Hello, I’m working on the level lighting and
I’m curious about the cost of each lighting actor, so I’m asking 3 Questions
Please let me know in the order of least cost
Point light (shadows on) VS
Point light (shadows off) VS
point light, (shadows off + simple Light function)
Point light (shadows off) vs spot light (shadows on)
In general, point lights are so expensive that I’m not using them,
but if I turn off the shadows and use them, do they cost the same as normal spot lights?
Not really any clear cut answer to these.
Generally a shadowcasting point light is the most expensive (assuming a moveable light), followed by light function point lights, followed by the light with neither.
The exact cost of light functions is variable however and it is entirely possible to write one that is extremely slow. This also depends on the version of the engine you are in, as 5.4 introduced light function atlasing, which can make using them more efficient.
The exact cost of shadows is also variable, because Unreal has like 8 different cast shadow methods. For example, if you are using baked lighting then shadows from static lights are effectively free…
Not guaranteed but I would usually expect the unshadowed point light to be cheaper. (again… assuming moveable)
I would expect the cost to be similar provided they cover the same amount of pixels on screen. Point light may be imperceptibly cheaper because it is easier to compute.
Realistically though a point light is more likely to end up covering more of the screen than a spotlight which will make it more expensive in practice.