Explicitly bounds-check in angle_between()

[nt3d] / nt3d.js

diff --git a/nt3d.js b/nt3d.js
index 28766983fe33341b262ee572f4a09fc01d917d4c..038994678f9328de72fca780f4a8b639a58e915b 100644 (file)
--- a/nt3d.js
+++ b/nt3d.js
@@ -259,7 +259,14 @@ nt3d = {
                        point[2] + offset[2]];
        },
        angle_between: function(a, b) { // a and b must be unit vectors
-               return Math.acos(this.dot(a, b));
+               var the_dot = this.dot(a, b);
+               if (the_dot <= -1) {
+                       return Math.PI;
+               }
+               if (the_dot >= 1) {
+                       return 0;
+               }
+               return Math.acos(the_dot);
        },
        rotate_about_origin: function(points, axis, angle) { // axis must be a unit vector
                // From http://inside.mines.edu/~gmurray/ArbitraryAxisRotation/
@@ -297,6 +304,17 @@ nt3d = {
                                angle),
                        center);
        },
+       point_equal: function(a, b, epsilon) {
+               return Math.abs(a[0] - b[0]) < epsilon &&
+                      Math.abs(a[1] - b[1]) < epsilon &&
+                      Math.abs(a[2] - b[2]) < epsilon;
+       },
+       degenerate_face_epsilon: 1e-10,
+       is_degenerate: function(a, b, c) {
+               return this.point_equal(a, b, this.degenerate_face_epsilon) ||
+                      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");
@@ -318,14 +336,51 @@ nt3d = {
 
                // Run user_function
                this.points = this.user_function.apply(null, params);
+
+               // Do a little validation
                if (this.points.length % 3 != 0) {
                        alert("Points list length not divisble by 3!");
                }
-               var n = this.points.length / 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++) {
+                       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])) {
+                                               nan_count++;
+                                               nan_in_point = true;
+                                               nan_in_face = true;
+                                       }
+                               }
+                               if (nan_in_point) nan_point_count ++;
+                       }
+                       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).");
+               }
+
+               // Remove degenerate faces
+               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);
+                               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 < n; i++) {
+               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];