As I have an animation on object level, and I want to inherit velocity from this animation in DOPs, I create, as the help says, a trail node to compute velocity on SOP level.

But as I see in the node info, v=0 and the simulation just falls from the specified frame (of course, if v=0).

Any clue about inheriting velocity on DOPs from existing animation?

Many thanks.

My first suggestion would be to get rid of the Trail Sop, and instead select your object in the viewport and hit the “Static Object” tool on the Rigid Bodies shelf. This will pull your object, including all animation and velocity information, into your DOP simulation. Your problem right now is that you are passing control of your object to the RBD Solver. The RBD Solver is making your object behave according to the rules of physics. You don't want this, you just want your animation. So you need to get rid of the RBD Solver. Just look at the way the tool sets up the DOP Network and you'll be able to figure out how to build this kind of setup yourself (if the interactive tools don't give you exactly what you want).

Mark

Well, with this what I do is input my anim on DOP leve, so I can do blending between RBD and OBJ level keyframe, for example. Right?

But what I need/look for is to inherit the velocity generated from that animation and use it as impulse of my RBD sim on the creation frame.

I´ll try it around before ending with the blending (which is great BTW! )…

Many thanks.

You can do the blending between RBD and keyframed whether the animation is done at the DOP or object level. Both setups are possible. You just need to set the OBJ Path parameter on the RBD Keyframe DOP to grab the object level animation. But feel free to do it either way.

As for getting the first-frame velocity, all our velocity calculations (from the Trail SOP or in the RBD Keyframe DOP) are done by comparing the current frame position to the previous frame position. So on frame 1, where there is no previous frame, the velocity is going to be zero. The easiest solution to this is to use an RBD Keyframe Active DOP to make your RBD Object Passive one frame 1, and active on frame 2. At frame 2 it will compare the position to the frame 1 position and generate the velocity values.

If you really want the velocity set on frame 1, it might be easier to set explicit values in the Velocity parameter of the RBD Object DOP. You can either use specific values or expressions based on the object position (even basing it on the current position and the _next_ frame position if you want to get really fancy).

Mark