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RE: [x3d-public] Shaders and Triangles: was dedicated working-group focus on X3D interoperability
Hi, Dave --
What is missing is tutorial material that explains things in "content
author"-speak. Fortunately, this is about to change. The new Daly and
Brutzman book will be out in about another month.
-- Dick
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> -----Original Message-----
> From: owner-x3d-public@web3d.org
> [mailto:owner-x3d-public@web3d.org] On Behalf Of Dave A
> Sent: Wednesday, December 20, 2006 4:10 PM
> To: Holger Grahn
> Cc: John A. Stewart; X3D Graphics public mailing list; Web3D
> Consortium Members
> Subject: Re: [x3d-public] Shaders and Triangles: was
> dedicated working-group focus on X3D interoperability
>
> With this and other threads going around, it seems to me that
> the question being asked is: for whom should X3D be easy for:
> browser/plugin programmers, or content authors. My vote:
> content authors. Unfortunately, the spec has largely been
> driven by browser programmers. This IMHO is why X3D has been
> problematic.
>
> Dave a
>
> Holger Grahn wrote:
> >
> > Hi John
> >
> > Regarding the Triangle nodes I agree that X3D has sometimes
> a bit of a
> > node bloat philosophy.
> >
> > The IndexedFaceSet could represent handle it all.
> >
> > On the other hand IFS in its generic form with per face attributes,
> > creaseAngle and seperate index list into attributes array
> doesn't fit
> > the Open GL or Directx layout.
> > To render an IFS, one need to reformat/copy the data to flattened
> > array structures.
> >
> > The Triangle Set nodes are more constrained, they are
> fitting better
> > direct the OpenGL geometry mapping.
> > But for DirectX9 requireing the interleaving of all
> attributes of a
> > vertex into one structure, they don't help much.
> >
> > Hardware Shaders so far operate indepentently on vertices
> and pixel /
> > fragments, they can work on all primitives, I don't see
> Justins point
> > here, beside there might be differences how implementations compute
> > normals etc.
> >
> > This changes with DirectX 10 adding geometry shader
> capability where
> > the actual input triangle structure is important.
> > Unfortunately in DirectX10 you always need to implement all
> appearance
> > using a shader, so the classical OpenGL
> > lighting/material/texture/multitexture/fog
> > model has been completly removed.
> >
> > Greetings
> >
> > Holger
> >
> >
> >
> >
> >
> > ----- Original Message -----
> >
> > *From:* John A. Stewart <mailto:alex.stewart@crc.ca>
> > *To:* Justin Couch <mailto:justin@vlc.com.au>
> > *Cc:* X3D Graphics public mailing list
> <mailto:x3d-public@web3d.org>
> > ; Web3D Consortium Members <mailto:consortium@web3d.org>
> > *Sent:* Wednesday, December 20, 2006 9:10 PM
> > *Subject:* [x3d-public] Shaders and Triangles: was dedicated
> > working-group focus on X3D interoperability
> >
> > Justin;
> >
> > Throwing in some more canadian pennies in the bowl;
> >
> >> I'll go one step further. It's impossible to use
> Shaders without
> >> the Triangle* nodes. Shaders require direct knowledge
> of the exact
> >> geometry structure coming at them as well as precise
> control over
> >> every aspect of the incoming geometry in order to
> work. Remove the
> >> Triangle nodes and you must also remove Shaders too as they're
> >> pointless without them.
> >
> > We still don't need the *Triangle nodes for shaders. What the
> > browser would
> > need to recognize in your example, is that it should
> *not* optimize,
> > and feed
> > the triangles as encountered. *that* mapping can be
> specified, and
> > the browser
> > certainly would know if a Shader was present, or not.
> >
> > While shaders are certainly cool, and my GPUGems books
> reside within an
> > elbows reach of me, I doubt whether many on this list
> would choose
> > to, um,
> > teach shader programming in high school, for instance.
> >
> > Shaders are neat, and have their place, but, at the
> moment, their
> > application
> > is rather specialized.
> >
> >
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