WorldViz User Forum - CAVE, navigation, tracked wand, coordinate systems

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- - CAVE, navigation, tracked wand, coordinate systems (https://forum.worldviz.com/showthread.php?t=2310)

CAVE, navigation, tracked wand, coordinate systems

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:

Code:

# 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:

Code:

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

Have you tried setting the cave origin as the parent of the wand object?

Code:

wandRender = viz.add('box.wrl',parent= caveorigin)

This should work as long as your wandtracker/viewtracker objects share the same coordinate system.

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).

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.

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.

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