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constraints

DOCUMENTATION MOVED

Go to the new version of this page at https://docs.gmetri.com/guidelines-compatibility/guidelines/experience-optimizations

Constraints

There are certain limitation you should keep in mind while building a GMetri experience.

2D elements won't work in VR mode​

If you are building primarily for a headset, then avoid using 2D HTML eleemnts like Actionbar, Quiz etc.

Max Pano resolution should be capped at 4K for low-end devices​

This also includes the Oculus Go. Go through asset recommendations to get an idea of recommended asset resolution and size. This needs to be verified while uploading the assets. You can find the size and resolution of assets on the right pane of the File Manager.

Depth comes into play with VR mode​

Placement of graphics is very important here. Things look very different in 2D and 3D.

Graphic memory is limited on any device​

Graphic memory gets used by Videos and Images. Anything you see on the screen is first expanded a bitmap image (a simple pixel by pixel representation of an image using 0's and 1's) onto the system's graphic memory - be it your laptop, phone, headset or any other device.

Lets say you have a videos of resolution 1000px x 1000px running parallely, for every single frame you end up using 1000x1000 x (4 bytes per pixel) = 4MB of video memory.

note

On most modern phones and laptops, the available graphic memory varies from 256 MB to 4 GB. However, Chrome limits the amount of graphic memory available to a single tab to a small fraction of this - between 128 MB and 256 MB.

This is important, as its very easy to balloon up your graphic memory usage, and end up in a hung state. For example, if you run 3 4K (4096x2048) vidoes, you are effectively using 3x4096x2048 x (4 bytes per pixel) = 48MB of memory for every single frame!

So, try to limit the number of high resolution images and videos you add to a scene.

When you run out of graphic memory, you may also see things like green screen not work properly.

Audio limitations​

There is a hard limit on the number of Audio elements (including both Audio and TTS elements) that can be added in a single scene. Currently, this limit is set to 60 to ensure that there are no overloading issues when the experience is played on low-end devices.

There are 2 approaches to moving around this restriction:

  1. Re-use the same audio element to play different parts of the audio at different instances using the "play from" event.
  2. Break down the scenes such that the total number of Audio elements doesn't go beyond 60.

Audio on iOS Devices​

iOS devices don't support volume controls. This has two implications:

  1. No volume control icon on top of the experience
  2. Volume control rules don't work