[x3d-public] Shader extensions and shadows in a ray / path tracing renderer.

[Michalis Kamburelis]

2017-04-12 19:29 GMT+02:00 Roy Walmsley <roy.walmsley at ntlworld.com>:
> One question I have just thought about relates to your proposed shader and
> shadow extensions. It is this:
>
>
>
> Currently your extensions are designed around an OpenGL rendering
> environment. X3D actually makes no assumptions about the rendering
> environment, so the standard should be equally applicable to, for example, a
> path or ray tracing renderer. Would your extensions still be valid in such
> environments?
>

The same question applies to the standard X3D "Programmable shaders"
component ( http://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components/shaders.html
), with the same answer:

1. On one hand, we try to make a specification incorporate various
possible shading languages - GLSL, HLSL, Cg.

  That's why we have the "language" field at the shader nodes.

  Also some shader languages require a little different organization
(e.g. for GLSL you use ComposedShader + ShaderPart. For HLSL, you use
ProgramShader + ShaderProgram). The specification encompasses them
all.

  My Effect extensions should also work with all shading languages. I
kept that in mind when designing them (see
https://castle-engine.sourceforge.io/compositing_shaders_doc/html/chapter.implementation.html
). If I failed, I'm sure it can be easily fixed, by drawing
inspiration from already-working standard "Programmable shaders"
component:)

2. We don't require the implementation to handle any particular
shading language. That's why "shaders" field is MFNode, so the browser
can choose any option it can. Or the browser can simply ignore the
"shaders" field, when none match (e.g. browser uses Direct3D (HLSL)
and user provides only GLSL shader code).

So, any renderer, real-time or not, could

- Make it's shading language (like RenderMan Shading Language,
https://en.wikipedia.org/wiki/RenderMan_Shading_Language ) available
through X3D shaders.

- Or just ignore the shaders, if not applicable.

Best regards,
Michalis