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[VR] Drawn Debug shapes are offset, doubled and moving when moving HMD

Hey there,

so I downloaded the latest 4.13 Preview, which is currently Preview 3.


  1. Use 4.13 Preview 3 (can also happen in 4.12 etc, but I found it in 4.13 P3

  2. Create a new Project and use the "Virtual Reality" Template (can also happen in other templates, not tested)

  3. After you created the Project, open the "MotionControllerMap"

  4. Now, locate the "BP_MotionController" Blueprint and open it

  5. In there, locate the "TraceTeleportDestination" function and open it

  6. In here, you will see a big node called "Predict Projectile Path"

  7. Extend the Node and select a Draw Debug Type. I used "For Duration"

  8. Now start the Game in VR and activate the Teleport Process, by pressing the Touchpad UP on one of your MotionControllers

  9. Do NOT release it! Notice how it's offset to the actual Cyan colored spline.

  10. Also notice, that if you keep the Controller fixed at one point and rotate the HMD (Vive!), the Debug stuff moves and rotates

This is clearly visible on the Computer Screen! In the Vive HMD itself (When wearing it), you will see the following:

Left eye sees only one offset Debug to the right of the spline and right eye will see one that fits the Spline and a SECOND one that is offset to the left.


The Debug should cover the same path as the cyan colored Spline, as the "Vector Array", which the Node returns, is used for these. Also the Debug shouldn't move when you rotate your HMD. And the Debug Drawing shouldn't be duplicated.


Debug is offset to the right/left (depending on eye). Debug moves when rotating the HMD. One display of the Vive HMD (right eye) sees two traces where one actually is correct!


Instead of turning on the Draw Debug Type, you can also use a For Each Loop on the Vector Array and use "Draw Debug Sphere" with each point of the Array. The result will be the same.

My guess is, that this happens for all Debug renderings here. The Predict Projectile Path just happens to show the problem.


This is only showing the view from the screen of my PC. For Vive HMD you will need to test it yourself.


Any more information? Just ask me (:

Product Version: UE 4.13 Preview
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asked Aug 26 '16 at 02:50 PM in Bug Reports

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Hello eXi,

After reading over you post, it appears that this is a known issue. I have provided a link to the public tracker. I believe the issue mentioned is covered under this report. Thank you for the additional information.

Link: https://issues.unrealengine.com/issue/UE-34600

Make it a great day

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answered Aug 26 '16 at 05:27 PM

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Rudy Q ♦♦ STAFF
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avatar image eXi Aug 26 '16 at 05:30 PM

Hey Rudy,

Thanks for the heads up, but the post you linked talks about line traces. Also it mentions that the debug only appears in one eye.

So the issue is maybe related but not at all the same.

(: cheers!

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I have the same issue. It is caused by having Instanced Stereo turned on in the Rendering settings.

Turning it off fixes the problem, obviously at the cost of not having the instanced stereo speed boost.

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answered Sep 01 '16 at 07:29 AM

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