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Old 26th Jul 2017, 01:51 AM   #1
amdfe
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Default LightWave - Scalable (and Fake) Light Beams

The Spacedock Interior environment I've been working on contains so many spotlights that I eventually had to stop using volumetrics--as they were killing the render times.

I remembered some older suggestions about using geometry (cone objects) to fake the appearance of spotlights in a scene, so I made a flexible version that would allow me to use a single object that I could clone and scale as needed. [The spotlights in this particular project all have the same color, but they vary somewhat in their beam sizes.]

This method also solved the problem of depicting spot lights with ridiculously small, pointy bases. Normally, if you need a wider base, you can begin the volumetric higher, but then you end up with a light beam that appears disconnected from its source.

I've attached the light beam and a starter scene; feel free to use and tweak as your projects demand.



It's super easy to use:

1. All the gradient effects for luminosity and transparency are based on the beam's pivot point, which is positioned at the base. Thus, the beam will preserve its visual effect regardless of how you size or position it.

2. If you are using actual lights, then parent the beam to the light; otherwise just parent it to a null or whatever object is supposed to be shining the light.

3. Scale the Z-axis to control the length of the beam; and scale the X and Y axes together for thinner or thicker beams. The light on the right side of the image is the default. The one of the left side has been uniformly scaled 200%. The middle example was scaled to be 50% shorter (z scale = 0.5) and 50% fatter (x/y scale = 1.5).

4. If you're comfortable using the gradient controls, you can fine tune the base size by adjusting the 2nd and 3rd keys (which control when visibility begins) and then lowering the beam closer to its source object.

Note 1. The starship was added to the scene to show that the transparency is working and that you must be careful about running these beams through other objects

Note 2. When rendering a scene with global glow enabled, Don't use the glow surface setting for this object, because you can get visible lines across background surfaces.
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Old 26th Jul 2017, 09:26 AM   #2
amdfe
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Oops! Sorry, but I forgot to turn off the tested glow setting and dial back the base position before I packaged up that original attachment.

If you use the first copy, you'll probably see those white edges and your beams will begin about 10m from the source.

You can either set glow to 0% and adjust the gradient keys as you need, or download this updated lwo file instead.

Finally, I should add that this is an object pretending to be a light; so you may wish to disable interaction with rays and radiosity once in Layout (and remember to do so for each clone).
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Old 3rd Aug 2017, 12:37 PM   #3
billy-home
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Great stuff, I've done similar myself, though I did need a light attached to the cone to illuminate the object the spot was pointing at.
If I may make one small suggestion, try it with the Edge Transparency shader, it helps take the sharp edges from the light cone making it even more like a volumetric light., though it does also thin the cone down, good job it's scalable then
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Old 3rd Aug 2017, 06:39 PM   #4
amdfe
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Quote:
Originally Posted by billy-home View Post
If I may make one small suggestion, try it with the Edge Transparency shader, it helps take the sharp edges from the light cone making it even more like a volumetric light.
Thank you for that suggestion. I did not know about that shader, and had used incident angle (transparency) as a softener, but the effect is too subtle.

There's no problem if that shader has the effect of thinning the beam, because the user can just scale up the thickness.

Thanks again for the tip. I will certainly check that out
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