //  [ a b c d ]   [ x ]
     //  [ e f g h ]   [ y ]
     //  [ i j k l ]   [ z ]
-    //  [ 0 0 0 1 ]   [ 1 ]
+    //  [ m n o p ]   [ 1 ]
     //
     public final float a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p;
     public Matrix() { this(1); }
@@ -36,9 +36,23 @@ public class Matrix {
         this.a = a; this.b = b; this.c = c; this.d = d; this.e = e; this.f = f; this.g = g; this.h = h; this.i = i;
         this.j = j; this.k = k; this.l = l; this.m = m; this.n = n; this.o = o; this.p = p;
     }
+    public Matrix plus(Matrix x) {
+        return new Matrix(a+x.a, b+x.b, c+x.c, d+x.d, e+x.e, f+x.f, g+x.g, h+x.h, i+x.i, j+x.j, k+x.k, l+x.l, m+x.m, n+x.n, o+x.o, p+x.p);
+    }
     public Matrix times(float x) {
         return new Matrix(a*x, b*x, c*x, d*x, e*x, f*x, g*x, h*x, i*x, j*x, k*x, l*x, m*x, n*x, o*x, p*x);
     }
+
+    /** computes (v^T)(this)(v) */
+    public float preAndPostMultiply(Point point) {
+        float ret =
+            ((a*point.x + b*point.y + c*point.z + d) * point.x) +
+            ((e*point.x + f*point.y + g*point.z + h) * point.y) +
+            ((i*point.x + j*point.y + k*point.z + l) * point.z) + 
+            ((m*point.x + n*point.y + o*point.z + p) * 1);
+        return ret;
+    }
+
     public Matrix(Vec axis, float angle) {
         double q = Math.cos(angle);
         double s = Math.sin(angle);
@@ -68,6 +82,12 @@ public class Matrix {
                          e*p.x + f*p.y + g*p.z + h,
                          i*p.x + j*p.y + k*p.z + l);
     }
+    public Vec times(Vec p) {
+        // discards bottom row
+        return new Vec(a*p.x + b*p.y + c*p.z + d,
+                       e*p.x + f*p.y + g*p.z + h,
+                       i*p.x + j*p.y + k*p.z + l);
+    }
     public Point apply(Point p) { return p; }
     public Vec apply(Vec v) { return v; }
     public Matrix invert() { return this; }
-- 
1.7.10.4