Area lights with variable directional light

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Area lights with variable directional light

Postby Piita » Fri Mar 17, 2017 1:12 pm

I have found an increasing need for area lights with a more directional light beam. Not as directional as the laser though. Perhaps a setting so the user could change the spreading of the light beam from what it is now to a more direct beam. Like a spot area light. Would it be possible to add something like this to the area light without much work?

With ies profiles you can get more direct light but I find them a little difficult to work with. You have to go through a lot of them until you find one that works.
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Re: Area lights with variable directional light

Postby Dade » Fri Mar 17, 2017 1:46 pm

Piita wrote:I have found an increasing need for area lights with a more directional light beam. Not as directional as the laser though. Perhaps a setting so the user could change the spreading of the light beam from what it is now to a more direct beam. Like a spot area light. Would it be possible to add something like this to the area light without much work?

With ies profiles you can get more direct light but I find them a little difficult to work with. You have to go through a lot of them until you find one that works.


Distant infinite lights have a spread angle (the parameter is named theta ,default value is 10 degrees), you want the same feature for triangle lights, it shouldn't be hard to add a theta parameter for them too (default value 180 degrees, the current behavior).
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Re: Area lights with variable directional light

Postby burnin » Fri Mar 17, 2017 1:52 pm

oh, yes... theta for Area lights, please :D

also you can make yourself a dozen of IES profiles with IES generator 4 to have them always at hand for any occasion & any other engine supporting IES
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Re: Area lights with variable directional light

Postby Dade » Mon Mar 27, 2017 9:04 am

I'm working on theta support, this is a cornell box rendered with a theta of 30 degree:

theta.jpg


I'm considering to add a linear fall off parameter too.
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Re: Area lights with variable directional light

Postby Piita » Mon Mar 27, 2017 12:42 pm

That is excellent! Thank you
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Re: Area lights with variable directional light

Postby Dade » Fri Mar 31, 2017 7:48 am

I added the support for Material theta parameter:

Code: Select all
scene.materials.Light.type = matte
scene.materials.Light.kd = 0.75 0.75 0.75
scene.materials.Light.emission = 10. 10. 10.
scene.materials.Light.emission.theta = 15.0


image.png


Recursive Materials (Mix and GlossyCoating)

A special note about recursive materials: the theta value of the "root" material is always used (i.e. the one defined in Mix or GlossyCoating). The complexity of supporting recursive theta definitions doesn't look worth of the utility (i.e. nearly zero) to me.
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Re: Area lights with variable directional light

Postby Piita » Fri Mar 31, 2017 11:54 am

Fantastic! Thank you
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Re: Area lights with variable directional light

Postby B.Y.O.B. » Thu May 11, 2017 11:05 am

I guess the default value of the theta parameter is 90?
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Re: Area lights with variable directional light

Postby Dade » Thu May 11, 2017 11:57 am

B.Y.O.B. wrote:I guess the default value of the theta parameter is 90?


Yup, it is.
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Re: Area lights with variable directional light

Postby B.Y.O.B. » Thu May 11, 2017 12:33 pm

Ok, I added support in LuxBlend (and description to LuxCore_SDL wiki page).

For users:
You will need the latest LuxCore binaries, e.g. from the binary sdk: viewtopic.php?f=30&t=13329&start=20#p126536
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