Is there any material or config that can make an object not affected by lighting in the scene?

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richardbao
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Is there any material or config that can make an object not affected by lighting in the scene?

Post by richardbao » Wed May 12, 2021 2:54 am

Hey guys. we are integrating luxcore into our own 3D application, and we met a problem with changing the background for our archviz scene.
we are using HDRI IBL for lighting the scene. here is what we got in the render.
Screenshot 2021-05-12 104137.png
as you can see, the HDRI image can be seen from the window, which may not look pleasant and not predictable. so we are considering changing the background for the render.
what we are going to do is to add a skydome, and put a png background inside the skydome, since we are enabling single side rendering. the skydome won't affect the lighting. but we could see the background from inside, which should perfectly solve our problem, hopefully.
the problem, for now, is the skydome looks dark in the scene. so I was wondering if there were any material that can make the png image not affected by the lighting in the scene. or are there any configs that could help this work? or something like shaderless like blender did with cycle.
besides, any other suggestions on how to achieve the goal would be appreciated.
thanks in advance!

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Dade
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Re: Is there any material or config that can make an object not affected by lighting in the scene?

Post by Dade » Wed May 12, 2021 9:57 am

richardbao wrote:
Wed May 12, 2021 2:54 am
any other suggestions on how to achieve the goal would be appreciated.
You can enable Alpha channel and use BACKGROUND_IMG plugin to replace the back ground (all pixels where rays hit nothing with any image you want) like in this example: https://github.com/LuxCoreRender/LuxCor ... ackimg.cfg

Code: Select all

# Film image pipeline plug-ins
film.imagepipeline.0.type = TONEMAP_LINEAR
film.imagepipeline.1.type = BACKGROUND_IMG
film.imagepipeline.1.file = scenes/simple-mat/sky.exr
film.imagepipeline.1.gamma = 2.2
#film.imagepipeline.1.storage = byte
film.imagepipeline.1.storage = half
film.imagepipeline.2.type = GAMMA_CORRECTION
film.imagepipeline.2.value = 2.2
# Film outputs
# Alpha channel is required by BACKGROUND_IMG
film.outputs.0.type = ALPHA
film.outputs.0.filename = luxball_ALPHA.png
It should do exactly what you are looking for.
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richardbao
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Re: Is there any material or config that can make an object not affected by lighting in the scene?

Post by richardbao » Thu May 13, 2021 6:19 am

Thanks Dade, I'll try this.
and for the shaderless material, will there any plan for including that?

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Dade
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Re: Is there any material or config that can make an object not affected by lighting in the scene?

Post by Dade » Thu May 13, 2021 11:03 am

richardbao wrote:
Thu May 13, 2021 6:19 am
and for the shaderless material, will there any plan for including that?
Not for the moment but you have holdout and Object ID AOV for any kind of specific post-processing, you may need, of pixels covered by an object.
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