During our work on PAVEl we noticed, that some of the normal vectors in the STL-files we wanted to display pointed the wrong way. Finding those normal vectors in ASCII STL-files is a rather unpleasant task. In Binary STL-files it becomes quite impossible.

So we decided to create a small tool allowing us to preview STL-files (Surface Tesselation Language) and to repair those normal vectors. And the STLNormalSwitcher was born. It is programmed in C#.

STLNormalSwitcher displays a workpiece from an STL-file in a lighted OpenGl control allowing to rotate it and inspect it from all sides. Those triangles whose normal vectors point the wrong way can be easily identified, as they don’t reflect the light and thus appear darker. Triangles can be selected either directly in the visualization or in a list, that displays the normal vectors and the corresponding triangles, represented by their vertices. The selected normal vectors can then be inverted, so that they point the right way.

STLNormalSwitcher can open both ASCII and Binary STL-files and save changes in both formats. Thus it can also be used to convert ASCII STL-files to Binary STL-files and vice versa.

Because of the way the picking works, only 16.777.214 triangles can be displayed an picked. That number is only a theoretical limit, since the simple objects STLNormalSwitcher is intended for do not contain that many triangles and since it would require quite a lot of CPU-, GPU- and RAM-power.

What’s new: Version 2.0 of STLNormalSwitcher is capable of editing, adding and removing triangles.

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