Larry Ramey (ramey++at++ccpo.odu.edu)
Tue, 12 Jan 1999 13:09:25 -0500
pfPeople->PutOnThinkingCaps(pfPeople->getListOfSmartPeople());
I have a design issue for the older and wiser heads amoung you. We are
designing a Virtual Enviroment (CAVEApp) that has potentially many
coordinate systems. These CoordDefs store a matirix that position the
local coords in Graphic space. Graphical objects come in in Data units
and are translated to Coord Space. They are drawn in local Coord space.
It is quite a good solution for us, simply multipy every local Coord
vert by the CoordDef matrix to obtain the Graphic space vert.
In OpenGL we simply multiplied the ModelView matrix by the
CoordDef->matrix. In Performer we need to put a DCS above all the
graphic objects created from a specific Coord.
There is a One to One coorespondence between Coords and DCS that make
this an easy solution. The problem is interactively moveing a Coord
around in Graphic space. These demands selecting the DCS and
recalculateing the DCS matrix based on wand input... not a problem. IT
ALSO MEANS UPDATEING THE COORD OBJECT THAT CORESPONDS TO THE DCS. This
is not such a big problem, we can specify a callback when the DCS is
created. But what about if I bring a widget up on the screen and type in
a new position for the CoordDef in the Graphic space? The CoordDef then
needs to update the DCS. This demands that my CoordDef contain performer
code... kinda sucks, but I can get over that... we can isolate it with
#define USEING_PF.
My question is (you were wondering when I would get to it wearn't you?)
is:
Isn't this sort of coupleing exactly what FCS,and pfEngines were
designed for?
If I should use a FCS could someone give a a nudge in the right
direction...
All I really need is some psuedoCode showing who is responsible for
doing what. I figure I could kludge something together that would work,
in fact I am doing that right now... but I would like to know the
"proper" way to do this.
larry->thanks();
--Larry E. Ramey ramey++at++ccpo.odu.edu
"Misery can be a heavy load" -Social Distortion
"All science is either physics or stamp collecting" - Rutherford
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