From 1eac51e2609309292283f0c0395df35b925b4fd4 Mon Sep 17 00:00:00 2001
From: Joost Nieuwenhuijse <joost@newhouse.nl>
Date: Sat, 21 Jan 2012 18:56:46 +0100
Subject: [PATCH] Added mirroring of solids

---
 csg.js     | 37 ++++++++++++++++++++++++++++++++++++-
 index.html | 18 ++++++++++++++++--
 2 files changed, 52 insertions(+), 3 deletions(-)

diff --git a/csg.js b/csg.js
index 01fc9fa..bf44224 100644
--- a/csg.js
+++ b/csg.js
@@ -203,7 +203,7 @@ CSG.prototype = {
   // Return a new CSG solid with solid and empty space switched. This solid is
   // not modified.
   inverse: function() {
-    var flippedpolygons = this.polygons.map(function(p) { p.flipped(); });
+    var flippedpolygons = this.polygons.map(function(p) { return p.flipped(); });
     return CSG.fromPolygons(flippedpolygons);
   },
   
@@ -212,6 +212,26 @@ CSG.prototype = {
     var newpolygons = this.polygons.map(function(p) { return p.transform(matrix4x4); } );
     return CSG.fromPolygons(newpolygons);  
   },
+
+  mirrored: function(plane) {
+    var newpolygons = this.polygons.map(function(p) { return p.mirrored(plane); } );
+    return CSG.fromPolygons(newpolygons);  
+  },
+  
+  mirroredX: function() {
+    var plane = new CSG.Plane(new CSG.Vector3D(1,0,0), 0);
+    return this.mirrored(plane);
+  },
+  
+  mirroredY: function() {
+    var plane = new CSG.Plane(new CSG.Vector3D(0,1,0), 0);
+    return this.mirrored(plane);
+  },
+  
+  mirroredZ: function() {
+    var plane = new CSG.Plane(new CSG.Vector3D(0,0,1), 0);
+    return this.mirrored(plane);
+  },
   
   translate: function(v) {
     return this.transform(CSG.Matrix4x4.translation(v));
@@ -1130,6 +1150,12 @@ CSG.Plane.prototype = {
   toString: function() {
     return "[normal: "+this.normal.toString()+", w: "+this.w+"]";
   },
+  
+  mirrorPoint: function(point3d) {
+    var distance = this.signedDistanceToPoint(point3d);
+    var mirrored = point3d.minus(this.normal.times(distance * 2.0));
+    return mirrored;
+  },
 };
 
 
@@ -1290,6 +1316,15 @@ CSG.Polygon.prototype = {
     return new CSG.Polygon(newvertices, this.shared, newplane);
   },
   
+  mirrored: function(plane) {
+    var newvertices = this.vertices.map(function(v) {
+      var newpos = plane.mirrorPoint(v.pos);
+      return new CSG.Vertex(newpos);
+    });
+    newvertices.reverse();
+    return new CSG.Polygon(newvertices, this.shared);
+  },
+  
   // Affine transformation of polygon. Returns a new CSG.Polygon
   transform: function(matrix4x4) {
     var newvertices = this.vertices.map(function(v) { return v.transform(matrix4x4); } );
diff --git a/index.html b/index.html
index 91f969a..f0cca01 100644
--- a/index.html
+++ b/index.html
@@ -226,7 +226,6 @@ var cube = CSG.roundedCube({
 <h2>CSG operations</h2>
 The 3 standard CSG operations are supported. All CSG operations return a new solid; the source solids
 are not modified:
-<br><br> 
 <pre>
 var csg1 = cube.union(sphere);
 var csg2 = cube.intersect(sphere);
@@ -235,7 +234,6 @@ var csg3 = cube.subtract(sphere);
 
 <h2>Transformations</h2>
 Solids can be translated, scaled and rotated. Multiple transforms can be combined into a single matrix transform:
-<br><br> 
 <pre>
 var cube = CSG.cube();
 
@@ -262,6 +260,22 @@ m = m.multiply(CSG.Matrix4x4.scaling([1.1, 1.2, 1.3]));
 var cube3 = cube.transform(m);
 </pre>
 
+<h2>Mirroring</h2>
+Solids can be mirrored in any plane in 3D space:
+<pre>
+var cube = CSG.cube().translate([1,0,0]);
+
+var cube2 = cube.mirroredX(); // mirrored in the x=0 plane
+var cube3 = cube.mirroredY(); // mirrored in the y=0 plane
+var cube4 = cube.mirroredZ(); // mirrored in the z=0 plane
+
+// create a plane by specifying 3 points:
+var plane = CSG.Plane.fromPoints([5,0,0], [5, 1, 0], [3, 1, 7]);
+
+// and mirror in that plane:
+var cube5 = cube.mirrored(plane);
+</pre>
+
 <h2>Expansion and contraction</h2>
 Expansion can be seen
 as the 3D convolution of an object with a sphere. Contraction is the reverse: the area outside the solid