Missing tiles in VR mode (regression w.r.t. Cesium 1.44)

[glathoud]

Hello, sometimes in VR mode some tiles are not displayed. From what I could see, the issue happens with Cesium 1.45 but not with Cesium 1.44.

To reproduce the issue:

• open the Sandcastle example "Ground Clamping"
• add the line vrButton: true to the Viewer config
• re-run the example, click on the VR button and move the camera around (see the screenshots below).

I also tried scene.logarithmicDepthBuffer = false but that did not change the behaviour.

Below, you can see the code, and screenshots taken with Cesium v1.44 and v1.45 at similar positions.
If I can do anything to further help, please let me know.

Screenshots

Code with vrButton: true:

---

Position 1, Cesium 1.44:

...vs Cesium 1.45:

---

Position 2, Cesium 1.44:

...vs Cesium 1.45:

[mramato]

This is most likely a dupe of #3812, which has been around for quite some time. It might have gotten worse in the latest release though (perhaps log Z related?) CC @bagnell

[glathoud]

Here is an example for a 1280x1024 screen device. Just click on the VR button and shortly after the camera will be moved to a problematic (position,direction) pair. Problem reproduced with a chromium browser under Lubuntu.

[glathoud]

Using that example the issue seems to appear in the master branch at the log depth merge 50b1d5d, and not on the previous commit 603640c

However in my tests, setting viewer.scene.logarithmicDepthBuffer = false; did not change the result.

[glathoud]

Here is a possible fix that makes the aspectRatio in configureCameraFrustum depend on useWebVR. In my tests it worked.

[glathoud]

Hello, it would be cool if someone could have a short look on the two small commits below and say whether they are worth submitting a PR.

• https://github.com/glathoud/cesium/commit/e85a779ff083f481aae74740295fb89a645b3b0f
• https://github.com/glathoud/cesium/commit/e47a7d5d57c78012f0607d12a95671ac5efa9ffb

[hpinkos]

Hi @glathoud! I'm not super familiar with this area of the code, but your fix make sense to me. It would be great if you can open a PR with that fix! Thanks!

[glathoud]

@hpinkos thanks for looking at the code. I just created the PR.