topic Re: Vive Tracker Matrix affected by HMD Position? in VRED Forum

Vive Tracker Matrix affected by HMD Position?

chaaseLTH9X — Thu, 17 Feb 2022 21:17:11 GMT

Hi all,

I'm trying to control the orientation of a texture on a material based on the angle of a Vive tracker. The script below works well for that, but there is an unexpected behavior. When I turn my head while wearing the HMD, the texture rotates, even if the Vive tracker is not moving. In the attachments, img1 is looking straight-on, and img2 is with the HMD turned to the right. Any ideas?

Thanks,

import math

tracker = vrDeviceService.getVRDevice('tracker-1')
tracker.enableRay('Z')

myDial = findNode('DialNode',True)
myMatl = myDial.getMaterial()
myTex = vrFieldAccess(myMatl.fields().getFieldContainer('colorComponentData'))
myComp = vrFieldAccess(myTex.getFieldContainer('diffuseComponent'))

def adjustDial():
myMatx = tracker.getTrackingMatrix()
rotXangle = math.atan2(-myMatx.row(1).z(), myMatx.row(2).z())
sinXangle = math.sin(rotXangle)
cosXangle = math.cos(rotXangle)
rotZangle = math.atan2(cosXangle * myMatx.row(1).x() + sinXangle * myMatx.row(2).x(), cosXangle * myMatx.row(1).y() + sinXangle * myMatx.row(2).y())
myComp.setReal32('rotate',math.degrees(rotZangle)+90)

tracker.signal().moved.connect(adjustDial)

Re: Vive Tracker Matrix affected by HMD Position?

CGBenner — Tue, 15 Mar 2022 14:45:42 GMT

@chaaseLTH9X

Hello! Do you still need assistance with this question?

Re: Vive Tracker Matrix affected by HMD Position?

chaaseLTH9X — Tue, 15 Mar 2022 15:02:43 GMT

Hi Chris,

Yes, I could still use some help!

Thanks,

Charles

Re: Vive Tracker Matrix affected by HMD Position?

CGBenner — Tue, 15 Mar 2022 15:10:53 GMT

@michael_nikelsky @Christian_Garimberti @seiferp

Gentlemen, do any of you have any thoughts on this question? Thank you all in advance (I know nothing about VRED!) 🙂

Re: Vive Tracker Matrix affected by HMD Position?

chaaseLTH9X — Fri, 08 Apr 2022 14:44:47 GMT

I stumbled on the solution when looking at another forum thread.

Changing:

myMatx = tracker.getTrackingMatrix()

to:

myMatx = tracker.getNode().getWorldTransform()

Does the trick. It turns out Vive pucks (and controllers, I think) have their tracking matrix tied to the HMD tracking matrix.