I am new to Krakatoa and am busy considering it for a number of future projects as it seems like a very flexible solution for particles and point clouds. However, I have a few specific requirements that it isn’t clear whether Krakatoa will support.
Essentially, I would like to import a large particle file and make a proportion of those particles ‘lights’.
From my initial searching I can see that you can make particles self-illuminating which seems like it may offer the solution I would like, but I am wondering how much self-illumination you can create? Ideally, I would like each point to become an omni-light equivalent and have some control over fall-off and other parameters.
Has anyone tried this, or something similar? It may be there is a better way to do this, and I would be grateful for any suggestions.
Unfortunately, the Emission channel of Krakatoa does not turn particles into light sources. It does not control how much light they emit into their environment and neighbor particles would not get illuminated by that energy. It is more like the Self Illumination of Standard materials in the Scanline renderer - light arrives at the camera without an explicit source. Also similar to Ambient light which is without a specific source.
We have logged a wishlist item for allowing the Emission to affect other particles, but this is not directly possible in the current renderer.
However, it is indirectly possible using two particle clouds and a Magma channel modifier. I don’t have an example from Krakatoa MX, but I do have one from KMY. youtube.com/watch?v=Pap1JEuUvVg
In your case, you would assign the Emission to the “source” particles, then sample that channel and measure the distance from each particle in the system to be illuminated and set the Emission channel there to the result. This would not calculate any absorption (light falloff due to passing through a dense cloud of particles), but might still look like what you are after (many light sources within a volume of particles, illuminating within a certain range).
I have been giving this some thought after reviewing the links you posted and I have a few questions, as I still am not sure if it will quite work for what I am trying to achieve.
Essentially the two particle clouds will not be within each other but will be next to each other instead, hence I think the nearest particle node may not work to illuminate the reference particle cloud. In an ideal world I would like each particle within one of the clouds to act as a point light and radiate to the second cloud. Then for the second cloud to interact with that light, with particles absorbing it etc.
Do you think something like this would be possible to achieve with the existing node types?
Nope. You will need to physically create an Omni light at each particle position, for example using MAXScript.
But if the lighting particles are more than 100 or so, rendering will take a while since each light will have to sort and illuminate the other cloud. But I have done this before with 72 lights and the results looked quite good, it was just taking a few minutes to process…
If we are talking about thousands or millions of light sources, you can probably forget about it.
Ah I see. It would be in the millions I suspect, so I may have to think of an alternative.
Very frustrating for sure.
Thanks for all you help though Bobo. It is much appreciated, and I look forward to the day that the emission interacts with the other scene particles.
Thanks.