MCAD/involute_gears.scad problem in F5 mode.

[knuds]

I use OpenSCAD 2011.04.27 on Ubuntu.

It renders OK with F6 but F5 appear strange.

See
http://all-technology.com/openscad-F5.png
and
http://all-technology.com/openscad-F6.png

The script I use is:
include <MCAD/involute_gears.scad>;

teeth=11;
dist=150;

translate([dist,dist,0]) rotate([0,90,90]) bevel_gear_pair(gear1_teeth = teeth, gear2_teeth = teeth);
translate([dist,-dist,0]) rotate([0,-90,90]) bevel_gear_pair(gear1_teeth = teeth, gear2_teeth = teeth);
translate([-dist,dist,0]) rotate([0,-90,-90]) bevel_gear_pair(gear1_teeth = teeth, gear2_teeth = teeth);
translate([-dist,-dist,0]) rotate([0,90,-90]) bevel_gear_pair(gear1_teeth = teeth, gear2_teeth = teeth);

[daid]

By any chance did you get a warning when you started OpenSCAD? Because that looks like the "thrown together" renderer, which doesn't do any "substractive" rendering. The F5 needs some fancy OpenGL features that your video card (or the ubuntu driver) most like doesn't support.

It says "OpenCSG rendering disabled" in the log. At which point this output is to be expected.

[kintel]

It looks like this is a problem with the involute_gears library. If I patch involute_gears.scad as follows, this works for me.
Note: Too many gears causes OpenCSG to be turned off as it would take a lot of time to render. Rendering one gear for testing is enough to demonstrate the mentioned bug.

diff --git a/involute_gears.scad b/involute_gears.scad
index eaf9051..fd80efe 100644
--- a/involute_gears.scad
+++ b/involute_gears.scad
@@ -286,7 +286,7 @@ module involute_bevel_gear_tooth (
[side2_point2[0],side2_point2[1],0],
[side2_point1[0],side2_point1[1],0],
[0.1,0,0]],

•                                       triangles=[[0,1,2],[0,2,3],[0,3,4],[0,5,1],[1,5,2],[2,5,3],[3,5,4],[0,4,5]]);
  

•                                     triangles=[[0,2,1],[0,3,2],[0,4,3],[0,1,5],[1,2,5],[2,3,5],[3,4,5],[0,5,4]]);
                          }
                  }
          }
  

[kintel]

This has been fixed in MCAD