Thanks a lot André - this is cool :)
- MB
----- Original Message ----- From: "André Adam" <a_adam(at)49games.de>
To: <XSI(at)Softimage.COM>
Sent: Thursday, June 28, 2007 11:26 AM
Subject: Re: A couple of RBD questions
There you go. This is JScript. Just select a bunch of objects and you
get a particle cloud which you can drive with any forces. Currently the
script only transfers the objects' positions to the particles, not their
rotations (yep, I have been lazy). In other words, if your objects have
rotation applied, the particles will reset them to 0/0/0, so do a freeze
rotation beforehand if this applies to your scene.
If you want to combine this with RBDs, you can make the objects passive
RBDs and simply switch them to active at any time you like, the RBD
engine will instantly take over and make the objects leave their
particle trails.
Hope that helps, cheers!
-André
Morten Bartholdy wrote:
It sounds good André - I also need to do a load of smaller pieces of
concrete and was just looking into ways to do that on top of my large
piece simulation. I would be hvery grateful if you would pass me that
script. Thanks a lot!
Cheers
Morten Bartholdy
3D & VFX Artist
----- Original Message ----- From: "André Adam" <a_adam(at)49games.de>
To: <XSI(at)Softimage.COM>
Sent: Wednesday, June 27, 2007 5:59 PM
Subject: Re: A couple of RBD questions
I've just done something like this using a combination of scripting,
particles and RBDs. Basically I sketched a particle cloud, one
particle for each object, created a particle cloud with simulation
props from the sketched cloud, then created a cluster constraint from
each object to its corresponding particle and finally used this setup
to shoot the rocks out of the wall using the particle system. As soon
as the rocks did not sit on top of each other anymore I switched the
rocks' RBD properties from passive to active and let the RBD engine
do the floor collisions. Worked out nicely, with a script creating
the particle setup from the selected rocks in one go.
If this workflow would be of help for you I could provide you with
the script to do the setup.
Cheers!
-André
Morten Bartholdy wrote:
I am breaking a wall with RBD and am using a set of pieces which are
slightly smaller then the ones I want to render so I can avoid
interpenetration in the beginnnig of the simulation. Now I know I
can transfer the cache to a clip in the mixer, but if I want to copy
this motion to each renderpiece or constrain these to the RBD'ed
pieces it starts looking a bit complicated. If I create a cluster
with center my RBD is shot. Next thing I would try is to multi point
constrain my renderpiece to the RBD piece but this requires me to
create three clusters on each RBD piece and then three point
constrain each renderpiece to those. Please tell me Softimage
thought of easier ways to handle something like this with up towards
100 separate RBD pieces???
Another thing is my pieces tend to explode a bit away from each
other even though I have made absolutely sure there are no
interpenetrations at the bewginning of the sim. I have increased
simulation and collision acuracy to very high levels without quite
getting rid of this behaviour. Also I have elasticity all the way
down to 0.001 since these are supposed to look like concrete pieces,
but I still get weird styrofoam like bounce and sploinng-like fly
away behaviour from the odd piece when it collides with something
again after landing on the ground. I have tried messing with
friction parameters without much luck.
I am guessing there a tips and tricks I still need to learn about
the wonderful world of RBD'ing so if someone knows a way to dampen
simulation collisions I would be happy to hear them, if someone in
the know cares to share some insight.
Thanks!
Morten Bartholdy
3D & VFX Artist
--------------------------------------------------------------------------------
/*========================================================
"Selection To Particles" / André Adam
Constrains a selection of objects to a newly created particle cloud.
Resets the objects rotation in the current implementation!
========================================================*/
//Create a particle type for later use
var oPTypeRtn = CreateParticleType(siBillboardType);
var oPType = oPTypeRtn.Value("Output");
//Create an empty particle cloud and get its primitive
var oCloud = ActiveSceneRoot.AddParticleCloud(oPType, "Sketched
Particles");
var oPrimitive = oCloud.ActivePrimitive;
//Copy the selection into a new collection to avoid trouble with
selection changes
var cSel = Selection;
var cCopySel = new ActiveXObject("XSI.Collection");
cCopySel.AddItems(cSel);
//Create an empty array and fill it with position data from selected
objects
var aPos = new Array();
for(var i=0; i<cCopySel.Count; i++){
aPos.push(cCopySel(i).Kinematics.Global.Transform.PosX);
aPos.push(cCopySel(i).Kinematics.Global.Transform.PosY);
aPos.push(cCopySel(i).Kinematics.Global.Transform.PosZ);
}
//Create particles in the cloud
oPrimitive.AddParticles(cCopySel.Count, oPType);
//Position particles in the cloud
oPrimitive.Particles.PositionArray = aPos;
//Create a new cloud using the old one as an initial state; the new
cloud owns simulation properties
var oInitialStateCloud = CreateParticleCloud(oCloud)(0);
oInitialStateCloud.Name = "Simulation Particles";
//Make particles live forever
oCloud.Properties("Initial State
Property").Parameters("liveforever").Value = true;
//Create clusters from the new cloud's particles and constrain the
former selected objects to them
var oGeo = oInitialStateCloud.ActivePrimitive.Geometry;
for(i=0; i<cCopySel.Count; i++){
//Create cluster
var oCluster = oGeo.AddCluster(siVertexCluster, cCopySel(i).Name, (i));
//Create constraint and set tangent and upvectors
var oConstraint =
cCopySel(i).Kinematics.AddConstraint("ObjectToCluster", oCluster);
oConstraint.Parameters("tangent").Value = true;
oConstraint.Parameters("dirx").Value = 0;
oConstraint.Parameters("diry").Value = 0;
oConstraint.Parameters("dirz").Value = 1;
oConstraint.Parameters("upvct_active").Value = true;
oConstraint.Parameters("upx").Value = 1;
oConstraint.Parameters("upy").Value = 0;
oConstraint.Parameters("upz").Value = 0;
}
