Added source code

tests/bezier.scad

@@ -0,0 +1,83 @@
+//
+// NopSCADlib Copyright Chris Palmer 2018
+// nop.head@gmail.com
+// hydraraptor.blogspot.com
+//
+// This file is part of NopSCADlib.
+//
+// NopSCADlib is free software: you can redistribute it and/or modify it under the terms of the
+// GNU General Public License as published by the Free Software Foundation, either version 3 of
+// the License, or (at your option) any later version.
+//
+// NopSCADlib is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+// without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+// See the GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along with NopSCADlib.
+// If not, see <https://www.gnu.org/licenses/>.
+//
+include <../core.scad>
+use <../utils/bezier.scad>
+use <../utils/sweep.scad>
+use <../utils/annotation.scad>
+
+function find_min_z(path, i = 1, best_i = 0) =
+    i >= len(path) ? best_i
+                   : find_min_z(path, i + 1, path[i].z < path[best_i].z ? i : best_i);
+
+module beziers() {
+    //
+    // Make Bezier control points to give specified length
+    //
+    control_points = adjust_bezier_length([[0, 0, 100], [0, 0, 0], [200, 0, 20], [100, -100, 50]], 250);
+    //
+    // Draw control points
+    //
+    color("green")
+        for(p = control_points)
+            translate(p)
+                sphere(1);
+    //
+    // Lines joining the control points
+    //
+    color("red")
+        sweep(control_points, circle_points(0.5, $fn = 64));
+    //
+    // Bezier curve path from control points
+    //
+    curve = bezier_path(control_points);
+    //
+    // Draw the curve
+    //
+    sweep(curve, circle_points(2, $fn = 64));
+    //
+    // Length computed from control points
+    //
+    length = bezier_length(control_points);
+    //
+    // Length computed from curve
+    //
+    length2 = path_length(curve);
+    assert(str(length) == str(length2), str(length, " ", length2));
+    //
+    // Minimum Z
+    //
+    min_z = bezier_min_z(control_points);
+    i = find_min_z(curve);
+    assert(str(min_z) == str(curve[i].z));
+
+    color("blue") {
+        translate(curve[i] + [0, 0, 2])
+            arrow();
+
+        translate(curve[i] - [0, 0, 2])
+            vflip()
+                arrow();
+    }
+
+    translate(control_points[1] - [0, 0, 2])
+        label(str("bezier_length = ", length, ", bezier_min_z = ", bezier_min_z(curve)), valign = "top");
+}
+
+if($preview)
+    beziers();