nParticle does not update its instancData output attribute

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  09 September 2012
Originally Posted by Aikiman: Im not sure about the ID thing but the other issue is just a refresh thing not a bug. The solver works when cycling through a timestep thats just standard with solvers.


You mean the solver included with the nParticles? Yes, the dynamics solvers are active on time change, but all others are also active on DG dirty action.
However, the particles of the deformed nParticle do update fine, so the nParticle is active not only when the time changes. Its just the output to the instancer.

So do you understand why I am confused or did I misunderstand something?

Quote: Im not sure about the ID

I found out that I had disconnected the nParticle from the time node. After reconnection, everything was fine.
 
  09 September 2012
The particles update because you have a direct input connection into position, in this case deformedPosition which doesnt require Maya to solve anything. The instancer on the other hand relies on the solver to evaluate all its values based on the previous frame which is why it wont update unless you step through time, or you force a dirty evaluation.

Does that make more sense?
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Vimeo
 
  09 September 2012
Originally Posted by Aikiman: The particles update because you have a direct input connection into position, in this case deformedPosition which doesnt require Maya to solve anything. The instancer on the other hand relies on the solver to evaluate all its values based on the previous frame which is why it wont update unless you step through time, or you force a dirty evaluation.

Does that make more sense?


Yes, you mean its the instancer node which does not evaluate.
I haven`t tested so far, but I thought the instancer is allowed to take as input any kind of node which delivers the correct data.
The documentations says about the instancers input attribute:
Quote: inputPoints (inp) : This is where the point data is connected. The point data can only be coming from one source. There is nothing keeping the user from having an API node take several inputs and combining them into a single point data attribute, however.

If we can have any source it should evaluate like a "normal" DG node.
I just had not the time to write such a node and test it.

Quote: The instancer on the other hand relies on the solver to evaluate all its values based on the previous frame

Are you sure the instancer node has to solve anything at all?
 
  09 September 2012
You can use SOuPs arrayToDynArrays nodes as input into instancer. They are designed so that you can daisy chain them together, each one a different attribute.

I think you are right, the instancer wouldnt require a solve to evaluate.
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Vimeo
 
  09 September 2012
Originally Posted by Aikiman: You can use SOuPs arrayToDynArrays nodes as input into instancer. They are designed so that you can daisy chain them together, each one a different attribute.

I think you are right, the instancer wouldnt require a solve to evaluate.


Ok, so I created two networks.
The first is capable of interactively changing the position of particles of an nParticle. It has a instancer node connected.
The second connects to the first network, deforms the the nParticleShape and also has a final instancer node connected ( of course to the deformed new nParticle ).

When I now change the position of the nParticles, the first instancer updates fine and the deformed nParticles moves also, but the second instancer is silent.
And when I deform the nParticles, the second instancer is also silent.

My conclusion is that the ".instanceData" output attribute of the nParticleShape node is not properly connected to changes of the nParticles when the nParticle node gets its positional input data via the "deformedPosition" attribute.

( I still would call that half baked or buggy ; ] )
 
  09 September 2012
Can you share the scene?
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Vimeo
 
  09 September 2012
Originally Posted by Aikiman: Can you share the scene?


Unfortunately, the setup is made with my own nodes, which I cannot share. I will make a screen capture for you.
 
  09 September 2012
Perhaps it is a bug. If you want it to update you could try using a SOuPs arrayToDynArray. I just helped somebody with the same problem as this except they wanted attributes like rotation and objectIndex as well as position. SOuP handles this no problems.
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Vimeo
 
  02 February 2013
I'm sorry for meddling in but I'm trying to do similar thing. I need my cached nParticle shape to be deformed with a wire deformer but after I used the tool my particles disappear. Could please somebody tell me what am I doing wrong?
 
  02 February 2013
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