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(base_separation, base_offset,
  13                    width, short_arc_height, tall_arc_height,
  14                    tube_width, steps_along, steps_around) {
  15         var tau = Math.PI*2;
  16         var path = [];
  17         // Short arc
  18         for (var i = 0; i < steps_along; i++) {
  19           var progress = i/steps_along;
  20           var x_separation =  Math.cos(progress*tau/2)*base_separation;
  21           var y_offset     = -Math.sin(progress*tau/4)*base_offset;
  22           var y_arc        =  Math.sin(progress*tau)*width;
  23           var z_arc        = -Math.cos(progress*tau)*short_arc_height + short_arc_height;
  24           path.push([x_separation, y_offset + y_arc, z_arc]);
  25         }
  26         // Tall arc
  27         for (var i = 0; i < steps_along; i++) {
  28           var progress = i/steps_along;
  29           var x_arc        = -Math.cos(progress*tau*1.5)*base_separation;
  30           var y_offset     = -Math.cos(progress*tau/4)*base_offset;
  31           var y_twist      = -pointy_sin(progress*2 - 1)*width/2;
  32           var z_arc        = -Math.cos(progress*tau)*tall_arc_height + tall_arc_height;
  33           path.push([x_arc, y_offset + y_twist, z_arc]);
  34         }
  35         return nt3d.closed_extrude(
  36           path,
  37           nt3d.circle(tube_width, steps_around),
  38           nt3d.shapenormals_from_closed_path(path),
  39           nt3d.pathnormals_from_point(path, [0,0,0]));
  40       }
  41       var params = [["Base separation", 30],
  42                     ["Base offset", 10],
  43                     ["Width", 40],
  44                     ["Short arc height", 60],
  45                     ["Tall arc height", 80],
  46                     ["Tube width", 10],
  47                     ["Steps along each arc", 70],
  48                     ["Steps around", 12]];
  49     </script>
  50   </head>
  51   <body onload="nt3d.framework(rmm, params)">
  52     <h1>The Thing the Rostock Was Printing in Make Magazine</h1>
  53     <p><a href="http://www.flickr.com/photos/jcrocholl/8065968929/sizes/l/in/photostream/">This thing</a>.</p>
  54 <!-- My notes after staring at it:
  55 x       y       z
  56 1       0       0       Bottom front
  57 .5      1       .5s     1/4 up short arc
  58 0       0       s       Top of short arc
  59 -.5     -1      .5s     Coming down short arc
  60 -1      0       0       Bottom back
  61 1       .33     .5t     1/4 up long arc
  62 0       0       t       Top of tall arc
  63 -1      -.33    .5t     Coming down tall arc
  64 1       0       0       Bottom front (Repeated from above)
  65
  66 x =  cos over 1/2 period for short arc, -cos  over 1.5 periods for tall arc
  67 y =  sin over  1  period for short arc, sin/3 over 1 period for tall arc
  68 z = -cos over  1  period for short arc, -cos  over 1 period for tall arc
  69 -->
  70   </body>
  71 </html>
  72