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  #1  
Old 03-19-2011, 02:07 PM
Salvar Salvar is offline
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How can I link MainView with HMD and a 3d node?

Hi all,

I've hit a technical snag in the research project I'm currently working on.

I have a virtual environment, containing a 3d node (car). The car is controlled by a custom action class I wrote for it.

To keep the viewpoint in tandem with the car, I have viz.MainView linked with the car. Everything works well and good. I move the car, mainview moves with it.

Now, I want to add HMD head-tracking into the mix. And that seems to be tricky. If I link the mainview with the HMD tracker after linking to the car, the car link breaks and it doesn't move with the car anymore. And vice versa.

How can I get these two things to work together?
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  #2  
Old 03-21-2011, 10:23 AM
farshizzo farshizzo is offline
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Is the tracker on the HMD 6DOF or 3DOF orientation? Either way, to integrate HMD tracking you should just need to use the <link>.preMultLinkable command. After you have setup the link between the car and the viewpoint, just add the following code:
Code:
view_link.preMultLinkable(tracker)
The HMD tracker data should now be applied relative to the car orientation.
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  #3  
Old 03-22-2011, 01:13 PM
Salvar Salvar is offline
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Quote:
Originally Posted by farshizzo View Post
Is the tracker on the HMD 6DOF or 3DOF orientation? Either way, to integrate HMD tracking you should just need to use the <link>.preMultLinkable command. After you have setup the link between the car and the viewpoint, just add the following code:
Code:
view_link.preMultLinkable(tracker)
The HMD tracker data should now be applied relative to the car orientation.
Thanks for the response.

I was hoping for the solution to be something simple as this, but it gives me an error saying that the tracker object (added with the command "polhemus = viz.add('polhemus.dle')") is not a linkable.

Is there any way to make it linkable?
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  #4  
Old 03-22-2011, 01:20 PM
farshizzo farshizzo is offline
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That is because the polhemus object is not linkable, it is an extension. Have a look at the documentation for the polhemus plugin on how to connect to a polhemus tracker. You never mentioned which tracker you are using, but the documentation page should describe how to connect to all supported polhemus trackers.
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  #5  
Old 03-22-2011, 01:31 PM
Salvar Salvar is offline
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Oh, wait. I was trying to link to the extension, not the liberty tracker itself. Awkward.

I don't have access to the tracker to test this now, but it runs without the linking error now. Here's hoping.

Thanks for the help.
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  #6  
Old 03-22-2011, 09:14 PM
Salvar Salvar is offline
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Just to close this thread, I tried the preMultLinkable call you suggested and it worked perfectly. I had to apply a preEuler command to the link first, but after that it was gravy.

Thanks!
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