Python Computer Graphics Kit

Hi Matthias:

I have been thinking about the problem that the collision geometry and
the real geometry weren't the same.

I think I need to define my collision geometry exactly as the real
geometry, because this would influence the robots behaviour. I am
trying to simulate the robot in a context where it must learn, and the
real geometry is very important.

I have been looking at the CCylinder objects in cgkit and in pyode (and in =
ode).

I have found out that the new version of ode does provide a Cylinder
class, and I have been playing around with pyode, and managed to
actually built a cylinder out of a CCylinder (pyode doesnt yet have
the Cylinder object).

My question comes when I try to build the same CCylinder in cgkit. I
am not getting the same results, since apparently the cgkit CCylinder
is actually more like a capsule instead of a cylinder.

I attach a sample code (a modification of one of pyode's examples),
where you can see what I mean by cylinder (actually in the example I
provide, only a half-cylinder is rendered, but a full cylinder is the
underlying ode object).

Is it possible to build an object like that one in cgkit? How? (The
absolute best would be the half-cylinder, although I think I could
manage with the complete cylinder)

Regards,

Ricardo Kirkner

Re: [cgkit-user] ode geom From: Matthias Baas <baas@ir...> - 2006-05-18 08:12 Ricardo Kirkner wrote: > My question comes when I try to build the same CCylinder in cgkit. I > am not getting the same results, since apparently the cgkit CCylinder > is actually more like a capsule instead of a cylinder. Right, "capsule" is another word for "ccylinder" (=capped cylinder). I believe they are currently about to rename it in ODE. > I attach a sample code (a modification of one of pyode's examples), > where you can see what I mean by cylinder (actually in the example I > provide, only a half-cylinder is rendered, but a full cylinder is the > underlying ode object). You should be able to get the same results with cgkit as you're also using the CCylinder in your sample code (the cylinders never come to rest on their flat side). As you already said yourself PyODE doesn't have the true cylinder yet as this was not part of the official ODE code but was only a contribution. The only difference to a cgkit version would probably be that it uses the actual mass properties of the CCylinder whereas you were using the mass properties of a true cylinder. This affects the behavior of the object but not the collision detection. - Matthias -

Re: [cgkit-user] ode geom From: Ricardo Kirkner <ricardokirkner@gm...> - 2006-05-19 11:54 Hi Matthias: I have managed to create my own geometry class, but in order to do that, I had to put the .py files in the cgkit directory, and to modify the odedynamics.py file to include my geometry class in the test it makes when creating a corresponding ode geometry for that object. Is this the way to add custom geometry classes, or is there a "cleaner" way= ? pd: I have tried several ways, but it only worked when I inserted the geom class in the cgkit directory On 5/18/06, Matthias Baas <baas@...> wrote: > Ricardo Kirkner wrote: > > My question comes when I try to build the same CCylinder in cgkit. I > > am not getting the same results, since apparently the cgkit CCylinder > > is actually more like a capsule instead of a cylinder. > > Right, "capsule" is another word for "ccylinder" (=3Dcapped cylinder). I > believe they are currently about to rename it in ODE. > > > I attach a sample code (a modification of one of pyode's examples), > > where you can see what I mean by cylinder (actually in the example I > > provide, only a half-cylinder is rendered, but a full cylinder is the > > underlying ode object). > > You should be able to get the same results with cgkit as you're also > using the CCylinder in your sample code (the cylinders never come to > rest on their flat side). As you already said yourself PyODE doesn't > have the true cylinder yet as this was not part of the official ODE code > but was only a contribution. > > The only difference to a cgkit version would probably be that it uses > the actual mass properties of the CCylinder whereas you were using the > mass properties of a true cylinder. This affects the behavior of the > object but not the collision detection. > > - Matthias - > > > ------------------------------------------------------- > Using Tomcat but need to do more? Need to support web services, security? > Get stuff done quickly with pre-integrated technology to make your job ea= sier > Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronim= o > http://sel.as-us.falkag.net/sel?cmd=3Dlnk&kid=3D120709&bid=3D263057&dat= =3D121642 > _______________________________________________ > cgkit-user mailing list > cgkit-user@... > https://lists.sourceforge.net/lists/listinfo/cgkit-user >

Re: [cgkit-user] ode geom From: Matthias Baas <baas@ir...> - 2006-05-22 08:37 Ricardo Kirkner wrote: > I have managed to create my own geometry class, but in order to do > that, I had to put the .py files in the cgkit directory, It should work in any directory. What happened when the file was outside the cgkit directory? > and to modify > the odedynamics.py file to include my geometry class in the test it > makes when creating a corresponding ode geometry for that object. Right, the ODE stuff is not really meant to deal with user defined geometry. You couldn't add any new functionality anyway. All geom objects that ODE supports are already available in cgkit and you can also do composite objects. So anything your new class is supposed to do should already be possible with the existing classes. If you still need your own class, it's probably best to derive from one of the GeomObject classes that are already checked by the ODE stuff (SphereGeom, CCylinderGeom, BoxGeom, TriMeshGeom). - Matthias -

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