This reply is a place for FAQs with VAT3.0 in Unreal Engine 4 and 5. It will be kept up-to-date.Q: My VAT in UE looks broken. What do I do?
Most often, the issues with VAT in UE4/5 (more on UE5 in the next question) can be resolved (or at least tracked down) by one of the following steps. If none of the steps identifies or fixes the problem, please don't hesitate to reach out to us at firstname.lastname@example.org
and submit it as a "question". We typically respond within a day or two to questions.Q: Why is my VAT mesh full of holes in UE5?
UE5 changed some mesh UV implementations which can cause VAT mesh to look glitched. It happens often with the Dynamic Remeshing (Fluid) mode. To address this issue, you can simply go to UE5 Mesh Editor and turn on UE4 Compatible UVs. If that does not work even after you restart UE, try turning off UE4 Compatible UVs and turning on Use Full Precision UVs (which is somewhat more expensive, only use if absolutely necessary).Q: Why does my fluid sim via Dynamic Remeshing mode have flickering normals?
This is due to the changing topology of the geometry that is remeshed every frame. This problem may be more noticeable when the poly count is low and when surface has many rapidly changing details. You can help alleviate this issue by redistributing more poly count to the player-facing areas of your animation by adding a retention attribute when you poly reduce.
I will be working on a more permanent solution to spatially and temporally stabilize the normals for this kind of animations. The solution will probably be released as a standalone SOP that stabilizes your geometry before it is sent to VAT ROP.