From 2013f9f4667d81ae60a5834501cc4a82d17b8e10 Mon Sep 17 00:00:00 2001
From: Jonathan Westhues <jwesthues@cq.cx>
Date: Wed, 10 Jun 2009 00:04:35 -0800
Subject: [PATCH] Oops, was computing numerical by perturbing a point in uv;
 but the xyz point that I subtracted off had been refined to lie exactly on
 our edge's curve, and the uv point that I started with had not. So normals
 got randomly screwed up.

[git-p4: depot-paths = "//depot/solvespace/": change = 1978]
---
 solvespace.cpp  | 2 +-
 srf/boolean.cpp | 5 +++--
 util.cpp        | 7 +++++--
 3 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/solvespace.cpp b/solvespace.cpp
index 43ff666..1ace0e8 100644
--- a/solvespace.cpp
+++ b/solvespace.cpp
@@ -57,7 +57,7 @@ void SolveSpace::Init(char *cmdLine) {
     lightDir[1].y = CnfThawFloat( 0.0f, "LightDir_1_Up"        );
     lightDir[1].z = CnfThawFloat( 0.0f, "LightDir_1_Forward"   );
     // Chord tolerance
-    chordTol = CnfThawFloat(1.5f, "ChordTolerance");
+    chordTol = CnfThawFloat(2.0f, "ChordTolerance");
     // Max pwl segments to generate
     maxSegments = CnfThawDWORD(10, "MaxSegments");
     // View units
diff --git a/srf/boolean.cpp b/srf/boolean.cpp
index 30789dc..b8a368f 100644
--- a/srf/boolean.cpp
+++ b/srf/boolean.cpp
@@ -276,7 +276,6 @@ void SSurface::EdgeNormalsWithinSurface(Point2d auv, Point2d buv,
     Point2d enuv = abuv.Normal();
 
     *pt    = PointAt(muv);
-    *surfn = NormalAt(muv.x, muv.y);
 
     // If this edge just approximates a curve, then refine our midpoint so
     // so that it actually lies on that curve too. Otherwise stuff like
@@ -288,8 +287,11 @@ void SSurface::EdgeNormalsWithinSurface(Point2d auv, Point2d buv,
         double t;
         sc->exact.ClosestPointTo(*pt, &t, false);
         *pt = sc->exact.PointAt(t);
+        ClosestPointTo(*pt, &muv);
     }
 
+    *surfn = NormalAt(muv.x, muv.y);
+
     // Compute the inner and outer normals of this edge (within the srf),
     // in xyz space. These are not necessarily antiparallel, if the
     // surface is curved.
@@ -487,7 +489,6 @@ void SShell::MakeIntersectionCurvesAgainst(SShell *agnst, SShell *into) {
             // list for into.
             sa->IntersectAgainst(sb, this, agnst, into);
         }
-        FLAG++;
     }
 }
 
diff --git a/util.cpp b/util.cpp
index 0b58aed..e2a8006 100644
--- a/util.cpp
+++ b/util.cpp
@@ -510,8 +510,11 @@ Vector Vector::ScaledBy(double v) {
 Vector Vector::WithMagnitude(double v) {
     double m = Magnitude();
     if(m == 0) {
-        dbp("Vector::WithMagnitude of zero vector!");
-        return From(v, 0, 0);
+        // We can do a zero vector with zero magnitude, but not any other cases.
+        if(fabs(v) > 1e-100) {
+            dbp("Vector::WithMagnitude of zero vector!");
+        }
+        return From(0, 0, 0);
     } else {
         return ScaledBy(v/m);
     }