git.scottworley.com Git - nt3d/blob - rmm.html

   1 <html>
   2   <head>
   3     <title>The Thing the Rostock Was Printing in Make Magazine</title>
   4     <script type="text/javascript" src="nt3d.js"></script>
   5     <script type="text/javascript">
   6       function pointy_sin(x) {
   7         // Similar to sin(x*pi) over the range [-1,1],
   8         // but with more movement towards the extremes.
   9         // https://plus.google.com/101508799331795210529/posts/Yg7LmV8BpTw
  10         return 3.7*x + (Math.log(1-.95*x)-Math.log(.95*x+1));
  11       }
  12       function rmm(params) {
  13         var tau = Math.PI*2;
  14         var path = [];
  15         // Short arc
  16         for (var i = 0; i < params.steps_along; i++) {
  17           var progress = i/params.steps_along;
  18           var x_separation =  Math.cos(progress*tau/2)*params.base_separation;
  19           var y_offset     = -Math.sin(progress*tau/4)*params.base_offset;
  20           var y_arc        =  Math.sin(progress*tau)*params.width;
  21           var z_arc        = -Math.cos(progress*tau)*params.short_arc_height + params.short_arc_height;
  22           path.push([x_separation, y_offset + y_arc, z_arc]);
  23         }
  24         // Tall arc
  25         for (var i = 0; i < params.steps_along; i++) {
  26           var progress = i/params.steps_along;
  27           var x_arc        = -Math.cos(progress*tau*1.5)*params.base_separation;
  28           var y_offset     = -Math.cos(progress*tau/4)*params.base_offset;
  29           var y_twist      = -pointy_sin(progress*2 - 1)*params.width/2;
  30           var z_arc        = -Math.cos(progress*tau)*params.tall_arc_height + params.tall_arc_height;
  31           path.push([x_arc, y_offset + y_twist, z_arc]);
  32         }
  33         return nt3d.closed_extrude(
  34           path,
  35           nt3d.circle(params.tube_width, params.steps_around),
  36           nt3d.shapenormals_from_closed_path(path),
  37           nt3d.pathnormals_from_point(path, [0,0,0]));
  38       }
  39       var params = [["base_separation", 30],
  40                     ["base_offset", 10],
  41                     ["width", 40],
  42                     ["short_arc_height", 60],
  43                     ["tall_arc_height", 80],
  44                     ["tube_width", 10],
  45                     ["steps_along", 70, "Steps Along Each Arc"],
  46                     ["steps_around", 12]];
  47     </script>
  48   </head>
  49   <body onload="nt3d.framework(rmm, params)">
  50     <h1>The Thing the Rostock Was Printing in Make Magazine</h1>
  51     <p><a href="http://www.flickr.com/photos/jcrocholl/8065968929/sizes/l/in/photostream/">This thing</a>.</p>
  52 <!-- My notes after staring at it:
  53 x       y       z
  54 1       0       0       Bottom front
  55 .5      1       .5s     1/4 up short arc
  56 0       0       s       Top of short arc
  57 -.5     -1      .5s     Coming down short arc
  58 -1      0       0       Bottom back
  59 1       .33     .5t     1/4 up long arc
  60 0       0       t       Top of tall arc
  61 -1      -.33    .5t     Coming down tall arc
  62 1       0       0       Bottom front (Repeated from above)
  63
  64 x =  cos over 1/2 period for short arc, -cos  over 1.5 periods for tall arc
  65 y =  sin over  1  period for short arc, sin/3 over 1 period for tall arc
  66 z = -cos over  1  period for short arc, -cos  over 1 period for tall arc
  67 -->
  68   </body>
  69 </html>
  70