un broke some things

js/mobius.js

@@ -77,11 +77,6 @@ function add_2d_ctrl(parent,variable,label,min_x,max_x,min_y,max_y) {
 }
 
 function add_vector_field(){
-    var canvas = document.createElement('canvas');
-    canvas.style.border   = "1px solid";
-    canvas.id = 'canvas'
-    canvas.height = 500;
-    canvas.width = 500;
     ctx = canvas.getContext('2d');
 
     height = canvas.height;
@@ -91,8 +86,7 @@ function add_vector_field(){
 
 //update based on id
 function update_vector_field(a,b,c,d){
-    canvas = document.getElementById('canvas')
-    ctx = canvas.getContext('2d')
+    ctx = canvas.getContext('2d');
 
     ctx.moveTo(0,0);
     ctx.clearRect(0,0,600,600)
@@ -303,7 +297,12 @@ $(function () {//document is ready, setup everything
     add_2d_ctrl($(guibox),c,"c",-1,1,-1,1);
     add_2d_ctrl($(guibox),d,"d",-1,1,-1,1);
 
-
+    canvas = document.createElement('canvas');
+    canvas.style.border   = "1px solid";
+    canvas.id = 'canvas'
+    canvas.height = 500;
+    canvas.width = 500;
+    document.body.appendChild(canvas);
 
     glCanvas = document.createElement("canvas");
     glCanvas.id = 'glcanvas';