adding README.md, not that it helps

Author: mikolalysenko

README.md

@@ -1,4 +1,82 @@
 ndarray-extract-contour
 =======================
+General purpose contour extraction routine generator.  This library has a really horrible interface, but it is pretty flexible.  It is mostly useful as an internal component, and should not be used generally unless you know what you are doing.
 
-**WORK IN PROGRESS, CHECK BACK LATER**
+As an example of a nicer interface built using this module, take a look at [surface-nets](https://github.com/mikolalysenko/surface-nets).
+
+# Example/documentation
+
+```javascript
+var generateContour = require("ndarray-extract-contour")
+
+var getContour = generateContour({
+  order: [1,0],         //Order of array iteration
+  arrayArguments: 2,    //Take two arrays as input
+  scalarArguments: 1,   //Take one extra scalar argument
+
+  //Function to determine phase of a grid cell
+  phase: function(a, b, s) { 
+
+    //a = first array argument
+    //b = second array argument
+    //s = scalar argument
+
+    return a
+  },
+
+  //Callback for adding vertex to array
+  vertex: function(x,y, a00,a01,a10,a11,  b00,b01,b10,b11,  p00,p01,p10,p11, s) {
+
+    //Geometry:
+    //
+    //   a11 ---- a10
+    //    |        |
+    //    |        |
+    //    |        |
+    //   a01 ---- a00
+    //
+
+    //Arguments:
+
+    // x,y,...  = coordinates of vertex in grid index
+    // a00,a01,...  = components of first array
+    // b00,b01,...  = components of second array
+    // p00,p01,...  = phase of all nearby cells
+    // s,... = optional scalar arguments
+    //
+  },
+
+  //Callback for adding cell
+  cell: function(v0,v1,  a0,a1,  b0,b1,  p0,p1,  s) {
+
+    // Geometry:
+    //
+    //       v0
+    //       |
+    //  p0   |    p1
+    //       |
+    //       v1
+
+
+    //Arguments:
+    //  v0,v1,...  = coordinates of vertices of cuboid cell
+    //  a0,a1  = first array values on front/back cell
+    //  b0,b1  = second array values on front/back cell
+    //  p0,p1  = phase values for front/back cell
+    //  s,... = optional scalar arguments
+  }
+})
+
+
+//How to use it:
+testContour(A, B, S)
+```
+
+# Install
+
+```
+npm install ndarray-extract-contour
+```
+
+# Credits
+(c) 2014 Mikola Lysenko. MIT License

contour.js

@@ -1,11 +1,6 @@
 "use strict"
 
-//DEBUG
-var beautify = require("js-beautify")
-
 var pool = require("typedarray-pool")
-var gray = require("gray-code")
-var invert = require("invert-permutation")
 
 module.exports = createSurfaceExtractor
 
@@ -62,21 +57,6 @@ var POOL_SIZE = "Q"
 var POINTER = "X"
 var TEMPORARY = "T"
 
-function fixPerm(face, dimension, k) {
-  var seq = gray(dimension-1).map(function(f) {
-    return f.reduce(function(p, x, i) {
-      return p + (x << i)
-    }, 0)
-  })
-  var x = seq.map(function(y) {
-    return face[y]
-  })
-  if(k & 1) {
-    x.reverse()
-  }
-  return x
-}
-
 function permBitmask(dimension, mask, order) {
   var r = 0
   for(var i=0; i<dimension; ++i) {
@@ -91,7 +71,6 @@ function permBitmask(dimension, mask, order) {
 function compileSurfaceProcedure(vertexFunc, faceFunc, phaseFunc, scalarArgs, order, typesig) {
   var arrayArgs = typesig.length
   var dimension = order.length
-  var invOrder = invert(order)
 
   if(dimension < 2) {
     throw new Error("ndarray-extract-contour: Dimension must be at least 2")
@@ -141,8 +120,8 @@ function compileSurfaceProcedure(vertexFunc, faceFunc, phaseFunc, scalarArgs, or
   for(var i=0; i<arrayArgs; ++i) {
     for(var j=0; j<dimension; ++j) {
       var stepVal = [ stride(i,order[j]) ]
-      for(var k=j-1; k>=0; --k) {
-        stepVal.push(stride(i, order[k]) + "*" + shape(order[k]) )
+      if(j > 0) {
+        stepVal.push(stride(i, order[j-1]) + "*" + shape(order[j-1]) )
       }
       vars.push(step(i,order[j]) + "=(" + stepVal.join("-") + ")|0")
     }
@@ -217,8 +196,6 @@ function compileSurfaceProcedure(vertexFunc, faceFunc, phaseFunc, scalarArgs, or
     for(var i=0; i<scalarArgs; ++i) {
       phaseFuncArgs.push(scalar(i))
     }
-    //code.push("console.log('o',p0,X,e1,e2,e3);")
-    
     code.push(PHASES, "[", POINTER, "++]=phase(", phaseFuncArgs.join(), ");")
     for(var i=0; i<k; ++i) {
       forLoopEnd(i)
@@ -246,7 +223,6 @@ function compileSurfaceProcedure(vertexFunc, faceFunc, phaseFunc, scalarArgs, or
     for(var i=0; i<scalarArgs; ++i) {
       phaseFuncArgs.push(scalar(i))
     }
-    //code.push("console.log(p0,X,e1,e2,e3);")
 
     code.push(pcube(0), "=", PHASES, "[", POINTER, "]=phase(", phaseFuncArgs.join(), ");")
 
@@ -286,7 +262,6 @@ function compileSurfaceProcedure(vertexFunc, faceFunc, phaseFunc, scalarArgs, or
     }
 
     //Generate vertex
-    code.push("console.log('callv:',i0,i1,N,X,p0,e1,e2,e3,d0_1,d0_2,d0_3);")
     code.push("vertex(", vertexArgs.join(), ");",
       vert(0), "=", VERTEX_IDS, "[", POINTER, "]=", VERTEX_COUNT, "++;")
 
@@ -303,16 +278,22 @@ function compileSurfaceProcedure(vertexFunc, faceFunc, phaseFunc, scalarArgs, or
           faceArgs.push(VERTEX_IDS + "[" + POINTER + "+" + pdelta(k) + "]")
         }
         faceArgs.push(vert(0))
-        faceArgs = fixPerm(faceArgs, dimension, j)
         for(var k=0; k<arrayArgs; ++k) {
-          faceArgs.push(cube(k,base), cube(k,subset))
+          if(j&1) {
+            faceArgs.push(cube(k,base), cube(k,subset))
+          } else {
+            faceArgs.push(cube(k,subset), cube(k,base))
+          }
+        }
+        if(j&1) {
+          faceArgs.push(corner, edge)
+        } else {
+          faceArgs.push(edge, corner)
         }
-        faceArgs.push(corner, edge)
         for(var k=0; k<scalarArgs; ++k) {
           faceArgs.push(scalar(k))
         }
         code.push("if(", corner, "!==", edge, "){",
-          "console.log('face', i0,i1, ",j,",",mask,");",
           "face(", faceArgs.join(), ")}")
       }
     }
@@ -372,9 +353,6 @@ function compileSurfaceProcedure(vertexFunc, faceFunc, phaseFunc, scalarArgs, or
     "}",
     "return ", funcName ].join("")
 
-  //Print code
-  console.log(beautify(procedureCode))
-
   var proc = new Function(
     "vertex", 
     "face", 

test/test.js

@@ -12,19 +12,22 @@ tape("test-vectorize", function(t) {
   var testVectorizer = createExtractor({
     order: [1, 0],
     vertex: function(x, y) {
-      console.log("v:", x,y)
+      verts.push([x,y])
     },
     phase: function(s) {
-      return s < 0
+      console.log(s)
+      return s
     },
     cell: function(i, j, p0, p1) {
-      console.log("f:", i,j, p0, p1p1)
+      cells.push([i,j,p0,p1])
     }
   })
+  console.log(verts, cells)
 
   testVectorizer(pack(
-    [ [0,1,0],
-      [1,1,1,],
-      [0,1,0]]))
+    [ [0,1,0,0],
+      [0,1,1,1],
+      [1,1,1,0],
+      [0,0,1,0] ] ))
   t.end()
 })