From: Dahlia Trimble<dahliatrim...@gmail.com>
Subject: Re: [Opensim-dev] How does PBR material scale/rotation/offset
reach the viewer?
It's been nearly a decade since I worked on the materials implementation
for OpenSimulator, and it's possible that my memory may be inaccurate or
things have changed since I left the project.
i seem to remember that materials will default to the same texture
transform parameters for the prim or mesh face that they are applied to as
the texture for that face, unless they are overridden by the materials
editor in the viewer. Therefore if you don't see them in any materials
LLSD, use the texture parameters. This should be true for materials such as
specular and normal maps. I haven't seen PBR but I would assume a similar
approach were used but knowing LL, this may not be the case.
I'm not aware of any glTF implementation in OpenSimulator; if there is one
it must have been added after I left.
Yes, it's all new. Second Life added it to their system and Ubit is
putting it into Open Simulator. It works roughly as follows:
There's a new PBR Material asset, which is LSL wrapped around a glTF
material. The glTF material follows the glTF 2.0 spec. There are
BaseColor, Normal, RoughnessMetallic, and Emissive layers,
Where the glTF spec calls for a filename, there's a UUID.
The glTF material info does not have scale/rotation/translation
info. PBR Material assets are first class assets - you can
name them, put them in inventory, sell them, etc.
The PBR Material UUID is in a new "Extra Parameter" associated with
the ObjectUpdate UUID message. That just has an array of
(face number, UUID), with no scale/rotation/translation.
If an object has a PBR Material associated with it, all the old
color and texture info is overridden. It's not gone; if you remove
the PBR Material link from the object, the old color and texture
reappears.
Each PBR layer has its own scale/rotation/translation, which
appear to be totally separate from the ones used for the old content.
I can't find where those are sent to the viewer. That's the problem.
John Nagle
Animats
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