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

   1 <html>
   2   <head>
   3     <title>Wrap Sphere</title>
   4     <script type="text/javascript" src="nt3d.js"></script>
   5     <script type="text/javascript">
   6       function wrap_sphere(params) {
   7         // Spiral path along sphere surface
   8         var path = [];
   9         for (var i = 0; i < params.steps_along; i++) {
  10           var progress_0to2 = i / (params.steps_along/2);
  11           var progress_0to1andback = progress_0to2 < 1 ? progress_0to2 : 2 - progress_0to2;
  12           var progress_neg1to1andback = progress_0to1andback * 2 - 1;
  13           var z = progress_neg1to1andback * params.sphere_radius;
  14           var r = Math.sqrt(params.sphere_radius*params.sphere_radius - z*z);
  15           var phase_adjust = progress_0to2 < 1 ? 0 : Math.PI;
  16           var x = r*Math.cos(progress_0to1andback*params.turns*2*Math.PI + phase_adjust);
  17           var y = r*Math.sin(progress_0to1andback*params.turns*2*Math.PI + phase_adjust);
  18           path.push([x,y,z]);
  19         }
  20
  21         // Shape to be extruded
  22         var shape = nt3d.circle(params.extrusion_radius, params.steps_around);
  23         shape = nt3d.rotate_about_origin(shape, [0,0,1], params.circle_angle*Math.PI*2);
  24         for (var i = 0; i < shape.length; i++) {
  25           shape[i][0] *= params.aspect_ratio;
  26         }
  27         shape = nt3d.rotate_about_origin(shape, [0,0,1], params.distortion_angle*Math.PI*2);
  28
  29         return nt3d.closed_extrude(
  30           path,
  31           shape,
  32           nt3d.shapenormals_from_closed_path(path),
  33           nt3d.pathnormals_from_point(path, [0, 0, 0]));
  34       }
  35       var params = [["sphere_radius", 100],
  36                     ["extrusion_radius", 5],
  37                     ["turns", 3],
  38                     ["circle_angle", .125, "Angle of circle (in turns) (useful when steps_around is small)"],
  39                     ["aspect_ratio", 2],
  40                     ["distortion_angle", .25, "Distortion Angle (in turns)"],
  41                     ["steps_around", 4],
  42                     ["steps_along", 500]];
  43     </script>
  44   </head>
  45   <body onload="nt3d.framework(wrap_sphere, params)">
  46     <h1>Wrap Sphere</h1>
  47     <p>Extrude something in a spiral along the surface of a sphere.</p>
  48   </body>
  49 </html>