Zero surface normals in STL files about jsc3d

[GoogleCodeExporter]

Thanks Steve! I'll fix this as soon as possible.

Original comment by [email protected] on 20 Jul 2013 at 4:15

[GoogleCodeExporter]

Thanks for the swift response!

To be completely clear, I only tested the problem with binary STL files from 
blender - but from a quick look at the code, I believe that ASCII STL's must 
have the same problem.

STL's are frequently used for controlling machine tools like 3D printers and 
CNC milling machines that don't care about surface normals, colors or anything 
else other than the triangle vertices - so it's fairly common for STL exporters 
to fail to write the normal vector and for STL importers to recreate them from 
the triangle edges.

The STL file format *really* sucks - it's horrifying that it ever became such a 
ubiquitous standard for machine tools!

Original comment by [email protected] on 20 Jul 2013 at 1:20

[GoogleCodeExporter]

Thanks for the detailed explanation!

This bug has fixed by checking some normals loaded from an STL file. If the 
normal length equals to 0, the face normal buffer will be set to null so that 
they can be automatically calculated when mesh is initialized.

I'll commit the patch to the respository soon.

Original comment by [email protected] on 21 Jul 2013 at 6:10