X-Git-Url: http://git.scottworley.com/nt3d/blobdiff_plain/08c25ec8473e43e82a1291a528f8332239581483..efae2dc27628eb1c0d116b24418fc48cf48c14a3:/nt3d.js

diff --git a/nt3d.js b/nt3d.js
index 9b09b09..2876698 100644
--- a/nt3d.js
+++ b/nt3d.js
@@ -62,6 +62,56 @@ 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;
+			var next = (i == path.length-1) ? 0 : i+1;
+			return nt3d.sub(path[next], path[prev]);
+		};
+	},
+	shapenormals_from_path_and_extra_points: function(path, first_point, last_point) {
+		return function(i) {
+			var prev = (i == 0) ? first_point : path[i-1];
+			var next = (i == path.length-1) ? last_point : path[i+1];
+			return nt3d.sub(next, prev);
+		};
+	},
+	shapenormals_from_path_and_first_and_last_normals: function(path, first_normal, last_normal) {
+		return function(i) {
+			if (i == 0) { return first_normal; }
+			if (i == path.length-1) { return last_normal; }
+			return nt3d.sub(path[i+1], path[i-1]);
+		};
+	},
+	pathnormals_from_point: function(path, p) {
+		// Use this with any point that is not on any path tangent line
+		var pathnormals = [];
+		for (var i = 0; i < path.length; i++) {
+			pathnormals.push(this.sub(path[i], p));
+		}
+		return pathnormals;
+	},
 	to_function: function(thing, make_indexer) {
 		// If thing is a point, just yield thing every time.
 		// If thing is a list of points && make_indexer, index into thing.
@@ -77,19 +127,19 @@ nt3d = {
 	},
 	extrude: function(path, shape, shapenormals, pathnormals) {
 
-		var guts_result = nt3d._extrude_guts(path, shape, shapenormals, pathnormals);
+		var guts_result = this._extrude_guts(path, shape, shapenormals, pathnormals);
 		// Add the end-caps
 		// XXX: This doesn't work if shape is not convex
 		return guts_result.points.concat(
-			nt3d.trianglefan(guts_result.first_loop.reverse()),
-			nt3d.trianglefan(guts_result.last_loop));
+			this.trianglefan(guts_result.first_loop.reverse()),
+			this.trianglefan(guts_result.last_loop));
 
 	},
 	closed_extrude: function(path, shape, shapenormals, pathnormals) {
-		var guts_result = nt3d._extrude_guts(path, shape, shapenormals, pathnormals);
+		var guts_result = this._extrude_guts(path, shape, shapenormals, pathnormals);
 		// Stitch the ends together
 		return guts_result.points.concat(
-			nt3d.closed_quadstrip(nt3d.zip(guts_result.first_loop, guts_result.last_loop)));
+			this.closed_quadstrip(this.zip(guts_result.first_loop, guts_result.last_loop)));
 	},
 	_extrude_guts: function(path, shape, shapenormals, pathnormals) {
 		var shape_fun = this.to_function(shape, false);
@@ -143,7 +193,7 @@ nt3d = {
 			if (i == 0) {
 				result.first_loop = loop;
 			} else {
-				result.points = result.points.concat(nt3d.closed_quadstrip(nt3d.zip(loop, prev_loop)));
+				result.points = result.points.concat(this.closed_quadstrip(this.zip(loop, prev_loop)));
 			}
 			prev_loop = loop;
 		}
@@ -190,7 +240,7 @@ nt3d = {
 	},
 	project: function(a, b) { // Project b onto a
 		var a_magnitude = this.magnitude(a);
-		return this.scale(a, this.dot(a, b) / a_magnitude * a_magnitude);
+		return this.scale(a, this.dot(a, b) / (a_magnitude * a_magnitude));
 	},
 	project_to_orthogonal: function(a, b) {
 		// The nearest thing to b that is orthogonal to a
@@ -199,12 +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));
 	},