[x3d-public] Basic Shaders

[Andreas Plesch]

> Date: Tue, 22 May 2018 00:52:54 -0400
> From: John Carlson <yottzumm at gmail.com>
> To: Don Brutzman <brutzman at nps.edu>,  X3D Graphics public mailing list
>         <x3d-public at web3d.org>
> Subject: [x3d-public] CDATA sections don't show up on this X3D
>         Resources Example, Basic Shaders, that  I can see in the decorated X3D
> Message-ID: <5b03a226.1c69fb81.c965e.d3da at mx.google.com>
> Content-Type: text/plain; charset="utf-8"
>
> I haven?t tried copy/paste.
>
> http://www.web3d.org/x3d/content/examples/Basic/Shaders/SimpleShaderIndex.html
>
> This is on the web page itself.
>
> Also X_ITE is drastically different from something like BS Contact for example.
>
> We need more ports. FreeWRL? X3DOM (maybe put a switch in for the Proto?).

Here is John's port to x3dom:
https://rawgit.com/andreasplesch/x3dom/inlineShader/test/regression-suite/test/cases/composedShader/inlineShader.xhtml
. It is a literal port and it is unclear if it results in the expected
rendering.

I believe the main difference between browsers is in the naming of the
uniforms supplied to the shader code. I think there was a discussion
on the list about these naming conventions.

Another source of incompatibility in shaders is the choice of shading
language. Even within the glsl language, probably the dominant
language, there are different versions.

A large step towards compatibility would therefore be requiring the
restricted subset of glsl GLSL ES v3 (for composed custom shaders) as
the single glsl version:

https://www.khronos.org/registry/OpenGL/specs/es/3.0/GLSL_ES_Specification_3.00.pdf

This had the additional benefit that shaders would be largely
compatible with webgl2.

Another potential source of incompatibility in the example is in the
definition of what data uniforms should supply, independent from the
naming. It looks like some browsers may supply the direction and
location of lights in object space, others in eye space (already
transformed by the view matrix). Eye space seems to be what gl
traditionally supplies for lights.

-Andreas