Change attribute for light distance for 2.80

[SonnyBonds]

Blender 2.80 seems to be using "cutoff_distance" as the attribute for light range instead of "distance".

[Jason0214]

Good catch! Looks like cutoff_distance is the correct attribute to be exported as Godot's range.
https://docs.blender.org/api/blender2.8/bpy.types.Light.html?highlight=cutoff_distance#bpy.types.Light.cutoff_distance

Also It is needed to update the reference_exports (we are keeping a exporting results of all the test scenes we have in the repo for regression testing purpose). If you are not sure about how to do it, I can simply send you a patch about this update.

[SonnyBonds]

Ah sorry, I can update the references when I have time and resubmit.

Regarding the change itself, an alternate route to explore could be to instead approximate the inverse square falloff of Blender with a decently fitted range & attenuation curve in Godot. Not sure how close it'd be possible to get and if it'd be better or not.

[Jason0214]

Regarding the change itself, an alternate route to explore could be to instead approximate the inverse square falloff of Blender with a decently fitted range & attenuation curve in Godot. Not sure how close it'd be possible to get and if it'd be better or not.

I think it is possible to have a more accurate simulation. Find relevant code in Godot and Blender
Godot:
https://github.com/godotengine/godot/blob/8743da90d964f7b9110f6e3578fba30ac810f6ac/drivers/gles2/shaders/scene.glsl#L514

Blender attenuation update:
https://developer.blender.org/diffusion/B/browse/master/source/blender/draw/engines/eevee/eevee_private.h$365
https://developer.blender.org/diffusion/B/browse/master/source/blender/draw/engines/eevee/eevee_lights.c$740
https://developer.blender.org/diffusion/B/browse/master/source/blender/draw/engines/eevee/eevee_lights.c$482
https://developer.blender.org/diffusion/B/browse/master/source/blender/draw/engines/eevee/shaders/lights_lib.glsl$193
https://developer.blender.org/diffusion/B/browse/master/source/blender/draw/engines/eevee/shaders/bsdf_common_lib.glsl$28
https://developer.blender.org/diffusion/B/browse/master/source/blender/draw/engines/eevee/shaders/lights_lib.glsl$14

[SonnyBonds]

Yeah I went down that rabbit hole a bit back. There are some things that makes the two attenuation models not super compatible, but it's possible to make a decent approximation. I just haven't had time to finalize it really. I'll probably submit something in a new PR when I can.

[Jason0214]

Thanks for checking on this.
No worries about time, just do it when you really want to and available.

[basdp]

This fixes the distance (which will otherwise always be 2.5). Note however, that Blender 'distance' is not really the same as Godot 'omni_range'. This is a short term fix/workaround. Long term fix should be to convert lights from Blender's interpretation to Godot.

[basdp]

Although this fixes the problem described, it breaks the tests.

[Jason0214]

Will merge it and fix the test breaking afterwards