Collision

[Excelsior47]

Hi,

I'm trying to collide my car with another object using the rbd packed object node. Everything works out well, the objects collide with each other but the car ends up knocking down the tube whatever I do even though I want it to be the other way around.

Sim.hip

[anim]

your car is not active, so it will only affect other rbds, but will not react to any dynamics itself,

you have SOP Solver in there that you probably want to use to activate the car, but for now it's not doing it for 2 reasons:

1. you are enabling it based on simulation frame $SF, but that's different from global scene frame because your sim starts at frame 120, so rather use $F in this case

2. it's just passing the geo through in the SOP solver, so even if it was enabled at the correct frame it would not do anything

 

here 1. and 2. fixed, you may want to add some constraints to the car so that it doesn't just fall apart unless that's what you want

Sim_activationfix.hip

Edited January 13, 2019 by anim

[Excelsior47]

Thanks a lot Tomas! I adjusted the simulation now to my liking and made the car collide at an earlier frame. Now I'm following a tutorial which the person after doing the sim, brings out a Fetch node to transfer the animation to his high res model. What I'm struggling right now is that I can't point out the Fetch node to the dopnetwork because it doesn't show up and even if I try to do it manually by typing it out, it tells me that it can't locate the object.

 

[anim]

what did you type to the Fetch Object parameter?

looks like it's trying to find: /obj/LowPolyCar/dopnet1/LowPolyCar/

while it should be something like:  /obj/LowPolyCar/dopnet1:LowPolyCar

[Excelsior47]

I did try both of these methods but I still get the "Cannot locate object" message. I've uploaded the file if you can check what seems to be wrong as I am completely stuck at the moment.

Fetch.hip

[Excelsior47]

I did try both of these methods but I still get the "Cannot locate object" message. I've uploaded the file if you can check what seems to be wrong as I am completely stuck at the moment.

[anim]

how is your object named in your dopnet1?

[Excelsior47]

It's named LowPolyCar

[anim]

are you 100% sure?

cause in the earlier scene it was called rbdpackedobject1

so your Fetch Object parameter would be: /obj/LowPolyCar/dopnet1:rbdpackedobject1

but that brings us to the problem, that if it is a packed object, you can't use Fetch to get correct transform, because packed objects transform is not updated during the sim, just the transforms of packed primitives themselves

Edited January 13, 2019 by anim

[anim]

aaand annother issue, seems like Fetch Object can only fetch objects from object level Dop networks, which seems like a bug

so even though your path may have been correct, you will get an error

however it wouldn't give you meaningful transform anyway  if your objects are packed

for packed objects there is much more common workflow to pack Hi Res as well and use Transform Pieces SOP to match the transform

[Excelsior47]

Thanks for the response Tomas! But how exactly does the Transform Pieces SOP workflow go? Is there a tutorial somewhere I can see and go from there?(I'm a bit new to Houdini). Also, yeah I did change the the object name before from rbdpackedobject1 to LowPolyCar but I guess that doesn't matter now. 

[Excelsior47]

Hmmm I played around with the Transform Pieces node and I managed to connect my Hi res model to my low res one but it's not in the right position and it doesn't rotate

[Excelsior47]

I actually wonder as well if you happen to know of a easy way to bend the car at the point of impact