Wednesday, July 23, 2008

STL taking shape

Just a quick note tonight about my progress with STL export.  I spent some of this afternoon mocking up the export and it went just as easily as I expected.  I nearly finished the whole thing, just need to implement Trimmed Surface tessellation, which I think I can knock out tomorrow.  So, hopefully by end of day tomorrow, we will have nicely working STL output.  As soon as I can I will post a sample output file on the download page.  If you want to try it out tonight, from the Part Designer screen just press 'x' and output.stl will be written to the same directory as the Wildcat root directory.  Obviously, we will need to eventually get a proper window to choose an output file name etc.

One question for those that know STL.  The top level object in the STL file appears to be "solid", with facets below that.  It is very easy to generate multiple separate solid bodies in Wildcat, how should I handle this?  Can you have more than one "solid" in a single STL file?  Should the user have to select a single body in Wildcat?  If anyone knows, please post a comment.



Anonymous said...

I tried to read a bit up on the stl file format. Art of illusion and blender exports in binary stl format.
(A simple python script would be enough to convert between binary and ascii format. Dont brother with it).

I have read on many web pages and all of them assume, one solid and one endsolig tag in a file.

And as the stl file does not contain a coordinate system, all coordinates are in absolute value. So if an stl file contains multiple objects, it will placed in absolute position, and it is no easy way to move in space.

And in practice I think reprap print one object a time.
Or one object in multiple copies shifted equally on the table.

So I think in practice it would be nice to move the model to the origo, and export it, one object at a time. Maybe rotate it too, if it more easy to print it physically.

All in all, I think it should only export one object at once.


Anonymous said...

Ok blender only export the selected object into the stl file.

I think this is the right way.

In summary I think an stl file could contain only one object.