LuxCore technical problem, Light cannot pass through Area

[wizard3376]

The problem with (Area) in the first image you can see that the laser does not pass through completely, but only halfway, this is due to the fact that ((Area) the red light source) is blocking the laser from passing through, and also (Area) is blocking all light sources, this can be seen in visualization 2, there is no red sun. This is not true. Correct when the light source (Area) transmits light. For example, in visualization 3 there is a sun and in visualization 4 nothing interferes with the laser

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.blend file: https://drive.google.com/drive/folders/1_93Rijk5PHeUSHwM_WNjHTceJRrf76U0?usp=sharing I have prepared the scene for you, here you can clearly see this problem, the red folders indicate the problem with the light, the green folders show how it should work (Area)

OS: Windows 10 Blender version: 4.0.2 LuxCore version: 2.8 alpha1

[CodeFHD]

Findings from an analysis today:

It doesn't appear to be a bug, though it is not clear to me either to which degree this was explicitly intended/accepted behaviour.

Under the hood, the area light is a mesh with black matte material and emission node. The visibility setting only toggles the "transparency.shadow" property. not "transparency.front" and "transparency.back". The latter two are what happens what a materials "opacity" does.

Some discussion on this topic can be found in an older forum thread, though with different examples: https://forums.luxcorerender.org/viewtopic.php?t=2310&hilit=area+visibility

I suggest to give this further consideration before any changes are made.

• Simply changing the are light transparency export would break older scenes with similar setups.
• It might be possible to offer mutiple "visibility settings" or expose opacity separately for the area light.
• It might be possible to use a non-intersectable triangle-light from the Core features instead of a mesh with emission (again as a new and separate option)