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(sphere_radius, extrusion_radius, turns, circle_angle, aspect_ratio, distortion_angle, steps_around, steps_along) {
   7         // Spiral path along sphere surface
   8         var path = [];
   9         for (var i = 0; i < steps_along; i++) {
  10           var progress_0to2 = i / (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 * sphere_radius;
  14           var r = Math.sqrt(sphere_radius*sphere_radius - z*z);
  15           var phase_adjust = progress_0to2 < 1 ? 0 : Math.PI;
  16           var x = r*Math.cos(progress_0to1andback*turns*2*Math.PI + phase_adjust);
  17           var y = r*Math.sin(progress_0to1andback*turns*2*Math.PI + phase_adjust);
  18           path.push([x,y,z]);
  19         }
  20
  21         // Shape to be extruded
  22         var shape = nt3d.circle(extrusion_radius, steps_around);
  23         shape = nt3d.rotate_about_origin(shape, [0,0,1], circle_angle*Math.PI*2);
  24         for (var i = 0; i < shape.length; i++) {
  25           shape[i][0] *= aspect_ratio;
  26         }
  27         shape = nt3d.rotate_about_origin(shape, [0,0,1], 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                     ["Angle of circle (in turns) (useful when steps_around is small)", .125],
  39                     ["Aspect ratio", 2],
  40                     ["Angle of distortion (in turns)", .25],
  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>