Hello,
First of all, I’m new to lightning. With that said I would like to ask the following:
How does lightning works regarding performance?
I experience major performance losses when placing lights. My current situation: A very simple scene with 18 point lights (Stationairy) causes a FPS drop from 60 to 12. This was caused by overlapping lights. When I unable the cast shadows of the lights it causes a drop from 60 to 50 FPS.
Since I am new to lightning and I could not find a complete lightning tuturial regarding performance I would like to ask if someone could explain the basics of lightning performance to me (I have read the documentations). I would like to know:
The basics of lighning performance.
Wich are all the factors that causes performance hits?
Wich effects do those factors have?
What are possibilities to improve performance regarding those factors?
Which effect (pro’s and con’s) do those improvements have?
How to use lights in a large scene? (e.g. attenuation radius, strenght, etc. and its performance)
And everything else I forgot to mention.
Thank you very much in advance and kind regards,
ERuts
Note: I do not seek an answer to improve my current scene but am seeking for knowledge regarding lightning performance.
Hi ERuts,
Dynamic Shadow casting lights are the most expensive and this largely depends on the number of shadow casting meshes in the scene along with number of dynamic lights in the scene.
Stationary Point and Spot lights are meant to be used to bake static lighting for all static objects in the scene and provide dynamic lighting for movable objects and characters. When more than 4 of these overlap they will show a red X over the light and will default to Dynamic lights. This can be the performance overhead you’re experiencing.
When these lights are set to not cast shadows, since they are defaulting to dynamic it is why you’re seeing performance jump back up.
The biggest thing to do when running into performance issues where you’re seeing a significant drop in frames is to use profiling to narrow down where this is happening.
These two pages should help explain how to do this:
To briefly answer your other questions.
Performance hits can happen with dynamic and static lighting. With static lighting, have extremely large Lightmap resolution can increase your texture memory footprint and cause performance issues. Using dynamic lighting will depend on the lights settings with radius, strength, how many objects are casting shadows, etc. When lighting large scenes, It’s best to understand what your target platform is, whether you’ll need dynamic or static lighting, lighting the scene appropriately and then profiling to see where the biggest hits are coming in. When you narrow down the performance hits you can then start to refine your scenes more to fit your system specs or the target system specs.
Thank you!
Tim
Thank you for your reply. It was very usefull.