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<div class="moz-cite-prefix">Hi Albert et al,</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">Another option (at least for
user-friendly representations) would be to use converter symbology
in the field definition. For example, right now rotations are
represented by</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix"><i><tt>normalized-vector angle</tt></i></div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">where <i><tt>normalized-vector</tt></i>
is a 3-space vector that has been normalized that represents the
axis of rotation; and <tt><i>angle</i></tt> is the angle of
rotation.</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">A set of symbolic converter functions
could be specified that allowed the user to specify the rotation
is a number of different manners. These functions would accept the
rotation values and convert them into a standardized internal form
(or default input form, depending on the particular browser).<br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">For example, converter functions could
be defined for Axis-Angle (default), Euler, and Quaternion. The
rotation formats would then be equivalent.</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix"><tt> AXIS-ANGLE (normalized-vector
angle)</tt></div>
<div class="moz-cite-prefix"><tt> EULER (angleX angleY angleZ)</tt></div>
<div class="moz-cite-prefix"><tt> QUATERNION (qw qx qy qz)</tt></div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">All would be legal rotation field
values and would convert to the same internal format.</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">This would work when the X3D encoding
was string based (XML or Classic VRML). The binary encoding would
need to process the input (which converts do now) to a
standard/default format.<br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">This allows the user interface encoding
to specify something that is clear and nice to the user; while
maintaining a standardized internal format. Note that the function
name is part of the value, so changing the value would require a
function (or use of the default).</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">I implemented this in XSeen, though it
hasn't documented yet. In addition to rotations, I use something
similar for colors (fractional, value (decimal), byte (hex),
labeled (white, red, green, etc.)). For both of these, I drew my
inspiration from CSS and their specification of colors and other
data values.</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">Essentially all of the fundamentals of
X3D were taken from VRML, which was taken from OpenGL pre-1997
with a number of features added from those long-ago years.
Computation was expensive then so user-niceties were sometimes
compromised in favor of efficiencies.</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix"><br>
Leonard Daly<br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<blockquote type="cite"
cite="mid:AM0PR0402MB380951C0F0A71821C6738C61DA890@AM0PR0402MB3809.eurprd04.prod.outlook.com">
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<span><span style="display:inline!important;
background-color:rgb(255,255,255); font-size-adjust:none">"So
the term euler would replace the term rotation and also be a
different datatype than rotation"</span></span></div>
<div style="color:rgb(0,0,0);
font-family:Calibri,Helvetica,sans-serif; font-size:12pt">
<span><br>
</span></div>
<div style="color:rgb(0,0,0);
font-family:Calibri,Helvetica,sans-serif; font-size:12pt">
<span>Yes, 'euler' would be complementary, an alternative way,
to set the initial orientation. To avoid Gimbals lock, one
should of course use quaternions for dynamic rotations.</span></div>
<div style="color:rgb(0,0,0);
font-family:Calibri,Helvetica,sans-serif; font-size:12pt">
<span><br>
</span></div>
<div style="color:rgb(0,0,0);
font-family:Calibri,Helvetica,sans-serif; font-size:12pt">
I think t<span>he sequence of the individual numbers for the
angles and their sign should correspond to the x y z axes as
defined by X3D. I don't really have an opinion on the yaw,
pitch roll terms: -z seems a natural gaze direction for this. </span></div>
<div style="color:rgb(0,0,0);
font-family:Calibri,Helvetica,sans-serif; font-size:12pt">
<span><br>
</span></div>
<div style="color:rgb(0,0,0);
font-family:Calibri,Helvetica,sans-serif; font-size:12pt">
<span>Albert Jan Wonnink </span></div>
<div>
<div style="color:rgb(0,0,0);
font-family:Calibri,Helvetica,sans-serif; font-size:12pt">
<br>
</div>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt"
face="Calibri, sans-serif" color="#000000"><b>Van:</b>
x3d-public <a class="moz-txt-link-rfc2396E" href="mailto:x3d-public-bounces@web3d.org"><x3d-public-bounces@web3d.org></a> namens
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<a class="moz-txt-link-rfc2396E" href="mailto:x3d-public-request@web3d.org"><x3d-public-request@web3d.org></a><br>
<b>Verzonden:</b> maandag 7 januari 2019 14:44<br>
<b>Aan:</b> <a class="moz-txt-link-abbreviated" href="mailto:x3d-public@web3d.org">x3d-public@web3d.org</a><br>
<b>Onderwerp:</b> x3d-public Digest, Vol 118, Issue 15</font>
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Today's Topics:<br>
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1. Re: Euler rotation (Joseph D Williams)<br>
<br>
<br>
----------------------------------------------------------------------<br>
<br>
Message: 1<br>
Date: Mon, 7 Jan 2019 05:43:28 -0800<br>
From: Joseph D Williams <a class="moz-txt-link-rfc2396E" href="mailto:joedwil@earthlink.net"><joedwil@earthlink.net></a><br>
To: Albert Jan Wonnink <a class="moz-txt-link-rfc2396E" href="mailto:awonnink@hotmail.com"><awonnink@hotmail.com></a>,
John Carlson<br>
<a class="moz-txt-link-rfc2396E" href="mailto:yottzumm@gmail.com"><yottzumm@gmail.com></a>,
<a class="moz-txt-link-rfc2396E" href="mailto:vmarchetti@kshell.com">"vmarchetti@kshell.com"</a><br>
<a class="moz-txt-link-rfc2396E" href="mailto:vmarchetti@kshell.com"><vmarchetti@kshell.com></a>, X3D-Public
<a class="moz-txt-link-rfc2396E" href="mailto:x3d-public@web3d.org"><x3d-public@web3d.org></a><br>
Subject: Re: [x3d-public] Euler rotation<br>
Message-ID:
<a class="moz-txt-link-rfc2396E" href="mailto:E1ggVBd-0003vy-Se@elasmtp-curtail.atl.sa.earthlink.net"><E1ggVBd-0003vy-Se@elasmtp-curtail.atl.sa.earthlink.net></a><br>
Content-Type: text/plain; charset="utf-8"<br>
<br>
From: Albert Jan Wonnink<br>
Sent: Monday, January 7, 2019 2:03 AM<br>
To: John Carlson; Joseph D Williams;
<a class="moz-txt-link-abbreviated" href="mailto:vmarchetti@kshell.com">vmarchetti@kshell.com</a>; X3D-Public<br>
Subject: Re: [x3d-public] Euler rotation<br>
<br>
? Hi Joseph,<br>
<br>
? Thank you for your reply. Just to be sure: the context
I meant to discuss is about having a convenient
attribute in the declarative syntax, say 'euler', to set
the initial orientation of the transform, so anyone can
use either 'rotation' or 'euler'.<br>
? <br>
? <transform euler="20 40 10" ><br>
? <br>
<br>
Fine, Albert, <br>
So the term euler would replace the term rotation and
also be a different datatype than rotation?
<br>
The important technical and usage detail is accepting
quaternions since probably the preferred internal form.<br>
The main thing about degrees is that they won?t always
work. That is why Euler moved on. If you are making
video frames, then maybe ok to author or capture frame
data in degrees but when you want to have some realtime
or variabletime fun, then interpolation may not operate
as expected or at all. <br>
<br>
? So I interpreted Vince's $yaw, $pitch and $roll to be
just placeholders, for manual substitution.?<br>
<br>
Thoughts about the use of pitch yaw roll names for the x
y z rotation/orientation axes?
<br>
Just as a memory aid of course. <br>
I described it as I found it in viewpoint where the
default is gaze -z and hanim joint animations where the
default is gaze +z.
<br>
<br>
? You are right using this with either radians or
degrees would be equally simple.?<br>
<br>
Most simple and reliable using the x3d form thinking
with radians, no doubt. The x3d recognition of
quaternions would improve x3d capability by being even
more simple and reliable and also giving improved level
of validation for rotation and orientation values.
<br>
<br>
<br>
? Regards,<br>
? Albert Jan?<br>
<br>
Thanks for the thoughts, <br>
Joe<br>
<br>
?<br>
<br>
??<br>
From: Joseph D Williams<br>
Sent: Sunday, January 6, 2019 7:20 PM<br>
To: Albert Jan Wonnink; <a class="moz-txt-link-abbreviated" href="mailto:vmarchetti@kshell.com">vmarchetti@kshell.com</a>;
X3D-Public<br>
Subject: Re: [x3d-public] Euler rotation<br>
?<br>
Hi Albert and All, <br>
When you use euler (or Tait-Bryan) angles for a while
you will find that you get problems.
<br>
Actually there is plenty of writing about the details
maybe even in the x3d or hanim archives and widely on
the web.<br>
?<br>
In addition, when you create or edit the things much
then you will find it is actually a lot easier to use
quats or axis-angle radians. In general, for degrees,
maybe your editing system may offer as a learning tool
if radian is really an elementary block to learning, but
really, never in the user code due to misleading
simplicity and what ?cha finally gonna tell ?em when the
gimbals lock?
<br>
?<br>
? <Transform DEF="yaw-rotation" rotation="0 0 1
$yaw"><br>
? <Transform DEF="pitch-rotation" rotation="0 1 0
$pitch"><br>
? <Transform DEF="roll-rotation" rotation="1 0 0
$roll"><br>
?<br>
Besides the fact that a variable is not allowed there <br>
(maybe use a prototype if you need a variable?) <br>
I don't think your naming of yaw and pitch and roll is
reasonable for x3d. <br>
?<br>
For default transform rotation 0 0 1 0, sit on it and
face +z and find +y is up and +x is left.
<br>
then fly the thing using pitch and yaw and roll.<br>
The x3d axis-angle parameters are most likely pitch yaw
roll then the scale, <br>
and I think the same order for quaternions, except where
the 'scale' is placed and the special limits for values.
<br>
?<br>
Why not try the following:<br>
?<br>
DEF Pitch OrientationInterpolator { <br>
key [ 0, 0.25 0.5, 0.75 1 ] <br>
keyValue [ 0 0 1 0, 1 0 0 1.5, 0 0 1 0, -1 0 0 1.5, 0 0
1 0 ] }<br>
?<br>
DEF Yaw OrientationInterpolator { key [ 0, 0.25 0.5,
0.75 1 ] <br>
keyValue [ 0 0 1 0, 0 1 0 1.5, 0 0 1 0, 0 -1 0 1.5, 0 0
1 0 ] }<br>
?<br>
DEF Roll OrientationInterpolator { <br>
key [ 0, 0.25 0.5, 0.75 1 ] <br>
keyValue [ 0 0 1 0, 0 0 1 1.5, 0 0 1 0, 0 0 1 1.5, 0 0 1
0 ] }<br>
?<br>
Thanks and Best,<br>
Joe<br>
?<br>
From: Albert Jan Wonnink<br>
Sent: Sunday, January 6, 2019 2:25 PM<br>
To: <a class="moz-txt-link-abbreviated" href="mailto:vmarchetti@kshell.com">vmarchetti@kshell.com</a>; X3D-Public<br>
Subject: Re: [x3d-public] Euler rotation<br>
?<br>
Thanks Vince, for your reply.?<br>
?<br>
As long as the angles and X3D code is? generated by code
one can of course easily calculate the individual
parameters for a quaternion. But during the testing of
our experimental Unity based browser, and preparing
scenes for that, I found it very easy to extend the
transform specification with a degree-based Euler
attribute (Tait-Bryan would also have worked).<br>
?<br>
The current system still makes it relatively difficult
to manually apply an angle of the most used fractions of
PI, doesn't it?<br>
?<br>
I guess this issue must have been discussed in one of
the early days of the X3D specification. But it seems to
me a lost chance to make it more convenient.<br>
?<br>
Regards<br>
?<br>
?<br>
Albert Jan Wonnink<br>
?<br>
?<br>
<br>
Van: <a class="moz-txt-link-abbreviated" href="mailto:vmarchetti@kshell.com">vmarchetti@kshell.com</a> <a class="moz-txt-link-rfc2396E" href="mailto:vmarchetti@kshell.com"><vmarchetti@kshell.com></a><br>
Verzonden: zondag 6 januari 2019 22:49<br>
Aan: Albert Jan Wonnink; X3D-Public<br>
Onderwerp: Re: [x3d-public] Euler rotation <br>
?<br>
There is no single node Euler angle alternative
representation of a rotation transform defined in the
current (v 3.3) X3D standard.<br>
?<br>
You can get an easier to edit representation of Euler
angle rotation (specifically the Tait-Bryan
angles,?<a class="moz-txt-link-freetext" href="https://en.wikipedia.org/wiki/Euler_angles#Tait%E2%80%93Bryan_angles">https://en.wikipedia.org/wiki/Euler_angles#Tait%E2%80%93Bryan_angles</a>,
commonly used for vehicle oriented<br>
with respect to the horizon, by nesting 3 Transforms:<br>
?<br>
<Transform DEF="yaw-rotation" rotation="0 0 1
$yaw"><br>
<Transform DEF="pitch-rotation" rotation="0 1 0
$pitch"><br>
<Transform DEF="roll-rotation" rotation="1 0 0
$roll"><br>
<!-- put vehicle model here --><br>
<Shape>...</Shape><br>
</Transform><br>
</Transform><br>
</Transform><br>
?<br>
where for $yaw, $pitch, $roll you need to substitute the
numerical value of the rotation angle in radians.<br>
?<br>
?<br>
Vince Marchetti<br>
?<br>
On Jan 6, 2019, at 12:53 PM, Albert Jan Wonnink
<a class="moz-txt-link-rfc2396E" href="mailto:awonnink@hotmail.com"><awonnink@hotmail.com></a> wrote:<br>
?<br>
Is there, or should there be, an Euler alternative for
the transform 'rotation' property? This makes direct x3d
code editing much easier.<br>
?<br>
Regards,<br>
?<br>
?<br>
Albert Jan Wonnink?<br>
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?<br>
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<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 Past Chair<br>
President, Daly Realism - <i>Creating the Future</i>
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