<div dir="auto"><div><div class="gmail_extra"><br><div class="gmail_quote">On Mar 6, 2017 8:13 PM, "Don Brutzman" <<a href="mailto:brutzman@nps.edu">brutzman@nps.edu</a>> wrote:<br type="attribution"><blockquote class="quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">...<br>
I think it best not to mention negative scale as part of ccw field per se, or any geometry/normal definitions, because the negative scaling value is not defined there. Rather we can define how a Transform negative scale affects already-defined geometry coordinates and normals. Spec sayeth:<br>
<br>
10.4.4 Transform<br>
<a href="http://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components/group.html#Transform" rel="noreferrer" target="_blank">http://www.web3d.org/documents<wbr>/specifications/19775-1/V3.3/<wbr>Part01/components/group.html#T<wbr>ransform</a><br>
<br>
which says<br>
<br>
"The scale field specifies a non-uniform scale of the coordinate system. Scale values may have any value: positive, negative (indicating a reflection), or zero. A value of zero indicates that any child geometry shall not be displayed."<br>
<br>
So perhaps this question reduces to whether a Transform reflection is sufficiently well defined?<div class="elided-text"><br>
</div></blockquote></div></div></div><div dir="auto"><br></div><div dir="auto">Yes, I think this a good way to pose the question.</div><div dir="auto"><br></div><div dir="auto">I think the problem in the stack overflow question and perhaps in three is that normals may be generated after the reflection of vertices ?</div><div dir="auto"><br></div><div dir="auto">I would not have anticipated that this could be considered in an implementation but if this is really the issue then it is probably worth to tighten the definition of reflection in the spec.</div><div dir="auto"><br></div><div dir="auto">I may ask this question in the three.js issue.</div><div dir="auto"><br></div><div dir="auto">Andreas</div><div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto"><div class="gmail_extra"><div class="gmail_quote"><blockquote class="quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="elided-text"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><br>
</blockquote>
<br></div>
all the best, Don<font color="#888888"><br>
-- <br>
Don Brutzman Naval Postgraduate School, Code USW/Br <a href="mailto:brutzman@nps.edu" target="_blank">brutzman@nps.edu</a><br>
Watkins 270, MOVES Institute, Monterey CA 93943-5000 USA <a href="tel:%2B1.831.656.2149" value="+18316562149" target="_blank">+1.831.656.2149</a><br>
X3D graphics, virtual worlds, navy robotics <a href="http://faculty.nps.edu/brutzman" rel="noreferrer" target="_blank">http://faculty.nps.edu/brutzma<wbr>n</a><br>
</font></blockquote></div><br></div></div></div>