X-Git-Url: http://git.scottworley.com/nt3d/blobdiff_plain/7731ed7a4c4845e60f937dd1f082b1ce24939607..efae2dc27628eb1c0d116b24418fc48cf48c14a3:/nt3d.js

diff --git a/nt3d.js b/nt3d.js
index 62d898e..2876698 100644
--- a/nt3d.js
+++ b/nt3d.js
@@ -62,6 +62,27 @@ nt3d = {
 		return this.closed_trianglefan([apex].concat(base)).concat(
 		       this.trianglefan(base.reverse()));
 	},
+	sphere: function(center, radius, latitude_steps, longitude_steps) {
+		return this.oriented_sphere(center, radius, [0,0,1], [1,0,0], latitude_steps, longitude_steps);
+	},
+	oriented_sphere: function(center, radius, north, greenwich, latitude_steps, longitude_steps) {
+		var unit_north = this.unit(north);
+		var north_pole = this.translate_point(this.scale(unit_north,  radius), center);
+		var south_pole = this.translate_point(this.scale(unit_north, -radius), center);
+		return this.spheroid(north_pole, south_pole, radius, greenwich, latitude_steps, longitude_steps);
+	},
+	spheroid: function(north_pole, south_pole, radius, greenwich, latitude_steps, longitude_steps) {
+		var delta = this.sub(north_pole, south_pole);
+		var path = [];
+		for (var i = 0; i < latitude_steps-1; i++) {
+			path.push(this.translate_point(south_pole, this.scale(delta, (1-Math.cos(Math.PI*i/(latitude_steps-1)))/2)));
+		}
+		path.push(north_pole);
+		function shape(i) {
+			return nt3d.circle(radius*Math.sin(Math.PI*i/(latitude_steps-1)), longitude_steps);
+		}
+		return this.extrude(path, shape, delta, greenwich);
+	},
 	shapenormals_from_closed_path: function(path) {
 		return function(i) {
 			var prev = (i == 0) ? path.length-1 : i-1;
@@ -228,12 +249,15 @@ nt3d = {
 	translate: function(points, offset) {
 		var translated = [];
 		for (var i = 0; i < points.length; i++) {
-			translated[i] = [points[i][0] + offset[0],
-			                 points[i][1] + offset[1],
-			                 points[i][2] + offset[2]];
+			translated[i] = this.translate_point(points[i], offset);
 		}
 		return translated;
 	},
+	translate_point: function(point, offset) {
+		return [point[0] + offset[0],
+		        point[1] + offset[1],
+		        point[2] + offset[2]];
+	},
 	angle_between: function(a, b) { // a and b must be unit vectors
 		return Math.acos(this.dot(a, b));
 	},