<div dir="auto">Note: I have a hypothesis why this happened. </div><div dir="auto"><br></div><div dir="auto">The drawing presented at SpotLight description (it is the same in all X3D versions) shows a situation when beamWidth < cutOffAngle. The drawing shows a situation when these is smooth falloff between beamWidth and cutOffAngle. Maybe someone thought that defaults do not match this drawing, ans thus reversed the defaults.</div><div dir="auto"><br></div><div dir="auto">I would say that the drawing just doesn't, and never meant to, show the default state. It just shows an example state that is possible.</div><div dir="auto"><br></div><div dir="auto">Regards,</div><div dir="auto">Michalis</div><div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">W dniu pon., 14.02.2022 o 05:10 Michalis Kamburelis <<a href="mailto:michalis.kambi@gmail.com">michalis.kambi@gmail.com</a>> napisał(a):<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;padding-left:1ex;border-left-color:rgb(204,204,204)">Hi,<br>
<br>
I just noticed an alarming regression at SpotLight definition across<br>
X3D versions.<br>
<br>
1. In VRML 97, X3D 3.0, 3.1 and 3.2 the default values are:<br>
<br>
- beamWidth pi/2<br>
- cutOffAngle pi/4<br>
<br>
This means that there is no smooth falloff from beamWidth to<br>
cutOffAngle. Spot light has multiplier = 1 in range 0...pi/4, and then<br>
it's zero outside of pi/4.<br>
<br>
I think this is the good definition. It makes sense as default.<br>
<br>
See:<br>
<br>
- VRML 97: <a href="http://tecfa.unige.ch/guides/vrml/vrml97/spec/part1/nodesRef.html#SpotLight" rel="noreferrer" target="_blank">http://tecfa.unige.ch/guides/vrml/vrml97/spec/part1/nodesRef.html#SpotLight</a><br>
<br>
- X3D 3.0: <a href="https://www.web3d.org/documents/specifications/19775-1/V3.0/Part01/components/lighting.html#SpotLight" rel="noreferrer" target="_blank">https://www.web3d.org/documents/specifications/19775-1/V3.0/Part01/components/lighting.html#SpotLight</a><br>
<br>
- X3D 3.1: this version seems to be published only as "diff from X3D<br>
3.0", and it has no change regarding SpotLight, see<br>
<a href="https://www.web3d.org/documents/specifications/19775-1/V3.1/Part01/components/lighting.html" rel="noreferrer" target="_blank">https://www.web3d.org/documents/specifications/19775-1/V3.1/Part01/components/lighting.html</a><br>
<br>
- X3D 3.2: <a href="https://www.web3d.org/documents/specifications/19775-1/V3.2/Part01/components/lighting.html#SpotLight" rel="noreferrer" target="_blank">https://www.web3d.org/documents/specifications/19775-1/V3.2/Part01/components/lighting.html#SpotLight</a><br>
<br>
2. In X3D 3.3 and 4.0 however, the defaults are reversed:<br>
<br>
- beamWidth pi/4<br>
- cutOffAngle pi/2<br>
<br>
This makes a different behavior, and one that is IMHO less expected.<br>
cutOffAngle pi/2 means that "total angle of spotlight" is pi, 180<br>
degrees. This is possible, but unexpected as default for a spot light.<br>
It's a very wide light, effectively shining on half of 3D space.<br>
<br>
See:<br>
<br>
- X3D 3.3: <a href="https://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components/lighting.html#SpotLight" rel="noreferrer" target="_blank">https://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components/lighting.html#SpotLight</a><br>
<br>
- X3D 4.0 draft:<br>
<a href="https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-CD1/Part01/components/lighting.html#SpotLight" rel="noreferrer" target="_blank">https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-CD1/Part01/components/lighting.html#SpotLight</a><br>
<br>
What others do?<br>
<br>
- Castle Game Engine and view3dscene always followed AD 1. I didn't<br>
even know that there was a change to this in X3D 3.3.<br>
<br>
- InstantReality (at least docs) also follows AD 1, looking at<br>
<a href="https://doc.instantreality.org/documentation/nodetype/SpotLight/" rel="noreferrer" target="_blank">https://doc.instantreality.org/documentation/nodetype/SpotLight/</a><br>
<br>
- X3DOM (at least docs) is confused, judging from<br>
<a href="https://doc.x3dom.org/author/Lighting/SpotLight.html" rel="noreferrer" target="_blank">https://doc.x3dom.org/author/Lighting/SpotLight.html</a> . They say that<br>
both cutOffAngle and beamWidth are both pi/2 by default, which is not<br>
consistent with any X3D version.<br>
<br>
I didn't test InstantReality or X3DOM in practice, only looked at docs now.<br>
<br>
Proposal: let's fix X3D 4.0. Revert the defaults to what was in X3D 3.2:<br>
<br>
- beamWidth pi/2<br>
- cutOffAngle pi/4<br>
<br>
Unless someone knows a good reason for change in X3D 3.3, I'm tempted<br>
to call this just a simple human mistake when someone was editing X3D<br>
3.3.<br>
<br>
Regards,<br>
Michalis<br>
</blockquote></div></div>