16 Posts
As a ldraw user, I also use ldraw parts in Blender, and to make the comparison, I exported the plate 1x1 round with collada and wavefront, and compared it with the one from ldraw. Apart the fact that ldraw are 10 times small, that I can corrected with a scale operation, there are still some differences. I checked with the parts showed here : http://www.mecabricks.com/en/forum/topic/15 , and the measurements are the same, exactly identical with the result from ldraw to Blender.
So, I guess there is a kind of corruption in the export methods, but is it from blender to json, or from json to collada / wavefront, I don't know. I already saw this corruption with some parts exported from 3DS max, but I don't remember the output format (json or wavefront). Maybe a comparison between the original mecabricks blender creation and the export version reimport in blender will be great first step to understand where the problem come from.
12 May 2015, 10:07
3085 Posts

I'm not too sure I understand the issue correctly.
I know there is a factor 10 between ldraw parts and my parts (I use 1 Blender unit for 1mm) which is easy to correct as you said.

However, detail dimensions for ldraw and mecabricks shall be different. For instance, they use 1.6mm stud height where I use 1.8mm. Besides as per the post you quoted, I slightly reduce the overall dimensions to leave a gap when parts are assembled in mecabricks. e.g. 7.92mm instead of 8mm for the 1x1 brick width. Therefore you shall not get exactly the same dimensions for a same part coming from ldraw or mecabricks.

I did a quick trial to compare my parts from original Blender files and exported in collada or obj from mecabricks.
Parts tested: 3024 Plate 1X1 and 4073 Round Plate 1X1. All 3 instances of each part design match perfectly.
So parts don't seem to be impacted by the different 3D format conversions (Blender > json > collada or obj).

Let me know if I did not correctly understand your question.
13 May 2015, 03:49
16 Posts
You perfectly answered my question ^^ . The dimensions modifications you indicate, apply to a round plate 1x1, make it match nearly perfectly, so it's not a corruption, but a real difference. Thanks for the answer.

With this conversion method, I guess you can easily transform nearly all the ldraw parts. I have a blend file with more than 600 parts already imported, if you want
13 May 2015, 08:17
3085 Posts
So I actually understood properly

I'd me happy to have a look at your file to see if I can easily tweak them to fit mecabricks dimension system.
14 May 2015, 11:09
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