Changing light from static to movable breaks it

I have been chasing a particularly troublesome lighting issue and encountered this oddity. I have only checked this on Windows and Mac due to an issue with linux’ light building, but it is consistent.

To reproduce the issue :

  1. create a new, blank project
  2. delete the sky sphere, directional light and atmospheric fog
  3. create a point light with : x=0, y=0, z=600000; STATIC; intensity=49999998976.0; attenuation radius=1000000.0.
  4. Build. You should now see the floor in preview and play mode.
  5. Convert the light to Movable and build, and everything will go dark.
  6. Convert back to Static and rebuild again, and the light returns.

I am only just leaning about lighting so maybe it’s something I don’t understand, but it seems to me like a “feature”. :wink: If not, please point me to some resource to help me understand this?

Thanks!

CLARIFICATION : in step 5, it will remain dark in both preview and play modes.

Hi Eredin -

What you are experiencing is an Engine Optimization trying to keep Dynamic Lighting costs (those incurred at runtime in real time). Since Static Lighting is baked, the engine can handle the intensity and distance calculations required as they are not done at runtime but are a texture which loaded at runtime (1 texture versus millions of Photon traces).

If you are wanting to have a light source like this we recommend a directional light which calculates as an infinitely far light source facing the direction you have pointed it. These calculations are more reasonable as you do not have to draw a trace from point source to object every time.

If you need a point source at a moderate distance, also try to turn off Inverse Square Falloff in the Details Panel, this can keep you from having to increase the intensity to huge values to spread the light.

Thank You

Eric Ketchum