<html> <head> <title>Wrap Sphere</title> <script type="text/javascript" src="nt3d.js"></script> <script type="text/javascript"> function wrap_sphere(sphere_radius, extrusion_radius, turns, circle_angle, aspect_ratio, distortion_angle, steps_around, steps_along) { // Spiral path along sphere surface var path = []; for (var i = 0; i < steps_along; i++) { var progress_0to2 = i / (steps_along/2); var progress_0to1andback = progress_0to2 < 1 ? progress_0to2 : 2 - progress_0to2; var progress_neg1to1andback = progress_0to1andback * 2 - 1; var z = progress_neg1to1andback * sphere_radius; var r = Math.sqrt(sphere_radius*sphere_radius - z*z); var phase_adjust = progress_0to2 < 1 ? 0 : Math.PI; var x = r*Math.cos(progress_0to1andback*turns*2*Math.PI + phase_adjust); var y = r*Math.sin(progress_0to1andback*turns*2*Math.PI + phase_adjust); path.push([x,y,z]); } // Shape to be extruded var shape = nt3d.circle(extrusion_radius, steps_around); shape = nt3d.rotate_about_origin(shape, [0,0,1], circle_angle*Math.PI*2); for (var i = 0; i < shape.length; i++) { shape[i][0] *= aspect_ratio; } shape = nt3d.rotate_about_origin(shape, [0,0,1], distortion_angle*Math.PI*2); return nt3d.closed_extrude( path, shape, nt3d.shapenormals_from_closed_path(path), nt3d.pathnormals_from_point(path, [0, 0, 0])); } var params = [["Sphere radius", 100], ["Extrusion radius", 5], ["Turns", 3], ["Angle of circle (in turns) (useful when steps_around is small)", .125], ["Aspect ratio", 2], ["Angle of distortion (in turns)", .25], ["Steps around", 4], ["Steps along", 500]]; </script> </head> <body onload="nt3d.framework(wrap_sphere, params)"> <h1>Wrap Sphere</h1> <p>Extrude something in a spiral along the surface of a sphere.</p> </body> </html>