Migrating to Unreal Engine 5: Lumen, BSP and more

Aug 03, 2022 at 02:18 pm by nemirc

Migrating to Unreal Engine 5: Lumen, BSP and more
Migrating to Unreal Engine 5: Lumen, BSP and more

Hello again and welcome my UE5 series. After testing various things, I decided to just make the move to UE5, but only for Just Let Me Go. The other UE project, Killer Dolls, is still going to be a UE4 game.

The reason I decided to completely do the transition is Lumen. On one side, Lumen can create all those nice real-time GI effects, and JLMG could really benefit from that. However, the thing that made me make the move was the fact that in UE4, when using “stationary” lighting (which combines baked lighting and real-time lighting), you can only have a limited number of lights hitting a point, and overlapping lights produce errors (as seen by the red X on the light in the image below). Since I am still figuring out the way the house will be lit, so I had a lot of overlapping lights to lit the entire house. This wouldn’t be an issue if JLMG was using baked lighting for the environment, but that’s not the case since there’s a mechanic that allows you to turn on/off lights.

I’ve been building the house using Unreal’s BSP. One thing I noticed is how BSP react to Lumen, compared to regular geometry. While regular geometry makes light bounce very nicely, BSP geometry doesn’t really bounce light. As a comparison, here’s the white hallway scene I’ve been using for my tests.

And here’s a BSP of the house.

Luckily, this is not really an issue. BSP is not supposed to be used to build the actual level. You’re just supposed to use it for prototyping and such. In the case of Just Let Me Go, I am using BSP because I wanted to quickly layout the entire house and easily make modifications as I was putting big props, to define spaces. However, the final house will be made using geometry.

I also began trying out Nanite, but I can’t really say much about it since the project does not have a lot of geometry yet. Besides, a lot of the geometry is very optimized, so the changes are barely noticeable. I think Nanite I something that will play a more important role in future projects that may have more geometry (Just Let Me Go takes place in an abandoned house).

Now that I have been using UE5 more constantly, I notice two things. First, my laptop can get really hot, so I have a tower fan standing next to my desk, blowing air to the laptop. And second, the editor performance is not as good as UE4. If I go by experience, I think performance will improve as more updates are released, since the same happened with UE4 (the first versions of UE4 were very slow, but they gradually became better).

I will continue documenting my UE5 developments as the development of the game progresses.

Sections: Tips + Tutorials

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