// 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
}
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-7) {
+ 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
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;
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 ++;
}
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"+
"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(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;
+ }
+
+ this.points = this.user_function.apply(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");
projects / nt3d / blobdiff