Dynamics Error message

# 1 07-04-2013 , 12:29 AM

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Hello
I have been having trouble in Maya 2011 with Dynamics.
So I ran a simple test to illustrate. Create CUBE, add Vortex and then PLAY but does not work as expected. And this error message shows up.
Warning Cycle on pCube1.worldMatrix[0] may not evaluate as expected.

I have no idea what that means.
Help please.
Dan
thanks

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# 2 07-04-2013 , 02:59 AM

EduSciVis-er
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It's pretty harmless, it just means that the playback can't evaluate the dynamics correctly for example if you scrub backwards or skip frames. Check that your playback is set to play every frame.

-stwert

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# 3 07-04-2013 , 05:14 PM

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I deleted my Prefs

stwert
thanks for the input.
I checked play everyframe - it was not set to that.
And I deleted my Prefs, do you know if you have to delete the whole pref files or just the mel files in prefs folder?
After I deleted the mel files in prefs, restarted my machine and I cannot get dynamics to work.
Again I am using 2011.
I have 2013 - and it works there?

All and any help would be awesome.
Dan

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# 4 07-04-2013 , 10:02 PM

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Looks like Maya is complaining that you haven't moved your cube from the origin so the simulation will be wonky.

Executing the code...

Code:

cycleCheck -e off;

...will stop the warning but won't change the simulation. Does the same scene simulated totally different between the two versions?

Also, you never really have to delete all your prefs, especially if you're unsure if it's even the source of your problem, all you have to do is close Maya, rename any given file or folder associated with Maya settings and launch Maya again, new defaults will be made.

- Genny
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# 5 08-04-2013 , 12:12 AM

Technical Director
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I checked play everyframe - it was not set to that.

Originally Posted by danielchappelle

I don't think you understand. When working with dynamics, play every frame MUST be on!

Also, in case anyone is interested, this is not a harmless warning! This will cause your scene to simulate extremely slowly in some cases, and as it says, may give incorrect results.

The backbone of Maya is the DAG, or Directed Acyclic Graph. This means that each node's output is directed into another node, and acyclic, meaning that you can't have cycles. Eg, you can't have cube1.translateX connected to cube1.translateX. What the warning you're getting is telling you, is that something you have done is creating a cycle. With dynamics, the previous frame affects the simulation for the next frame. If you scrub through the time line, it does not have the previous frame, and therefore the simulation is missing a key piece of information that it needs to simulate properly. Without this, you get unexpected results, as it says in the warning.

Imagination is more important than knowledge.

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# 6 08-04-2013 , 01:22 AM

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Join Date: Dec 2006

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I don't think you understand. When working with dynamics, play every frame MUST be on!

Also, in case anyone is interested, this is not a harmless warning! This will cause your scene to simulate extremely slowly in some cases, and as it says, may give incorrect results.

The backbone of Maya is the DAG, or Directed Acyclic Graph. This means that each node's output is directed into another node, and acyclic, meaning that you can't have cycles. Eg, you can't have cube1.translateX connected to cube1.translateX. What the warning you're getting is telling you, is that something you have done is creating a cycle. With dynamics, the previous frame affects the simulation for the next frame. If you scrub through the time line, it does not have the previous frame, and therefore the simulation is missing a key piece of information that it needs to simulate properly. Without this, you get unexpected results, as it says in the warning.

Originally Posted by NextDesign

It's weird, the problem occurred when I created a cube, then created a vortex field (with the cube still selected) and hit play.

Scratch what I said about moving the cube, the warning still pops up. Now I'm really curious, going to do some poking around later.

- Genny
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# 7 08-04-2013 , 05:16 AM

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It only happens to me when I jump to the start of the playback range. This is due to what I said above, with the solver not having enough data to simulate the new state.

The documentation for cycleCheck states the following:

Note that it is possible for evaluation cycles to occur even where no DG connections exist. Here are some examples: Nodes with evaluation-time dependent connections: An example is expression nodes, because we cannot tell what an expression node is actually referring to until it is evaluated, and such evaluation-time dependent nodes may behave differently based on the context (e.g. time) they are evaluated at. If you suspect a cycle due to such a connection, the best way to detect the cycle is through manual inspection.

Originally Posted by

Imagination is more important than knowledge.

Last edited by NextDesign; 08-04-2013 at 05:21 AM.

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# 8 08-04-2013 , 01:35 PM

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thanks NextDesign & others

thanks NextDesign
your explanation was interesting to say the least

I haven't had a problem with dynamics and I have been using Maya since it was Wavefront.

And the simulations work for me in 2013 as well as 2011 - that is until 5 days ago when I just wanted to do some fields simulations.

So simply put can't I start a new scene - create cube- apply gravity and then just hit play - with everyframe option turned on - and get a result?
dan

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# 9 08-04-2013 , 02:34 PM

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So simply put can't I start a new scene - create cube- apply gravity and then just hit play - with everyframe option turned on - and get a result?

Originally Posted by danielchappelle

You sure can.

Imagination is more important than knowledge.

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# 10 08-04-2013 , 09:29 PM

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no result

NextDesign
When I do steps above I get no result - obj does not move.
I am close to thinking I should do a clean install of Maya 2011.
It was working, I am just not sure when it stopped working - may be conflicting plug-in etc.
Dan

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# 11 08-04-2013 , 10:44 PM

Technical Director
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Try the following before you do that:

1) Make sure play every frame is on.
2) Create a cube, attach a rigid body, then apply gravity to it. See if that simulates when you click play.
3) Go to Modify>Evaluate Nodes, and click on Evaluate all. Check if it simulates now.

Imagination is more important than knowledge.

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# 12 13-04-2013 , 10:32 AM

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evaluate nodes

this did not work either?

I must have something turned off or disabled....

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# 13 18-04-2013 , 05:40 PM

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fixed problem

I have RealFlow and PDI installed and had both plugins enabled.

After I turned them off - Dynamics works again as normal.

Thanks for all advice.
dc

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# 14 18-04-2013 , 08:01 PM

The thin red line
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Location: England

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I have RealFlow and PDI installed and had both plugins enabled.

After I turned them off - Dynamics works again as normal.

Thanks for all advice.
dc

Originally Posted by danielchappelle

Thanks for sharing that it might help out some one in the future.............dave