Re: HDR / PBR / compositor info

Patrick Callahan <[email protected]> Sun, 12 Jul 2026 08:57:37 -0400
Newsgroups gmane.games.flightgear.devel
Message-ID <CACt=GQokeDeqVFBJTsbUbtjz6rqbtwtK921CU_js9rMWcqU6FA@mail.gmail.com>
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Isn't the transformation from one coordinate system to another a task for
the code that loads a model from a file?


On Fri, Jul 10, 2026 at 2:41=E2=80=AFAM Josh Davidson <joshdavidson2000@out=
look.com>
wrote:

> Well, wiki also says:
> *Transform -> +Y up*
> Make sure to keep this *OFF*. Blender uses a +Z up convention like
> FlightGear, so we do not adhere to the glTF standard (+Y up).
>
> So does that mean glTF's will be +Z up?
>
> --
> Josh Davidson
> ------------------------------
> *From:* Josh Davidson <[email protected]>
> *Sent:* Friday, July 10, 2026 01:32
> *To:* FlightGear developers discussions <
> [email protected]>
> *Subject:* Re: [Flightgear-devel] HDR / PBR / compositor info
>
> About next...
>
> https://wiki.flightgear.org/Howto:Convert_from_AC3D_to_glTF
>
> This doesn't make sense. In the AC3D system, Y is up/down, in FG Z is
> up/down, in glTF, Y is up/down. Someone made a conscious choice to make Z
> up/down in FlightGear a VERY long time ago.
>
> Can't that choice be duplicated so we don't end up with having to rework
> 1000s of lines of code to move to glTF? Also wouldn't reworking it mean
> coordinate schemes are now different for the model vs the FDE/etc? If so,
> that would be horrible... but as would having to swap axis' on the FDE's =
as
> that would ruin everything.
>
> So emotional annoyance aside, wouldn't it be possible to simply swap -Y
> and Z again on glTF just like is already done on AC3D? Reminder, in AC3D,=
 Y
> is up/down... no idea why when blender got involved that changed to Z, or
> why FG moved it to Z as well.
>
> Basically, it would be so cool if we could reduce the amount of
> "unnecessary breaking" occurring in the glTF migration.
>
> I would also like to ask why the emission animation was removed? What
> about existing AC3D models? What if I need to make something light up
> conditionally? What do I do then?
>
> In all honesty, I'm really not thrilled about how much reworking I'll hav=
e
> to do when next releases if things continue this way...
>
> --
> Josh Davidson
> ------------------------------
> *From:* Wayne Bragg <[email protected]>
> *Sent:* Sunday, June 7, 2026 23:18
> *To:* [email protected] <
> [email protected]>
> *Subject:* Re: [Flightgear-devel] HDR / PBR / compositor info
>
> On 6/7/2026 9:44 PM, [email protected] wrote:
> > --disable-ai-traffic
>
> Thanks, that is what I was looking for. Any idea about the Livery issue?
>
>
> Wayne
>
>
>
> _______________________________________________
> Flightgear-devel mailing list
> [email protected]
>
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<div dir=3D"ltr">Isn&#39;t the transformation from one coordinate system to=
 another a task for the code that loads a model from a file?<div><br></div>=
</div><br><div class=3D"gmail_quote gmail_quote_container"><div dir=3D"ltr"=
 class=3D"gmail_attr">On Fri, Jul 10, 2026 at 2:41=E2=80=AFAM Josh Davidson=
 &lt;<a href=3D"mailto:[email protected]">joshdavidson2000@outlo=
ok.com</a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"m=
argin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left=
:1ex"><div class=3D"msg-8750960233946630352">




<div dir=3D"ltr">
<div style=3D"font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Cali=
bri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
Well, wiki also says:</div>
<dl style=3D"margin-top:0.2em;margin-bottom:0.5em"><dt style=3D"margin-bott=
om:0.1em">
<div style=3D"text-align:left;text-indent:0px;font-family:Aptos,Aptos_Embed=
dedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;col=
or:rgb(0,0,0)">
<b>Transform -&gt; +Y up</b></div>
</dt><dd style=3D"margin-right:0px;margin-bottom:0.1em;margin-left:1.6em">
<div style=3D"text-align:left;text-indent:0px;font-family:Aptos,Aptos_Embed=
dedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;col=
or:rgb(0,0,0)">
Make sure to keep this=C2=A0<b>OFF</b>. Blender uses a +Z up convention lik=
e FlightGear, so we do not adhere to the glTF standard (+Y up).</div>
</dd></dl>
<div style=3D"font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Cali=
bri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style=3D"font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Cali=
bri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
So does that mean glTF&#39;s will be +Z up?</div>
<div id=3D"m_-8750960233946630352Signature">
<div style=3D"font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Cali=
bri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style=3D"text-align:left;text-indent:0px;margin:0px;font-family:Aptos,=
Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-si=
ze:12pt;color:rgb(0,0,0)">
--</div>
<div style=3D"text-align:left;text-indent:0px;margin:0px;font-family:Aptos,=
Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-si=
ze:12pt;color:rgb(0,0,0)">
Josh Davidson</div>
</div>
<div id=3D"m_-8750960233946630352appendonsend"></div>
<hr style=3D"display:inline-block;width:98%">
<div id=3D"m_-8750960233946630352divRplyFwdMsg" dir=3D"ltr"><font face=3D"C=
alibri, sans-serif" style=3D"font-size:11pt" color=3D"#000000"><b>From:</b>=
 Josh Davidson &lt;<a href=3D"mailto:[email protected]" target=
=3D"_blank">[email protected]</a>&gt;<br>
<b>Sent:</b> Friday, July 10, 2026 01:32<br>
<b>To:</b> FlightGear developers discussions &lt;<a href=3D"mailto:flightge=
[email protected]" target=3D"_blank">[email protected]=
urceforge.net</a>&gt;<br>
<b>Subject:</b> Re: [Flightgear-devel] HDR / PBR / compositor info</font>
<div>=C2=A0</div>
</div>

<div dir=3D"ltr">
<div style=3D"font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Cali=
bri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
About next...</div>
<div style=3D"font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Cali=
bri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style=3D"font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Cali=
bri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<a href=3D"https://wiki.flightgear.org/Howto:Convert_from_AC3D_to_glTF" tar=
get=3D"_blank">https://wiki.flightgear.org/Howto:Convert_from_AC3D_to_glTF<=
/a></div>
<div style=3D"font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Cali=
bri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style=3D"font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Cali=
bri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
This doesn&#39;t make sense. In the AC3D system, Y is up/down, in FG Z is u=
p/down, in glTF, Y is up/down. Someone made a conscious choice to make Z up=
/down in FlightGear a VERY long time ago.</div>
<div style=3D"font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Cali=
bri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style=3D"font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Cali=
bri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
Can&#39;t that choice be duplicated so we don&#39;t end up with having to r=
ework 1000s of lines of code to move to glTF? Also wouldn&#39;t reworking i=
t mean coordinate schemes are now different for the model vs the FDE/etc? I=
f so, that would be horrible... but as would
 having to swap axis&#39; on the FDE&#39;s as that would ruin everything.</=
div>
<div style=3D"font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Cali=
bri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style=3D"font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Cali=
bri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
So emotional annoyance aside, wouldn&#39;t it be possible to simply swap -Y=
 and Z again on glTF just like is already done on AC3D? Reminder, in AC3D, =
Y is up/down... no idea why when blender got involved that changed to Z, or=
 why FG moved it to Z as well.</div>
<div style=3D"font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Cali=
bri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style=3D"font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Cali=
bri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
Basically, it would be so cool if we could reduce the amount of &quot;unnec=
essary breaking&quot; occurring in the glTF migration.</div>
<div style=3D"font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Cali=
bri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style=3D"font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Cali=
bri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
I would also like to ask why the emission animation was removed? What about=
 existing AC3D models? What if I need to make something light up conditiona=
lly? What do I do then?</div>
<div style=3D"font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Cali=
bri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style=3D"font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Cali=
bri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
In all honesty, I&#39;m really not thrilled about how much reworking I&#39;=
ll have to do when next releases if things continue this way...</div>
<div id=3D"m_-8750960233946630352x_Signature">
<div style=3D"font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Cali=
bri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style=3D"text-align:left;text-indent:0px;margin:0px;font-family:Aptos,=
Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-si=
ze:12pt;color:rgb(0,0,0)">
--</div>
<div style=3D"text-align:left;text-indent:0px;margin:0px;font-family:Aptos,=
Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-si=
ze:12pt;color:rgb(0,0,0)">
Josh Davidson</div>
</div>
<div id=3D"m_-8750960233946630352x_appendonsend"></div>
<hr style=3D"display:inline-block;width:98%">
<div id=3D"m_-8750960233946630352x_divRplyFwdMsg" dir=3D"ltr"><font face=3D=
"Calibri, sans-serif" color=3D"#000000" style=3D"font-size:11pt"><b>From:</=
b> Wayne Bragg &lt;<a href=3D"mailto:[email protected]" target=3D"_blank"=
>[email protected]</a>&gt;<br>
<b>Sent:</b> Sunday, June 7, 2026 23:18<br>
<b>To:</b> <a href=3D"mailto:[email protected]" target=
=3D"_blank">[email protected]</a> &lt;<a href=3D"mailt=
o:[email protected]" target=3D"_blank">flightgear-deve=
[email protected]</a>&gt;<br>
<b>Subject:</b> Re: [Flightgear-devel] HDR / PBR / compositor info</font>
<div>=C2=A0</div>
</div>
<div><font size=3D"2"><span style=3D"font-size:11pt">
<div>On 6/7/2026 9:44 PM, <a href=3D"mailto:[email protected]" target=3D"_=
blank">[email protected]</a> wrote:<br>
&gt; --disable-ai-traffic<br>
<br>
Thanks, that is what I was looking for. Any idea about the Livery issue?<br=
>
<br>
<br>
Wayne<br>
<br>
<br>
<br>
_______________________________________________<br>
Flightgear-devel mailing list<br>
<a href=3D"mailto:[email protected]" target=3D"_blank"=
>[email protected]</a><br>
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arget=3D"_blank">https://na01.safelinks.protection.outlook.com/?url=3Dhttps=
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ta=3D05%7C02%7C%7Cbbd40ada79cc460904d208dec5151e87%7C84df9e7fe9f640afb435aa=
aaaaaaaaaa%7C1%7C0%7C639164891710612798%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1=
hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ=
%3D%3D%7C0%7C%7C%7C&amp;sdata=3DhekN4nOxooY%2FMk3Tq1AZUxQz39SI1R1f%2BOgyoy8=
l938%3D&amp;reserved=3D0</a><br>
</div>
</span></font></div>
</div>
</div>

_______________________________________________<br>
Flightgear-devel mailing list<br>
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>[email protected]</a><br>
<a href=3D"https://lists.sourceforge.net/lists/listinfo/flightgear-devel" r=
el=3D"noreferrer" target=3D"_blank">https://lists.sourceforge.net/lists/lis=
tinfo/flightgear-devel</a><br>
</div></blockquote></div>

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