CAVE, navigation, tracked wand, coordinate systems

[JimC]

I have Vizard running on two walls of a CAVE. Head-tracking is working perfectly, and I can use a tracked wand to point and fly around. Here's a code fragment to indicate what I've done so far:


# SyzygyTracker subclasses viz.VizNode+viz.EventClass
viewtracker = SyzygyTracker( service, matrixIndex=0 )
# Ditto for SyzygyNagivator
navTracker = SyzygyNagivator( service, matrixIndex=1, xIndex=0, zIndex=1, speed=1. )
# Create and configure a Cave object
cave = vizcave.Cave()
makeCAVE( cave )

# Attach the head tracker
cave.setTracker( pos=viewtracker, ori=viewtracker )

# Attach the navigation (wand) tracker.
caveorigin = vizcave.CaveView( viewtracker )
navLink = viz.link( navTracker, caveorigin )


I want to have a virtual object attached to the wand. I defined another tracker object tied to the wand and tried the following:


wandTracker = SyzygyTracker( service, matrixIndex=1 )
wandRender = viz.add('box.wrl')
wandRender.setScale( .02, .02, 2. )
wandLink = viz.link( wandTracker, wandRender )


...which initially works great, I end up with a virtual rod attached to the wand. However, its position is being set in world coordinates, so as soon as I start flying around it gets left behind. I've tried setting various Src and Dest flags on the link, or add()ing it to the caveorigin, but I don't really understand what I'm doing and the things I've tried so far haven't worked. What's the right way to do this?

Thanks,
-Jim

[farshizzo]

Have you tried setting the cave origin as the parent of the wand object?wandRender = viz.add('box.wrl',parent= caveorigin)This should work as long as your wandtracker/viewtracker objects share the same coordinate system.

[JimC]

Not quite, I'm afraid. That is, it may be mathematically correct, but when I set parent=caveorigin, the node's drawImplementation() never gets called (determined by substituting a Python custom node for the Box.wrl).

[farshizzo]

What version of Vizard are you running? In older versions, nodes parented to CaveOrigin objects would not be rendered, but this should be fixed in newer versions.

[JimC]

3.13.0002. Too old?

[farshizzo]

I believe the fix appeared in version 3.14, so you are one version too old. We just released 3.15 last week. Click on Help -> Check for updates in the Vizard menu and it should take you to a download link for the latest version.

[JimC]

Thanks, it's working now. So is wand-based picking, though it took me about an hour to realize that viz.intersect() was always returning the virtual rod that I'd just attached to the wand... :D