Lighting on PBRMaterial

Questions
1

Hi,

I am trying to add SpotLight in the scene, and what I noticed is that it shows on the StandardMaterial but doesn’t show on PBRMaterial affected with environmentTexture (hdr map). Is it suppose to be that way, or I am missing something here.

image
image.png1245×895 126 KB

2

This is because the lights are treated differently by the PBR material.
By default, light intensities are computed using the inverse squared distance from the source. This is a type of falloff that is pretty close from what light does in real life. So, the further you are, the bigger your intensity will need to be to reach a surface.

To even go further, the intensity you define on the lights follows physics notions:

  • Point and Spot lights are defined in luminous intensity (candela, m/sr)
  • Directional and Hemispheric lights in illuminance (nit, cd/m2)

The StandardMaterial does not take all of that in account.

To have the PBR to behave like StandardMaterial you can call

pbr.usePhysicalLightFalloff = false;
2 Likes
3

Yes that makes sense. I even found "usePhysicalLightFalloff " in documentation, tried to check off in the babylon inspector, but somehow I didn’t get proper result.

Thank you so much for fast answer, that’s what I needed.

1 Like