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Decreasing poly count on models - Printable Version

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Re: Decreasing poly count on models - Michael Heidemann - 2013-11-23

Very interesting and a good point to start or add to already existing techniques. Thanks for sharing.

Re: Decreasing poly count on models - Steffen - 2013-11-23

I thought always that such an algorithm was used inside windz.exe
which can auto-BFC a part.
Am I wrong?

Re: Decreasing poly count on models - Michael Heidemann - 2013-11-23

I think yes, but as we do not have the source code for windz we do not know.

Re: Decreasing poly count on models - Philippe Hurbain - 2013-11-24

Here is a quick description by Ildefonso, when we discussed about issues that Windz has with open (eg. subparts) structures:
Quote:The ray tracing algorithm casts rays randomly. It counts the number of hits that were done by both sides of the triangles/quads and if this difference is bigger than 70% it assumes that this is the outside of the triangle. Once it finds the outside of one triangle, it finds its triangles/quads neighbors and set the same orientation for them.
My idea was to remove this randomness letting the user to set the direction that the rays will follow. So, one could choose if all the rays would be cast from top to bottom, from right to left and so on. I think that even with this algorithm, we will have some cases that it will not work, but this should help in simple cases like flat parts.

Re: Decreasing poly count on models - Michael Heidemann - 2013-11-24

Thanks for that.
His suggestion for flat parts works, I have already coded the same but throw it away because only some parts are really flat and those can be easily corrected nowadays with MLCad (swap).

RE: Decreasing poly count on models - Michael Horvath - 2017-12-22

(2013-11-23, 10:14)Antonio Cortés Carrillo Wrote: A very very long time ago (2004), i implemented a similiar algorithm that detects and removes the inner parts of the model.

If you are interesting, can find it here:


Is not the buf3d, is much older and for that reason:
* Does not properly read all 3D Ldraw models.
* Do not use GPU (but works very fast ... )
* Well .... sure there are many bugs that buf3d already solved Smile

For use, these are the steps to follow:
- Import->Ldraw Model (I will ask the library directory)
- Optimize-> Select Objects Ocludded
- They will leave many options without touching it will be fine (9/16 iterations)
- After the process, the internals parts appear selected
- Selected-> Show Selection Only (Optional)
- Selected-> Remove Selected

Removes over 50% triangles, easily Smile

Bump. Does this tool output to the ldraw format too? Or something else?