Re: Comments VRML 1.0 (Draft)

Robert Glidden (
Thu, 1 Dec 1994 16:05:05 -0800 (PST)

RE NURBS: How about limited nurbs support, for example optional support,
or a level of support. For example, only representations of Bezier piece-
wise cubic patches, which seem to be what most people want to use
surfaces for anyway. I think the concern for full blown nurbs support would
be that it would dramatically increase the difficulty of writing
browsers. A polygon-only browser ought to be relatively easy to write with
many of the polygon-based 3D APIs. Full blown nurbs scares people, but
bezier patches would probably be perceived by 3D API companies and
browser writers as a more manageable task.

On Thu, 1 Dec 1994, Jan Hardenbergh wrote:

> 1-DEC-94 jch - review of the VRML spec 1.0 (Draft) UNDATED!!!
> This stuff is better than virtual sex. (or maybe it will be virtual
> sex soon enough...)
> What follows are comments on the VRML 1.0 spec. The only really
> surprising thing is that only IndexedFaces made it as a surface.
> I think this is a mistake. I would add TriStrips, QuadMeshes and
> NURBSurfaces.
> Before the nits start, I want to say that this is a GREAT document for a
> first draft - some of that is due to the existing Inventor documents,
> but there is still a lot of new material here and it looks GREAT!
> Comments:
> Date the spec on each rev.!
> Be formal about what is really part of the specification and what
> is in the spec.
> The "mission statement" section should be labelled "Background"
> A mission statement might be:
> The mission of VRML is to become the standard interactive simulation
> language of the World Wide Web. This language will enable web surfers
> to perceive the Internet through the use of three dimensional graphics,
> animation, physics modeling to represent the web, other web surfers,
> documents and the world itself. VRML will enable a qualitative leap
> in our ability to understand and navigate through the web and its contents.
> -
> (BTW, modelling is English, modeling is American)
> noospheric - it ain't in my American Heritage, if you use it, define it.
> I think it is worth while to mention the other candidates (WebOOGL &)
> in the description of the selection process.
> Is the VRML (IFF) parser really available somewhere?
> The VRML 1.0 Requirements section seems very incomplete. The SIGGRAPH
> BOF notes have lots of things: ASCII, 3D Geometry, Hierarchy,
> Transformations, Material properties, textures, unit of measure,
> level of detail capabilities, URL "Anchorage", lights, camera, action...
> - Should require no new support from HTTP server. Just more files.
> Or do we expect all VRML to only come from VRML servers?
> Language Spec. This is the start of the real spec.
> I like Nodes!
> What is the scoping of names? Can a name be used outside of the
> curly braces (node) it was defined in?
> Please put a DEF in the example.
> Can I put children in any node? I.E. Sphere { radius 1 Seperator {...} }
> A quick test of OpenInventor does not like this.
> Do nodes always have names? If one is not specified, are they null?
> The vertical seam in a cone is in the YZ-plane in which the cone is
> defined, right? (Inventor calls this object coordinate space) or in the
> YZ plane after transformation (World coordinate space). Is anything
> ever defined in view or screen space? So, what...
> - please have a short section on spaces in the document (right hand)
> - we need to define the viewing & screen space in order to interact
> with the models. This is something that PEX/PHIGS did pretty well,
> tho, as usual it was overdone. We need it when we point at things
> and need to convert from window coords to world coords.
> (the notion of a digitize plane to which the pointer gets projected
> is useful for drawing)
> I guess I will just get used to points being a vector data type.
> For the cube, front is parallel with the XY plane, with positive Z?
> "the current cumulative transformation" includes the object to world
> and camera transformations? anything else?
> The structure of the document might be changed. I could not grasp the
> material binding stuff until I skipped ahead to the MaterialBinding
> node. I realize this is a second level of editing - better get the
> spec specified, then make it understandable...
> Light sources are affected by "the current transformation." Is that
> different from the "current cumulative transformation?"
> No TriangleStripSet, QuadMesh or NurbsSurface? Why not? The Inventor
> Mentor says on page 109 that triStrips and QuadMeshes are faster...
> If I were going to pick one primitive, it would be triStrip.
> NURBS are a trickier issue. However, since network bandwidth will
> be an issue, I think is is worth byting the bullet and putting NURBS
> in VRML.
> LevelOfDetail - GREAT!!!
> Where does the ambient light get specified? Don't we need an
> Environment? If the answer is that the environent is not part of VRML,
> then we need to supply an appendix that recommends what parameters
> should be controllable.
> Is the Ambient Color in the cycling example right? 0, 1, 1, 0??? (0,1,0,1)
> Good common metaphors for lights: Directional == sunlight, hits all objects
> from same direction at the same intensity, pointLight == naked light bulb,
> ans spot light is light a light bulb inside a coffee can.
> Does OpenInventor allow control over the attenuation of lights???
> Perhaps it is better not to allow control, since it just confuses
> most mortals. Anyway, please comment.
> As mentioned before, filename for the texture URL is confusing.
> Will their be rendering semantics specified? I.e., are OpenGL rendering
> semantics implied? Will people care? This is a tricky issue because soon
> enough there will be bugs saying (for example, ViewerXYZ point lights do
> not light anything more than 2 units away, but Labyrinth does it
> correctly) Will we be able to say what is correct?
> The other argument is that you limit the hacks you can do.
> Is there a default extension for textures?
> Is there a default checkerboard texture? (i.e. require viewers to
> find "checker.txr" locally.
> The VRML spec should specify the file format of textures.
> Good going on specifying the .wrl extension.
> Is anyone working on public domain servers & viewers? This stuff will
> catch on much more quickly if those are made available.
> A lurking question I have is the politics of choosing Inventor. I think
> it is a great choice technically - tho, I've never looked at WebOOGL.
> I've been impressed with Inventor since it came out. But, sometimes
> politics can be ...
> YON,, Jan C. Hardenbergh, Oki Advanced Products 508-460-8655
> =|= 100 Nickerson Rd. Marlborough, MA 01776
> Success is being happy with yourself even if today is your last but
> betting all your cyberbucks(TM) tomorrow will be better.