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paulselhi
09-02-2006, 05:06 PM
..and yet it seems it just is a bridge to far to set up some simple collisions.

Check this file out : http://www.black-and-white-to-color.com/stuff/defproblem.c4d

Now it does not get much simpler than this, a few cubes set to bounce off a floor and also bounce off each other

No matter how i try setting the pdfelector, particle size travel, user defined travel, geometry, box etc i just cannot get the particles to consistently bounce without penetrating the floor and i cannot stop many of then sinking

I have tried subdividing the hell out of everything, bevelling the cube edges to improve collision detection, using a thin cube instead of a plane for collision but nothing works

Can this be done.. am i again missing the bleeding obvious ?

I mean it really is a simple task, one that many other particle systems will do with ease
Ryusaki
09-02-2006, 06:04 PM
I seems that the cubes not really collide with the surface, only the center of the particle.
There is no real collision between the surface of the cube and the ground.
Sadly i cannot help you, since i am not familiar with thinking particles.

But this kind of physic simulation would be easy if you build it with Dynamics.
.
AdamT
09-02-2006, 06:06 PM
The problem is that TP doesn't use sub-frame sampling, so if a particle collides between frames it gets missed. The only solution AFAIK is to increase the length of your animation and slow down the particles accordingly. Kinda sucks, but that's the way it is.
LemonNado
09-02-2006, 06:40 PM
Yes, TP is crude... It helps to set up a fake geometry which you do not render but use for collisions. You have to fake the fake effets 8-0.
Rainer
paulselhi
09-02-2006, 07:02 PM
Well to stop the sinking a "bodge it and scarper" approach is to use a group change set off by comparing the velocity of the particles, if the fall say below 10 then send the parts to a new group and have a freeze work on them


However it is tricky to make sure that those that have rolled above others are not in mid air when they freeze and also are not part way through the ground ( though this sinking seems to happen when they have slowed so much that the freeze should have kicked in before)

The reason whay i am whinging about this is because i am doing a slow motion animation of a crashing "lump of thingy" and i have the main chunks as actual mesh but the very smaller frags are particles. In slow motion these little issues really show up..not so much the jiggling but the "half sunk" effect really is obvious

edit..ok joy of joys some progress

it seems that the more irregular the particle shape the better the collison dtection and i don't need 2 groups, juts so a pgetdata and feed the particle velocity into a compare node, if less than a set amount then the feed out which goes into a pfreeze which kicks in

however once frozen these particles will not be pushed by other particles. i suppose i could do another test so that if they are hit then they change to a new group that can move and again if they slow down too much then they get frozen again ( hmm will they actually move on impact or just be sent to a new group that since it is not moving will be frozen again ??)
paulselhi
09-02-2006, 07:47 PM
Oh well at least i have managed to get the infamous filling jar almost solved albeit with some strange pills..man

Strange i set the emitter to count 100 but it does not stop, so i set the max particles to do this
http://www.black-and-white-to-color.com/stuff/filljar.c4d
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