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Issue metadata

Status: Available
Owner: ----
Components:
EstimatedDays: ----
NextAction: ----
OS: Android
Pri: 2
Type: Task
Proj-XR
Proj-XR-VR

Blocking:
issue 837646



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Investigate shader swap time and prototype improvements

Project Member Reported by cjgrant@chromium.org, May 15 2018

Issue description

We should reverse the eye/element nesting order, to cut the number of shader changes in half.  Brandon has indicated that shader changes are much more heavy than viewport bounds changes.

If that shows a meaningful perf increase, then we should also try combining our texture and gradient shaders to eliminate 90% of our swaps.
 
Components: UI>Browser>VR
Owner: cjgrant@chromium.org
Status: Assigned (was: Available)
Labels: -Type-Bug Type-Task
Owner: ----
Status: Available (was: Assigned)
I did a prototype of this, but didn't see a significant gain.

On a Pixel 2, the change traces (over a 10 second average) as:

Without:  4.15 ms
With:     3.96 ms

The downside is a bit of extra complexity.  The prototype code is here if we want to pursue this:

https://chromium-review.googlesource.com/c/chromium/src/+/1071716
If we are doing draw calls for both eyes, we may be able to quickly try out multiview.

https://www.khronos.org/registry/OpenGL/extensions/OVR/OVR_multiview.txt

This could reduce draw call count by half.

Comment 4 by ddorwin@chromium.org, Jan 18 (4 days ago)

Labels: OS-Android

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