Hi guys
I’m new to Krakatoa but have been doing some experimenting and I love it!
I’ve had some really nice results using partitions with xparticles sims controlled by TFD fluid.
There’s one thing I don’t really understand though - I think I might just be being thick.
In what practical situation might you use a PRT volume? Sinse you’re not able to manipulate Krakatoa particles with forces or effectors, I don’t see the point of using them - why not just render the orginal mesh with materials? Am I being really stupid and missing something here?
B
This is a pretty good question actually 
And there is no clear answer, but I will try my best:
First of all, a PRT Volume is a great tool to use while learning Krakatoa. Pick a mesh, make a PRT Volume, hit render, you get your millions of particles in nearly no time.
Second, there are cases where you are rendering a scene where an object made of particles makes more sense (integration-wise) than rendering the surface of the same object in another renderer. PRT Volume “steals” all the relevant channels including normals, mapping coordinates and even generates Velocity from the deformations, and then interacts with light the same way all other particle systems do. So you can have an object that looks like your mesh, but renders like your particles with all the light attenuation, shadow casting and receiving with other particles etc. Esp. in Krakatoa C4D where shadow casting from particles into meshes is not resolved yet, this can be very useful.
Third, the PRT Volume IS somewhat animatable. You cannot perform dynamic simulations like with TP or XP, but you can have animated meshes turned into animated point clouds. Or you could keyframe the Shell parameters to produce some kinds of animated reveals and solidification effects…
Last but not least, in other versions of Krakatoa (e.g. 3ds Max), a PRT Volume is a great initial particle distribution object for other sub-systems to run with. For example, you could save a PRT Volume as PRT files and load in Particle Flow, Thinking Particles, FumeFX etc. and use as initial cloud that can be animated further, or can be used to emit other type of data into the system. Or it can be used to seed particles directly into Stoke MX, with all the channel control that a Magma modifier on top allows. Or it can be meshed directly by Frost MX… Of course this does not help a Krakatoa C4D user much (yet), but since we had a PRT Volume in Max and Maya, it was only logical to have one in Cinema 4D. So even if you don’t find any use for it in the first 3 cases above, you can think of it as a compatibility/legacy component
In general, it is better to have a tool and never need it, than not to have it and need it even once…
Hi Bobo
Thanks for your detailed response, much appreciated and very interesting - especially being able to cast particle shadows on an object.
It’s interesting that 3DS max users are able to manipulate PRT objects with by its particle system effectors. I’ll put in a feature request to the guys at Xparticles as this would be amazing (I’m not a programmer so have no idea if this is possible with the X particle architecture or not).
I had one more quick question!
I really enjoyed your presentations at NAB, but there was one thing I couldn’t get my head around. In the Mini car demonstration I couldn’t work out how you got the camera projections to work in 3d space so you’re able to rotate around the car 360 degrees. Was the projection texture a clip sequence with exactly the same camera movement as the camera in the scene?
B
Exactly. You can do the same in C4D - just render your mesh with the same camera move, and then project onto the moving particles. The animated texture will match your camera on each frame, while sticking to the particles. Of course, if you look through a different perspective at the result, you will see the colors streaking through the cloud. It is all smoke and mirrors, but it looks great 