Hi all,
Suppose there is any animated object guess “sphere” for 0 to 100 frames. and box loaded with pflow>position object set to volume with 1 million particles and sphere is moving in the volume of box for 0 to 100 frames.
Now loading that saved 1 million particles with PRT loaders and using sphere and we want to position particles in sphere volume. so is it possible do particle culling for animated object? I havebeen busy with project and want to make something after project but i havn’t tested it yet. if anyone tested it, give some input.
Thanks,
-J.
http://www.jhjariwala.com <— WebSite
As I know it works with animated objects.
Krakatoa looks every single frame for culling objects geometry itself, I think 
I have here a volume selection updating a culling object and it works
http://www.b3d-animations.com/tmp/dest_city_krak_1.mov
regards,
Bandu
There are two modes in Krakatoa that cull particles:
A) Matte Objects remove particles at render time. So if you saved your box particles to PRT files from PFlow, you can define the sphere as Matte Object and it will not render particles that are behind the sphere. NOTE that this mode also supports correct motion blur from a moving object (albeit motion blur from deformations is not supported yet by the Krakatoa built-in Motion Blur) and that all particles occluded by the sphere and not just the particles inside the sphere will be skipped by the renderer.
B) Volume Culling - this mode is supported inside the PRT Loader and it skips particles as they are being loaded. It can be used to render only particles that are inside a volume or outside of a volume, but it is a loading-time process and does not remove particles relatively to the camera, only relatively to the volume. It can be used to model/cut/carve or reveal particles.
Known bug - there is some leaking going on caused by a bug in the raytracing structure which we are trying to fix before 1.0. It can affect both Matte and Culling operations.
See this thread on CGTalk:
http://forums.cgsociety.org/showpost.php?p=4101171&postcount=8
Forgot the important part of the answer -
both are animatable and should update once per frame. Matte Objects motion blur takes into account the particle positions and their velocities plus the shutter value and offset.
Thus, it calculates the lighting just once and renders multiple passes using the same data, interpolating using the positions and velocities. It also loads the matte objects just once into the raytracing structure and extrapolates their positions based on their Position/Rotation/Scale values.
This makes the Krakatoa Motion Blur very fast as it has to prepare data just once, but at this point it cannot sample the geometry deformations at a sub-frame step.
Since Krakatoa supports the Max Camera Multi-Pass Motion Blur effect, you can also use that, but it would load particles and matte objects, light the particles and rebuild the raytracing structures once per sample, so it would be orders of magnitude slower to calculate, but would take into account deformations and would look much like the Max version of the effect.
Volume culling is also animatable, taking into account both the PRT Loader’s position and the culling volume’s position, so you can animate either one or both to create visual effects. The culling does not sub-sample or interpolate the motion of the culling volume for motion blur purposes - it culls particles on the current frame while they are being loaded from disk, then the lighting and rendering is performed on those who were not culled. Motion blur will be applied to the particles based on their velocity, but not based on the velocities of the PRT Loader or Culling Volumes. So this mode is not very good for creating compositing effects, plus it does not occlude particles behind the culling object relatively to the camera.
Choose your weapons!
Andrzej, i have a quick question about your dest_city_ animation movie…
First let me say that i think it looks pretty cool
I was wondering if you could\ did made a test with the Particles Colliding on the Left Over Buildings As they are Beeing “dust borning effect” and See\saw how did Krakatoa Interpolation positions and Velocitys Looks Like … I would be interested to see how bad\good it can handle deflection on those new created interpolated points … i m assuming it dosnt have any kind of Internal Thing telling it that "hey , the particle source is set to collide on those objects , so i cannot make the points that i m interpolating born or pass through them but actually deflect on them as well "…
just a though , if you have the time , that i would apreciate to see …
regards, and again , i like that test
www.cgfluids.com
Hi Rif,
I actually did some tests to see the bouncing distortion and it’s not bad
http://www.b3d-animations.com/tmp/collisiontests1.mov
regards
Bandu
Interesting… so that accumulation we are seeing is a Visual Illusion then… or are you using any Box toolkit of Oleg using Novodex from his side for interparticle collision or something ?
I can feel a stardart deflection method on the box for example and the floor, but the particles themself are interpenetrating correct ?
Specially in the first test ( 1\3) i really liked the smoothness in it in the way its showing that stacking illusion … I m gessing that the last one needs more subsamples for the high velocity created ? is it from the Particle side missing or their is something needed to be Aditivly Sampled from the Krakatoa side ?
thanks for taking the time to share that.
www.cgfluids.com