X-Git-Url: http://git.scottworley.com/nt3d/blobdiff_plain/72eac64d07af484314745fd0e9466e0f94915684..1df99269ed4f25d4e70389ba70337ca62a545a5c:/nt3d.js diff --git a/nt3d.js b/nt3d.js index 0389946..d4e62f6 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[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"); @@ -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;