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

Cedric Neukirchen
Fri, 26 Aug 2016 14:50:13 +0000
XR Development

Hey there,

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

REPRO STEPS

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 (!), the Debug stuff moves and rotates

This is clearly visible on the Computer Screen! In the 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.

WHAT SHOULD HAPPEN?

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.

WHAT HAPPENS INSTEAD?

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

ADDITIONAL INFORMATION

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.

VIDEO REFERENCE

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

https://dl.dropboxusercontent.com/s/q9hcvu3o4i5ksg6/terad.mp4

Any more information? Just ask me (:

5 posts - 4 participants