Cineversity

Can someone please help me understand what is required in a shader to allow lights to show through?

I have a number of particles that generate omni lights and they appear behind “glass objects”, and they should show through, something like seeing Christmas lights through a window.

I can see lights through the glass objects with the Banji shader.

But if I try to replicate this effect with a regular material, the visible lights disappear.

From one source, I read that the Banji material is a volume shader. Is this “volume” effect the same as the “fog” on a regular shader?

Some other source wrote that none of the regular C4D materials support “volume” rendering.

In another source, someone implied that a 2-sided material is needed for this kind of effect and C4D doesn’t have one.

I also have VRAY, which has a 2-sided material, as well as a “volume” setting on the advanced material, but I would rather use C4D, if possible.

Mostly, I’d like to understand what is required, and to know whether it is possible to replicate the Banji shader in a regular material and, if so, what steps I might follow.

Thanks.

Hi Celumbra,

The main question would be, if Banji does what you need, where comes the need to swap it out from?

Real Volumetric is render intensive. Hence compare it to the Caustic options in C4D, they deliver a nice simulation. There are two ways to get it, with the standard render and light sources and materials (Illumination Tab). Note that the light source differentiates between Surface and Volumetric.
the second way is given in the Global Illumination Render Settings>Options

As I have not seen an image nor a scene file, it is simply impossible to know what your really want. If you use the Banji with a Omni light-object, the surface is illuminated, but I can’t see the light source. If you switch off the “Diffusion” channel in Banji, you get nearly nothing, and switching off the “specular” in the Light object the material gives nothing back. I guess that puts some speculations to rest about this shader.

Would this be close to what you are looking for: Use a normal material. Set up the transparency channel to anything than 100%, perhaps start with 90% (Brightness). Then place in teh Luminance channel the Backlight Shader.

Light sources are normally invisible in C4D, you have to give them “Visibility” to have something at the origin of the light-source.

Let me know if you have an example.

All the best

Sassi

Thank you for your response.

I was advised, perhaps incorrectly, that as a matter of optimization, I should not use the Banji shader since it is an old shader. We have thousands of lights so we are trying to manage the rendering by optimizing everything. Is there any inherent limitation, optimization-wise, to the Banji shader?

I will run some tests, but I am doubting that using caustics with a normal material will be more optimized than the Banji shader, especially with 1000s of lights.

I was also curious to see if we can produce something better looking with the new reflectance channel in r16.

I’ve included an image of the lights behind the glass, using the Banji shader.

Here is the image again.

Thanks for the hint. I guess you have the lights inside of the objects and you like to see them like “fire-flies” in a acrylic tube?

:o)

Yes. Fireflies are the idea: they move around inside the tower. The lights appear to be inside the tube, but the tube is actually made of 8 free-standing panels, which is tricky to see in this particular rendering. The panels also have thickness. And I don’t particularly want an acrylic look, which is another reason to move away from the Banji shader.

celumbra - 08 September 2014 04:04 PM

Thank you for your response.

I was advised, perhaps incorrectly, that as a matter of optimization, I should not use the Banji shader since it is an old shader. We have thousands of lights so we are trying to manage the rendering by optimizing everything. Is there any inherent limitation, optimization-wise, to the Banji shader?

I will run some tests, but I am doubting that using caustics with a normal material will be more optimized than the Banji shader, especially with 1000s of lights.

I was also curious to see if we can produce something better looking with the new reflectance channel in r16.

I’ve included an image of the lights behind the glass, using the Banji shader.

You were advised that the effect that you were trying to achieve was inherently slow because of a mix of a complex shader, volume effects, area shadows, and transparencies, not that it was a limitation of the shader itself.

Aside from that, the reflectance channel will not really affect transparency that much…but I believe I did mention that you can try using absorption. Regardless, there is going to be a certain limit to how “fast” all of this ends up rendering.

Hi Patrick

Yes. Someone other than you advised me against using the Banji shader.

I take it that changing the Banji shader to another, more “modern” one would not be an optimization?

While the render times will be long for this effect, we are looking for as many ways to optimize as we can, even to get the final piece to render at all.

Perhaps this could be a starting point? I have attached a little sketch.

I used the term “Acrylic” here more to identify the objects, not for material qualities, I’m certain you have your ideas already about.

Lights, as long as set up to be only “visible” (no diffuse, no specular in the light General tab), will render very fast. Perhaps, I miss something that you need…

(yes, with thousands of lights, don’t bother with caustics…, if render-time is key)

As a side note, you might use a tracer to get the Particles path converted into Splines, and adjust then the path more to the needs inside the “tubes”.

:o)

P.S.: a more render-intensive solution, but it allows for a nice effect, as the intensity of the resulting “spot on the surface” has a nice variety among all of the lights.

https://www.dropbox.com/s/5ajzmhi5imv7pu8/CV2_r15_drs_14_MGff_11.c4d.zip?dl=0

This is more an “wild” alternative, based on particles and the Proximal Shader.

https://www.dropbox.com/s/ymy2zjpnmlc5r89/CV2_r15_drs_14_MGff_21.c4d.zip?dl=0
(The Target Effector has no function in file _21)

The version that I have suggested vary wildly in render-time and aesthetic. I guess you will know best what might work or at least could be a starting point…

My best wished

Thank you for your files. I will play with them to see what I can learn.

Right off, though, for some reason, I am unable to see the lights when I paste the material in my own scene (works great in your scene). I’ll work with this and get back to you.

Thanks again.

You’re welcome, Celumbra.

Some materials will only work when the scene is working with them. For example check the lights, or the for the Proximal Shader, they need something to work with. Let me know if you need more informations.

All three versions have a complete different aesthetic, but also render-time. I hope you find something to work with.

My best wishes for your project

Sassi