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V3D some early impressions. [Was: Re: K3D some early impressions.]
Mark Collins wrote:
> And I just found another one...
OK - I've played with Vertex3D - here is my mini-review:
Vertex3D (V3D) is written with Game modelling (and specifically *OpenGL*
game modelling) firmly in mind. The data structure used within the modeller
and in it's file format is essentially just the OpenGL calls you'd use to
render the model. Hence it has no idea about model *structure* at all and operations
are linear in nature. When you create a polygon, you create a colour primitive,
a texture primitive and then a triangle primitive (ie a glColor, a glTexBind and
a glBegin...glEnd). If you need to insert a rotation into the model, you do
just that and you have to insert an 'unrotate' command after it...clearly
these translate into glPushMatrix/glRotate and glPopMatrix respectively.
The order of primitives in the modeller is therefore critical - move
a part of the model up or down the list and the textures, colours, etc
of everything after it will change. Dunno about you - but I use
more sophisticated 'state management' in my applications...I expect
yet better of my modeller - I don't want to do all that stuff by
This aparrent simplicity makes it VERY difficult to model anything
substantial. There appears to be no mechanism to allow you to grab
more than one vertex at a time and drag them around the screen. There
is no way to snap vertices together - that kind of thing. There are also
no higher level primitives than the ones that OpenGL provides - hence
no spheres, cubes, cylinders, etc, no 'extrude', no 'surface of revolution'.
V3D also makes heavy use of the middle mouse button - which is not a
good idea in a world where two button mice are so common. Doing the
"both-buttons-at-once" trick to get to the middle button doesn't work
well with GTK applications because it doesn't allow enough time to
elapse after seeing a single-button click to allow the second button
to go down.
V3D currently only imports and exports its own native file format (.v3d)
which is a fairly simple ASCII setup. There is even a library provided to
read and write '.v3d' files. There is a 'DXF' plugin - but it didn't
seem functional when I tried it.
The total lack of a hierarchical scene graph (or polygon grouping of
any kind) will make it impossible to import models from other
formats, modify them in some small way and write them out again.
Since V3D allows 'plugins' it would be possible to rectify some of these
problems - but there seems to be a long way to go before you could call
this tool 'useful'. The tool seems stable - although a couple of people
I've spoken to said it crashed a lot - I didn't see a single failure.
There is no scripting language (although I suppose you could hack together
a plugin that added Python scripting pretty easily).
The 'undo' feature is rather limited.
The GUI presents a lot of "Do you really want to do this" type boxes - each
with FIVE options ("Yes", "Yes to All", "No", "Cancel", "Help") - this can
get very tedious very quickly.
On the plus side, you can tweak texture coordinates and colours on a vertex
by vertex basis - not many modellers (and *none* under Linux AFAIK) let you
V3D is released with full source under GPL - it runs under Linux and
(with a bit of prodding) has been made to work under Windoze (it uses GTK
which makes Windoze ports problematic).
I guess you *could* use V3D for very low polygon count models - but I'd
hate to have to build even a 100 polygon model with it as it is now.
----------------------------- Steve Baker -------------------------------
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