X-Git-Url: http://git.scottworley.com/nt3d/blobdiff_plain/72eac64d07af484314745fd0e9466e0f94915684..34c919e9878654f7fa6e9a61ef401e150b8a5ff0:/nt3d.js

diff --git a/nt3d.js b/nt3d.js
index 0389946..80390b9 100644
--- a/nt3d.js
+++ b/nt3d.js
@@ -181,7 +181,16 @@ nt3d = {
 
 			// 2. Rotate around shapenormali so that [1,0,0]
 			//    becomes pathnormali.
-			loop = this.rotate_onto(loop, shapex, pathnormali);
+			if (!this.opposite(shapex, pathnormali)) {
+				loop = this.rotate_onto(loop, shapex, pathnormali);
+			} else {
+				// Rare edge case: When shapex and pathnormali are
+				// opposite, rotate_onto cannot cross them to get
+				// an axis of rotation.  In this case, we (extrude)
+				// already know what to do -- just rotate PI around
+				// shapenormali!
+				loop = this.rotate_about_origin(loop, shapenormali, Math.PI);
+			}
 
 			// (This would probably be faster and more numerically stable
 			// if the two rotations were applied as one combined operation
@@ -283,17 +292,40 @@ nt3d = {
 		}
 		return rotated;
 	},
+	angle_epsilon: 1e-7,
+	opposite: function(a, b) {
+		// Do a and b point in exactly opposite directions?
+		return Math.abs(this.angle_between(this.unit(a), this.unit(b)) - Math.PI) < this.angle_epsilon;
+	},
 	rotate_onto: function(points, a, b) {
 		// Rotate points such that a (in points-space) maps onto b
 		// by crossing a and b to get a rotation axis and using
 		// angle_between to get a rotation angle.
 		var angle = this.angle_between(this.unit(a), this.unit(b));
-		if (Math.abs(angle) < 1e-15) {
-			// No siginificant rotation to perform.  Bail to avoid
+		var abs_angle = Math.abs(angle);
+		if (Math.abs(angle) < this.angle_epsilon) {
+			// No significant rotation to perform.  Bail to avoid
 			// NaNs and numerical error
 			return points;
 		}
-		var axis = this.unit(this.cross(a, b));
+		var axis;
+		if (Math.abs(abs_angle - Math.PI) < this.angle_epsilon) {
+			// a and b point in opposite directions, so
+			// we cannot cross them.  So just pick something.
+			// If the caller wishes to avoid this behaviour,
+			// they should check with this.opposite() first.
+			axis = this.project_to_orthogonal(a, [1,0,0]);
+			console.log("rotate_onto: a and b are opposite!  If you carefully chose them to meet some other constraint, you will be sad!  Arbitrarily using axis [1,0,0] ->", axis);
+			if (this.magnitude(axis) < this.angle_epsilon) {
+				// Oh, double bad luck!  Our arbitrary choice
+				// lines up too!  A second, orthogonal arbitrary
+				// choice is now guaranteed to succeed.
+				axis = this.project_to_orthogonal(a, [0,1,0]);
+				console.log("rotate_onto: Double bad luck!  Arbitrarily using axis [0,1,0] ->", axis);
+			}
+		} else {
+			axis = this.unit(this.cross(a, b));
+		}
 		return this.rotate_about_origin(points, axis, angle);
 	},
 	rotate: function(points, center, axis, angle) { // axis must be a unit vector
@@ -315,41 +347,20 @@ nt3d = {
 		       this.point_equal(b, c, this.degenerate_face_epsilon) ||
 		       this.point_equal(c, a, this.degenerate_face_epsilon);
 	},
-	go: function() {
-		// Remove any previous download links
-		var old_download_link = document.getElementById("nt3d_download");
-		if (old_download_link) {
-			old_download_link.parentNode.removeChild(old_download_link);
-		}
-
-		// Continue in a callback, so that there's not a stale download
-		// link hanging around while we process.
-		setTimeout(function(the_this) { (function() {
-
-		// Get params from form
-		var params = [];
-		for (var i = 0; i < this.user_params.length; i++) {
-			var as_string = this.form.elements["param"+i].value;
-			var as_num = +as_string;
-			params[i] = isNaN(as_num) ? as_string : as_num;
-		}
-
-		// Run user_function
-		this.points = this.user_function.apply(null, params);
-
+	validate: function(points) {
 		// Do a little validation
-		if (this.points.length % 3 != 0) {
+		if (points.length % 3 != 0) {
 			alert("Points list length not divisble by 3!");
 		}
 		var nan_count = 0;
 		var nan_point_count = 0;
 		var nan_face_count = 0;
-		for (var i = 0; i < this.points.length/3; i++) {
+		for (var i = 0; i < points.length/3; i++) {
 			var nan_in_face = false;
 			for (var j = 0; j < 3; j++) {
 				var nan_in_point = false;
 				for (var k = 0; k < 3; k++) {
-					if (isNaN(this.points[i*3+j][k])) {
+					if (isNaN(points[i*3+j][k])) {
 						nan_count++;
 						nan_in_point = true;
 						nan_in_face = true;
@@ -360,16 +371,17 @@ nt3d = {
 			if (nan_in_face) nan_face_count ++;
 		}
 		if (nan_count != 0) {
-			alert(nan_count + " NaNs in " + nan_point_count + " points in " + nan_face_count + " faces (" + (100 * nan_face_count / (this.points.length/3)) + "% of faces).");
+			alert(nan_count + " NaNs in " + nan_point_count + " points in " + nan_face_count + " faces (" + (100 * nan_face_count / (points.length/3)) + "% of faces).");
 		}
-
-		// Remove degenerate faces
+	},
+	remove_degenerate_faces: function(points) {
+		// Note: This modifies points
 		var degenerate_face_count = 0;
-		for (var i = 0; i < this.points.length/3; i++) {
-			if (this.is_degenerate(this.points[i*3+0], 
-			                       this.points[i*3+1], 
-			                       this.points[i*3+2])) {
-				this.points.splice(i*3, 3);
+		for (var i = 0; i < points.length/3; i++) {
+			if (this.is_degenerate(points[i*3+0], 
+			                       points[i*3+1], 
+			                       points[i*3+2])) {
+				points.splice(i*3, 3);
 				i--;
 				degenerate_face_count ++;
 			}
@@ -377,15 +389,16 @@ nt3d = {
 		if (degenerate_face_count != 0) {
 			console.log("Removed " + degenerate_face_count + " degenerate faces");
 		}
-
-		// Make STL
-		this.stl = "solid " + this.user_function.name + "\n";
-		for (var i = 0; i < this.points.length/3; i++) {
-			var a = this.points[i*3+0];
-			var b = this.points[i*3+1];
-			var c = this.points[i*3+2];
+		return points;
+	},
+	to_stl: function(points, name) {
+		var stl = "solid " + name + "\n";
+		for (var i = 0; i < points.length/3; i++) {
+			var a = points[i*3+0];
+			var b = points[i*3+1];
+			var c = points[i*3+2];
 			var normal = this.normal(a, b, c);
-			this.stl += "facet normal " + normal[0] + " " + normal[1] + " " + normal[2] + "\n" +
+			stl += "facet normal " + normal[0] + " " + normal[1] + " " + normal[2] + "\n" +
 				"outer loop\n" +
 				"vertex " + a[0] + " " + a[1] + " " + a[2] + "\n"+
 				"vertex " + b[0] + " " + b[1] + " " + b[2] + "\n"+
@@ -393,8 +406,35 @@ nt3d = {
 				"endloop\n" +
 				"endfacet\n";
 		}
-		this.stl += "endsolid " + this.user_function.name + "\n";
+		stl += "endsolid " + name + "\n";
+		return stl;
+	},
+	go: function() {
+		// Remove any previous download links
+		var old_download_link = document.getElementById("nt3d_download");
+		if (old_download_link) {
+			old_download_link.parentNode.removeChild(old_download_link);
+		}
+
+		// Continue in a callback, so that there's not a stale download
+		// link hanging around while we process.
+		setTimeout(function() {
+
+		// Get params from form
+		var params = {};
+		for (var i = 0; i < this.user_params.length; i++) {
+			var as_string = this.form.elements["param"+i].value;
+			var as_num = +as_string;
+			params[this.user_params[i][0]] = isNaN(as_num) ? as_string : as_num;
+		}
+
+		this.points = this.user_function.call(null, params);
+
+		this.validate(this.points);
 
+		this.remove_degenerate_faces(this.points);
+
+		this.stl = this.to_stl(this.points, this.user_function.name);
 
 		// Offer result as download
 		var download_link = document.createElement("a");
@@ -406,7 +446,7 @@ nt3d = {
 		this.ui.appendChild(download_link);
 		setTimeout(function() { download_link.setAttribute("style", "-webkit-transition: background-color 0.4s; -moz-transition: background-color 0.4s; -o-transition: background-color 0.4s; -ms-transition: background-color 0.4s; transition: background-color 0.4s; background-color: inherit"); }, 0);
 
-		}).call(the_this); }, 0, this); // (We were in a callback this whole time, remember?)
+		}.bind(this), 0); // (We were in a callback this whole time, remember?)
 	},
 	framework: function (f, params) {
 		this.user_function = f;
@@ -436,7 +476,18 @@ nt3d = {
 			tr = document.createElement("tr");
 			table.appendChild(tr);
 			var td = document.createElement("td");
-			td.appendChild(document.createTextNode(params[i][0]));
+			var description;
+			if (params[i].length > 2) {
+				description = params[i][2];
+			} else {
+				description = params[i][0];
+				description = description[0].toUpperCase() + description.substr(1);
+				description = description.replace(/_(.)/g, function(_, c) {
+					return " " + c.toUpperCase();
+				});
+				description = description.replace("Num ", "Number of ");
+			}
+			td.appendChild(document.createTextNode(description));
 			tr.appendChild(td);
 			td = document.createElement("td");
 			var input = document.createElement("input");