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Experts, we need your help. Draw Call Advice

Hi everyone,

We’re a fairly new team and building a VR game. We noticed something and are not sure how to fix it or handle it. If you are in one of our hallways and look to your right, there is a wall. You are totally enclosed in a hallway. When you look at the wall the draw calls are 1,200. Behind that wall to the right is a big open room with lots going on. If you are in the same hallway and look left at the other wall you see 240 or so draw calls. Behind that wall is pretty empty. Almost 800 draw call difference.

Please see image for a better explanation. How can we get draw calls down when looking at the right wall with a lot going on behind it?

Here is what we know.

  1. Occlusion culling is working fine. We use freezerendering and when you go behind that wall it is totally blank sky. everything is being occluded like it should.
  2. If you take the wall away, the draw calls are about 2K looking into the busy room. So it is not accounting for all the draw calls when the wall is up, just about 800 of them. Why?
  3. Can we use a volume or something to get rid of the draw calls behind the wall? It is killing frame rate in that hallway. If we can use a volume, which one and how exactly?
  4. Is it lightmaps going on in the main room? Nothing is leaking through. Very solid floor, wall, ceiling connections, 2 sided and thick, so there is no bleed.

Could someone explain why we are getting draw calls behind the one wall when occlusion culling is active? Does it have to account for what would be drawn behind that wall or something? How can we lower the draw calls when looking at the right wall?

Thanks in advance for the help.