VRChat Upgrade to Unity 2017.4

If you’re a VRChat Creator, you’re probably familiar with the fact that VRChat currently runs on Unity 5.6.3p1. This has been the case since August of 2017, when we upgraded from Unity 5.3. We would like to announce that VRChat is planning to upgrade to Unity 2017.4.15f1 LTS for an upcoming release within the next couple of weeks. We have a special Open Beta available to all users that can be used to test the new version, as well as upload content. A common question we’re expecting is “Why not Unity 2018?” We’re primarily focused on moving to Unity LTS (Long-Term Support) versions rather than every incremental Unity version. This allows us to ensure that we’ll receive support from Unity in the long-term and that future upgrades go more smoothly. Once 2018 has an LTS version released, we can start looking into moving forward with that upgrade. We chose Unity 2017.4 LTS because it gets us a lot of fixes, tools, and improvements that have come along with the last year of Unity development. It also allows us to easily upgrade to further Unity LTS versions once they become available. Finally, Unity’s LTS branches ensure that we have support and compatibility for quite some time thanks to the extended support cycle. As stated above, the upgrade carries with it all of the improvements, fixes, and changes that Unity 2017 included. There’s a lot to see! Here’s some of the more interesting bits: ● Fixes for Audio/Video sync on Unity Video components (and therefore VRC_SyncVideoPlayer) ● Support for Unity Store Assets that require 2017.4 ● Much easier version upgrade workflow when the next Unity LTS releases If you’re interested in checking out some of the more detailed additions, we’ve whipped up this document for you.

Upgrading Content

Technically speaking, Unity upgrades often change the way that the shader and rendering pipeline work, which break shaders on content. When we performed our 5.3 to 5.6 upgrade, our community was significantly smaller and asking users to re-upload all of their content was not as scary of an ask. VRChat’s Community is now much larger, and asking users to re-upload all of their content is simply not viable. With some very gracious assistance from Unity, we have managed to avoid this issue and move forward with VRChat. Unity provided us with a patch was released in 2017.4.15f1 LTS that allows us to use the shaders included with the AssetBundles you’re uploading to VRChat.

Getting Ahead of the Curve

Even with a careful upgrade process and working with the Unity team, upgrading a large amount of user-generated content is no small feat. There are some things to be aware of that will affect most Community content. The good news is that for these items, a simple re-upload using Unity 2017.4 will fix your issues. You will want to re-upload your content using 2017.4.15f1 LTS during the Open Beta if:

• You have mirrors in your world. If you have a mirror in your world in 5.6, the mirror will not display properly in 2017.4. The rest of the world will be fine, but the mirror will be broken.

• You have baked lighting and you still have the Baked Lights enabled in the scene. Those lights will be set to Mixed when viewed in the 2017.4 client, resulting in the scene having both Baked and Realtime lighting, significantly reducing performance. Re-uploading the world in 2017.4 will fix this issue.

• You use Real-time GI (Global Illumination) in your world. If you use a