If you look at Audi's matrix light technology, the car's headlights recognize other cars and only dim the light in that area.

I wanted to express this in Blender. I tried a few things, but didn't get satisfactory results.

The method I tried was to shine a light on an object, make the object transparent, and then only cast a shadow. And by using the constraint options (Copy Location, Limit Distance), the car that shoots light and the car passing by are in a straight line so that the dark area follows the car. This method was fine, but it was awkward because the edges of the shadows were too sharp.

This is first method that I used.

Another way was to use Image Texture. I tried using an image with black bars on a white background and shining it with a spotlight, but the results were just randomly lit.

Also, the dark areas didn't make it follow the car. This method was very different from what I wanted.

This is second method that I used.

Here is an example video that I would like to follow.

enter image description here


I want to follow the part from 0:57 to 1:02 of the video.

I want to make the dark areas look natural, like in the video, and make the areas follow the car and disappear. Is it possible to express something like that using nodes or using image textures? Blender experts' help is desperately needed...

Thank you.

  • 1
    $\begingroup$ You can force a light source to cast a shadow instead by giving it a negative wattage value (this also has the effect of negating light from other sources) - perhaps you could parent a (disabled) spotlight with a negative wattage to each of the "other" cars, and then find a way to enable it when the respective car comes within proximity of the "main" car. Given the limited angle between when the light first hits the car and where it is when it passes out of the spotlight stream, you may not even need to make the shadow source (-light) move (or track) the lights as it passes. $\endgroup$ Mar 13, 2023 at 5:20
  • $\begingroup$ jesus that was perfectly I wanted thanks a lot christopher $\endgroup$
    – 미젤로
    Mar 13, 2023 at 6:45

1 Answer 1


Here's a cheeky hack, some variation of which may be good enough, and fuss-free..

Create a shadow-casting material, which is otherwise invisible:

enter image description here

On objects which are supposed to be interpreted as cars, assign this GN group:

enter image description here

.. which makes a copy of the object as its convex hull, scales it towards the selected lamp, and assigns the shadow-cast material to the copy .

Which makes this difference:

enter image description here

The generated shadow-caster can have its relative dimensions and distance-from-lamp adjusted. You can tweak those for the desired effect, depending chiefly on the radius of the lamp.

  • $\begingroup$ I'll have to study the geometry nodes, but that's exactly what I wanted though. Thank you very much. $\endgroup$
    – 미젤로
    Mar 20, 2023 at 6:00

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