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I feel like this could be done but a combination of math nodes but I have no clue how to set it up.

I have a spot light with a cone parented to it.

The cone has scatter and absorption.

Is there a way to get rid of the black volume? I just want the light to fade out to transparency. I have tried the gradient nodes but its not working. This is the closest I can get.

enter image description here

enter image description here

I am looking for something like this

enter image description here

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  • $\begingroup$ if you add an alpha channel that dilutes the black? $\endgroup$ – user52430 Feb 17 '18 at 0:43
  • $\begingroup$ Have you tried taking out the volume absorption node? $\endgroup$ – user1853 Feb 18 '18 at 16:10
  • $\begingroup$ Similar question: Creating realistic concert lighting $\endgroup$ – user1853 Feb 18 '18 at 16:11
  • $\begingroup$ And : How to make Volumetric Scatter fade adjustable $\endgroup$ – user1853 Feb 18 '18 at 16:11
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Or use just the emission for the volume: enter image description here

EDIT: Just to give you an idea how it can look like with just emission and render really fast: enter image description here

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  • $\begingroup$ This works very well for what I need it for. Do you have any idea what the math nodes are doing? $\endgroup$ – icYou520 Feb 19 '18 at 18:14
  • $\begingroup$ In my example they are just for mapping the volume gradient from 1, close to light to 0, far from light source $\endgroup$ – Richy Feb 19 '18 at 19:07
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Well I think the gradient might be at least some help to you, if you hook it up to the density. Here is an example with a linear gradient:

spotlamp with volume gradient

Here is the same image with the gradient disconnected:

spotlamp with no gradient

It is true that if there is ambient lighting, a certain amount of volume particles may be visible:

spotlamp with ambient light

Some of that could be mitigated by strategic repositioning of your spot lamp:

enter image description here

and/or dialing back the gradient, for example by altering the "location" component of the mapping node (here I set the X coordinate to -0.2):

enter image description here

Hopefully these give you some ideas for tweaking your setup. (By the way, I did not end up making use of the Multiply node in the group below, but it's another parameter you could play with).

enter image description here

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This is an example of volumetric lighting you are trying to make, volumetric lighting is simple to set up.

  1. First create a cone (since you are trying to make God Rays) and place it over the desired object. In the object tab under "Display", change Maximum Draw Type to Wireenter image description here

  2. Next, add a new material to the cone, and under "Volume" select Volume Scatter enter image description here

  3. Create a spot light lamp and place it above the coneenter image description here

  4. Now select the material added to the cone, open the node editor and have the Volume Scatter node connected to "Volume" on the Material Output. Your node setup should look like the picture below. After doing so you can change the density of the Volume Scatter and change the strength of the spot light lamp to get the desired effect. enter image description here

  5. You should get a rendered result of something similar to this: Here, the strength of the spot light is 600, and the Volume Scatter density is 0.1

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