RE: late draft of the 1.0 Clarifications

Steve Ghee (steve@division.co.uk)
Thu, 23 Nov 1995 15:30:09 -0000


<http://www.oki.com/vrml/vrml10c.html>

There are some points in this document that do still need clarification =
:-

1) IndexedFaceSets (etc.)

Should the materialIndex, normalIndex and textureCoordIndex definitions =
include a -1 to indicate the end end of a polygon? I would say they =
should, as this would at least make the various field specifications =
consistent. It is sort of implied inthe document, but should be =
explicitly stated in the node definition.

e.g.=20
IndexedFaceSet {
coordIndex [ 0, 1, 2, 3, -1,=20
4, 5, 6, 7 -1 ]
normalIndex [ 0, 1, 2, 3, -1,
4, 5, 6, 7, -1 ]
}

An example showing these would also be useful - the only IndexedFaceSet =
example is towards the end of the document, and it only includes a =
coordIndex definition.=20

I have also ssen .wrl examples where Normals and TextureCoordinate2 =
nodes are defined but the IndexedFaceSet omits the normalIndex and =
textureCoordIndex fields - the implication is the normal and texture =
coordinates are indexed using the coordIndex field; if this is so, the =
spec. should make this clear. =20

2) FontStyle

Should the default size value be 10 ? - the spec. says this is in object =
space units (i.e meters) - a default character sst 10m high seems a bit =
strange to me, particularly when all other standard shapes (cubes etc.) =
have default fields of 1 unit (i.e. 1 meter)

3) AsciiText

Does the width field refer to character width, or rendered width (i.e. =
in object space units)? i.e. if I specify

AsciiText {
string "hello there"
width 5
}

should this display "hello" (i.e. 5 characters), squash the entire =
string to be 5m wide, or display as much of the string that will fit in =
5m spacing depending on the FontStyle.width sstting?

The following are perhaps more VRML1.1 issues (esading Bernie Roehl's =
"VRML1.1 Changes" document), but it may be worth clarifying some of =
these issues inthe VRML1.0 spec to prevent incompatible worlds being =
cesated in the meantime

4) LOD node

I believe the LOD should be a Separator, i.e. no state can leak out and =
affect state below it in the scene graph. This should be stated now! =20

5) Switch

I thought the Switch node was to become a Separator? i.e. no state =
leaks out. The spec. should state this, and reference to Switch (-3) =
being the same as a Group should also be removed; Groups are being =
depreciated.

Also, the -3 state was to be dropped (i.e. you cannot activate all =
children within a Switch). Again, it's use should be discouraged.

------------------------------------
Steve Ghee email: steve@division.co.uk
Director of New Technolgy www: http://www.division.com
Division Ltd tel: [+44] 145 461 5554
19 Apex Court fax: {+44] 145 561 5532
Woodlands
Almondsbury
Bristol BS12 4JT
UK.


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