Changing The "settable" Parameter Of An Attribute?

[jarod]

Hi all,

I have a problem with dg node plugin I'm working on.

When I connect the output of my node to another node eg.

connectAttr -f mynode.output pCube1.translateX;

pCube1.tx becomes locked, (it's "settable" parameter somehow gets automatically set to 0 )

Ideally I would like my node to function like the parentConstraint node does. ie. when

connectAttr -f pCube2_parentConstraint1.constraintTranslateX pCube1.translateX;

pCube1.translateX remains "settable".

However at this stage I'd happy with a manual solution to change the settable parameter of an attribute.

Any ideas?

[joojaa]

Well you could try to make it as a constraint node then it would robably inherit the behaviour.

But i was and still am under the impression that its actually the setKeyframe commend that does all this hardwired

[jarod]

hi Joojaa,

thanks for your reply

I double checked too see if the setKeyframe command was responsible.
If you run the following script in a new maya scene, you'll find that
pCube1.translateX is still "settable". even without the use of the setKeyframe command

[codebox]
polyCube -w 1 -h 1 -d 1 -sx 1 -sy 1 -sz 1 -ax 0 1 0 -tx 1 -ch 1;
createNode parentConstraint;
connectAttr -f parentConstraint1.constraintTranslateX pCube1.translateX;

getAttr -se pCube1.translateX;[/codebox]

can you please elaborate on how to go about making my plugin as a constraint node? I'm still fairly new to this api stuff

thanks

jarod

[joojaa]

QUOTE(Jarod @ 07/10/07, 06:11 PM) [snapback]269485[/snapback]
pCube1.translateX is still "settable". even without the use of the setKeyframe command

Yes i know that, but the question is does it work the other way around? Apparently yes. So you could deduce that the tip setKey looks for. Ok so lets look into the manual how the output values differ in attributes

lets take a multiply divide which fails according to your theory if is connect this in
CODE
file -f -new;
polyCube -w 1 -h 1 -d 1 -sx 1 -sy 1 -sz 1 -ax 0 1 0 -tx 1 -ch 1;
move -r 0 3 0;
createNode multiplyDivide;
connectAttr -f multiplyDivide1.outputX pCube1.translateX;
getAttr -se pCube1.translateX;

// Result: 0 //
now this will report false for keyable. However set a key using setKeyframe pCube1; well surprise surprise puts a pair blend node gets inserted just like for the constraint, despite the fact that its not settable! This defuncts your theory that settable flag has any affect on this thing. Now this was maya 8.5 behaviour, lets test maya 6.0 for comparasion and identical behavior.

Now that its established that the type or settable flag of the connection have absolutely no bearing on the matter we need to test this with a simple enough node. So there must be some other reason!

Thing is as far as i can see it depends on whether you connect the attribute trough compound or not.

Compare (run in same scene):
CODE
polyCube -w 1 -h 1 -d 1 -sx 1 -sy 1 -sz 1 -ax 0 1 0 -tx 1 -ch 1;
createNode multiplyDivide;
connectAttr -f multiplyDivide2.output pCube2.translate;
getAttr -se pCube2.translateX;

Now this does not place blend nodes in! So whats the difference?

Well it so happens that i think i know what it is, i can deduce it by types of nodes created. Whats the difference? Well maya has difefrent float types and the triplet compounds come in 2 flavors linears and angulars, if its singular it does not matter but if not maya needs to know what it i like. See parent constraint has a compound:
CODE
constraintTranslate (ct)     double3    
  constraintTranslateX (ctx)     distance (double)    
  constraintTranslateY (cty)     distance (double)    
  constraintTranslateZ (ctz)     distance (double)

whereas
CODE
output (o)     float3
  outputX (ox)     float    
  outputY (oy)     float    
  outputZ (oz)     float

AND thats the difference now to test this theory. ill leave that to you.

[jarod]

Hi Joojaa...

thanks for the interesting ideas.

I'm not sure I completely followed your train of thought. Perhaps I didn't explain myself thoroughly enough. I will try to explain again (apologies for the repetition).

QUOTE(Joojaa @ 07/10/07, 08:17 AM) [snapback]269486[/snapback]
now this will report false for keyable. However set a key using setKeyframe pCube1; well surprise surprise puts a pair blend node gets inserted just like for the constraint, despite the fact that its not settable! This defuncts your theory that settable flag has any affect on this thing.

Just to clarify. After you run the setKeyframe command, getAttr -se pCube1.translateX; will return 1 again.

It is true that you have been able to setKeyframe on an attribute that is not "settable". However, prior to the setKeyframe command it was not possible to change pCube1.translateX in the channelbox without setting a keyframe.

I'm not really interested in the idiosyncrasies of the setkeyframe command, and when it chooses to add pairBlend nodes.

My central question is how can I change to settable parameter of an attribute?

I want to be able to connect the output of my node to, lets say, pCube1.myAttr. And still be able to change pCube1.myAttr in the channelbox without necessarily setting a key.

I'm aware of a few other nodes which function like this, so it should be possible. The nodes that I know of are, The parentConstraint node, the pairblend node and the character node.

here is an example of the character node in action

[codebox]

file -f -new;

polyCube -w 1 -h 1 -d 1 -sx 1 -sy 1 -sz 1 -ax 0 1 0 -tx 1 -ch 1;
addAttr -ln testAttr -at double |pCube1;
setAttr -e -keyable true |pCube1.testAttr;

createNode character;
connectAttr -f character1.linearValues[0] pCube1.testAttr;

print "\n";
getAttr -se pCube1.testAttr

[/codebox]

note that testAttr remains editable in the channelbox. also note that when you key testAttr, no pairBlend is created, instead an animcurve node is created an connected to character1.linearValues[0]

Does my question make more sense now?

any further comments idea?

(by the way, thanks for your time so far )

[joojaa]

Ok i misunderstood slightly, yes thats a different thing, i agree. That covers the pair blend part which is also very important in constraints (its the side that makes it usefull for keying). But the reasoning is there to help you think in maya terms. Node reference is a indispensable tool to the plug in programmer as HALF of what you can do is never disclosed in the api, but is implied in the node reference.

I dont have the API at hand at the moment but the way parent constraint works is totally different from the character set aor any set sets in essence ARE the attributes themselves. So the keying happens as usual jut the gui shows it a t a different place.

Nevertheless the result and action is simillar

I got a lead on this i must investigate before i disclose an further than this ithere IS a clue in the node reference. Anyway its not the keyable attribute that limits the input of the attribute per see, but rather the fact that it automatically gets rewritten with the original value even if you did type something (because theres no affected network upstream). Thing is the parent constraint node does connect in loop, so you can update values trough the parent matrix connection into the parent node. however pair blend does not...

So we have 3 different mechanisms at play here. Ive done this with sets but they are not suitable for your job.

PS: i was slightly wrong about the pair blend node tough, its because all constraints work on individual connections rather than the compounds that make the difference.

[roomie]

I don't mean to hijack this thread, I have made another post in the forum but I was curious Joojaa How I can make a custom constraint? Is there a MPxNode subclass that I can use as the basis of my constraint to inherit the constraint functionality such as changing the channels to blue, getting the pair blend functionality when a key is set as well as leaving the connected channels settable? I'd appreciate any help and again sorry for hijacking this thread!!!

tony

[joojaa]

All nodes have pair blend functionality, all you need to do is connect them by individual channel an not the compound! This has been discussed in the thread already so if you do:

CODE
file -f -new;
polyCube -w 1 -h 1 -d 1 -sx 1 -sy 1 -sz 1 -ax 0 1 0 -tx 1 -ch 1;
move -r 0 3 0;
createNode multiplyDivide;
connectAttr -f multiplyDivide1.outputX pCube1.translateX;
connectAttr -f multiplyDivide1.outputY pCube1.translateY;
connectAttr -f multiplyDivide1.outputZ pCube1.translateZ;
createNode multiplyDivide;
connectAttr -f multiplyDivide2.outputX pCube1.rotateX;
connectAttr -f multiplyDivide2.outputY pCube1.rotateY;
connectAttr -f multiplyDivide2.outputZ pCube1.rotateZ;

you can set the key and maya will put 2 pair blend nodes in place! (but if you want one node like you get from constraints input type must be right and come from one node)

[roomie]

Ok Jarod I have the answer to your Question,

What you need to do is in your node definition is override the MPxNode::isPassiveOutput method.

It accepts a MPlug &plug so you use that to check for your plug and return true. For example:

[codebox]bool yourNewNode::isPassiveOutput(const MPlug &plug) const{
if(plug.partialName(0, 0, 0, 0, 0, 1) == "translateX")
return true;
if(plug.partialName(0, 0, 0, 0, 0, 1) == "translateY")
return true;
if(plug.partialName(0, 0, 0, 0, 0, 1) == "translateZ")
return true;
if(plug.partialName(0, 0, 0, 0, 0, 1) == "rotateX")
return true;
if(plug.partialName(0, 0, 0, 0, 0, 1) == "rotateY")
return true;
if(plug.partialName(0, 0, 0, 0, 0, 1) == "rotateZ")
return true;

}
[/codebox]

That will keep your attributes settable! Now I need to figure out how to turn the colors of the connected channel boxes blue instead of yellow!!! Any ideas on that guys!?

tony

P.S. This was added in 8.5 so I don't think you can use this with your plugin if you intend for an earlier version compile...

[jarod]

Thanks tony!

I will try it out and let you know how I go!

Jarod

[david_corral]

Thanks roomie!!
It works perfect !!

Btw, I'm ussing it in this way:

if (plug.attribute()==aOutputTranslate)
    return true;
if (plug.attribute()==aOutputTranslateX)
        return true;
if (plug.attribute()==aOutputTranslateY)
        return true;
if (plug.attribute()==aOutputTranslateZ)
        return true;
if (plug.attribute()==aOutputRotate)
        return true;
if (plug.attribute()==aOutputRotateX)
        return true;
if (plug.attribute()==aOutputRotateY)
        return true;
if (plug.attribute()==aOutputRotateZ)
        return true;