[x3d-public] Basic Shaders

[John Carlson]

I don't know as the shader should follow the X3DOM/x_ite path or the BS
contact path.   Certainly BS Contact looks a bit better.

John

On Tue, May 22, 2018, 1:54 PM Andreas Plesch <andreasplesch at gmail.com>
wrote:

> It looks like the simpleShader scene was just updated to use light
> direction rather than light location:
>
>
> http://www.web3d.org/x3d/content/examples/Basic/Shaders/SimpleShaderIndex.html
> (The CDATA does not show but should in the xml:
>
> http://www.web3d.org/x3d/content/examples/Basic/Shaders/SimpleShaderCanonical.xml
> )
>
> So I updated the x3dom port accordingly:
>
> https://rawgit.com/andreasplesch/x3dom/inlineShader/test/regression-suite/test/cases/composedShader/inlineShader.xhtml
>
> It is more sensible to use direction since the headlight is a directional
> light.
>
> In x3dom it was necessary to invert the light direction, and the
> center ring is broader.
>
> BTW: x_cite produces this helpful warning on
>
> http://www.web3d.org/x3d/content/examples/Basic/Shaders/SimpleShaderIndex.html
> :
>
> x_ite.min.js:15 ComposedShader Cobweb Using uniform location name
> »x3d_LightDirection[0]« is depreciated. See
> http://create3000.de/x_ite/custom-shaders/.
>
> One is supposed to use vec3(x3d_LightSource[0].direction) where
> uniform x3d_LightSourceParameters x3d_LightSource[8] .
> as in:
> vec3 light_dir = x3d_LightSource[0].direction;
> intensity = dot (-light_dir, n);
> Hm, I just found that with the new uniform, it is also necessary to
> invert the direction in x_ite.
>
> -Andreas
>
> On Tue, May 22, 2018 at 12:57 PM, Andreas Plesch
> <andreasplesch at gmail.com> wrote:
> >> 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
>
>
>
> --
> Andreas Plesch
> Waltham, MA 02453
>
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