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<div class="moz-cite-prefix">Adding support for STL makes a lot of
sense, though I did not find any references to a "standard". <br>
<br>
STL files contain just geometry information, while glTF and SRC
files (can) contain material or texture in additional to geometry.
Also glTF V1 and V2 files can contain Transform and multi-mesh
geometry. STL files are much more similar to TriangleSet node
(without color). There are extensions for adding color to an STL;
however, non of the formats are standardized and there are
conflicts between them. See
<a class="moz-txt-link-freetext" href="https://en.wikipedia.org/wiki/STL_(file_format)#Color_in_binary_STL">https://en.wikipedia.org/wiki/STL_(file_format)#Color_in_binary_STL</a>
for more information. It might make more sense to add a 'src'
attribute to the TriangleSet node that indicates an external
source for the definitions of the triangles and normals.<br>
<br>
One issue that would need to be address (at least in the text) is
that STL vertices are always positive. That is not in
contradiction with X3D, but is not necessarily aligned with the
common "mind-set" of the objected centered at the origin.<br>
<br>
Along the same lines, it would probably make sense to add a 'src'
attribute to the Transform and Group nodes to indicate that the
source is external. This extension would support glTF files.
Additional work on Physically Based Rendering and animation would
also be necessary to support glTF V2 files.<br>
<br>
Leonard Daly<br>
<br>
<br>
<br>
On 8/13/2017 6:35 PM, Don Brutzman wrote:<br>
</div>
<blockquote type="cite"
cite="mid:54c0b65e-e542-7396-f5c0-c5ef87e95d62@nps.edu">Good
article of general interest:
<br>
<br>
STL File Format for 3D Printing - Simply Explained | All3DP
<br>
June 13, 2017 bub Dibya Chakravorty
<br>
<a class="moz-txt-link-freetext" href="https://all3dp.com/what-is-stl-file-format-extension-3d-printing">https://all3dp.com/what-is-stl-file-format-extension-3d-printing</a>
<br>
<br>
Interesting thought question:
<br>
<br>
-if we follow Fraunhofer's SRC pattern and have both ExternalShape
and ExternalGeometry nodes,
<br>
- and now replace SRC with glTF 2, then
<br>
- might we similarly allow loading of STL models in ExternalShape
and ExternalGeometry nodes?
<br>
<br>
all the best, Don
<br>
</blockquote>
<p><br>
</p>
<div class="moz-signature">-- <br>
<font class="tahoma,arial,helvetica san serif" color="#333366">
<font size="+1"><b>Leonard Daly</b></font><br>
3D Systems & Cloud Consultant<br>
LA ACM SIGGRAPH Chair<br>
President, Daly Realism - <i>Creating the Future</i>
</font></div>
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