connecting to curve control points

#1

hey! I dont know if this has been asked a lot before (I have trouble searching )…

Im trying to connect values to the control points of a curve. I can do it no problem in an empty scene with my usual settings, but when I try it using a file with a character supplied by a client, maya wont let me make the connection. it kind of makes it (it shows up highlighted in connection ed but the connection lines in hypershade dont always show up). hovering over the connection it says “UnitConversion##” instead of the normal attributes. I just dont know how to turn this automatic conversion or whatever it is maya is trying to do.
I usually have maya units set to cm and this new file is m, but is that the problem? can I turn off the conversion (where??) or what do I do??

wish they would stop second guessing units and just leave the data alone.

Im on 2009 for this one.

thanks to anyone who can help!

edit:
I figured maybe I could link through my own unitconversion node (with just a factor of 1) to stop maya from doing it, but I cant even get those nodes to show up in hypershade or graph. is this a 2009 thing or am I missing some newbie option that hides them, similar to aux nodes in the outliner?

edit2:
turns out I CAN use locator worldPositionseven in this file, but not the way I usually do with transform.worldMatrix -> vectorProduct -> controlPoint. still want to know why =|

#2

To see unit conversion node, make ‘show auxiliary nodes’ activated in >>show<< menu of hypergraph

#3

Do you mean you want to connect some objects’ transforms to drive the CVs of a curve?

The way I do it is to connect the worldMatrix attribute of a transform node to the inputMatrix attribute of a decomposeMatrix node and then the outputTranslate of that to the controlPoints[0], controlPoints[1], etc. attribute on the curve’s shape node. It doesn’t introduce any unitConversion nodes.

For example:
group1.worldMatrix[0] -> decomposeMatrix1.inputMatrix
decomposeMatrix1.outputTranslate -> curveShape1.controlPoints[0]

Oh and to make it more bulletproof, lock and hide the translate, rotate and scale attributes on the curve and turn off inheritsTransform on it too.

:¬)

#4

Hi thanks for the reply!

yeah thats what Im trying to do. I think its tidier just using transforms for points and then adding nodes just when I need world coords. (instead of using just locators all over)

Is that decomposeMatrix a plugin node? maya doesnt recognize it…

and do you have any idea why maya wont let me use vectorProduct for the same thing anymore?? is using it some taboo I was unaware of?

#5

The decomposeMatrix node plugin should come with maya but I don’t think it’s loaded by default. Check your plugin manager and auto-load it. 'tis a very handy node to have.
:¬)

#6

yeah the decompose matrix should do the trick . but anyway a simple unit conversion shouldnt give any trouble you can easly bypass it handling the data that comes before the node or after

#7

Hi there, I was about to script something like this, but I get stuck when I need to plug each locator to each cv of the curve… as you can see I did put [6] but of course is wrong… there is something missing or wrong in that specific for loop.
Here is the code:

//creating curve guide
string $createCurveGuide = curve -d 1 -p 0 0 0 -p 0 30 0 -k 0 -k 1 -n ("Spline" + "_crv");
string $curveGuide[] = rebuildCurve -ch 1 -rpo 1 -rt 0 -end 1 -kr 0 -kcp 0 -kep 1 -kt 0 -s 5 -d 3 -tol 0.01 $createCurveGuide;
string $curveGuideShape[] = listRelatives -s $curveGuide[0] ;

//STORE SOME VARIABLES–
string $selCurve[] = $curveGuide ;
int $noSelCurve = size($selCurve);

//THIS IS THE FOR LOOP FOR CREATING JOINT CHAIN ON SELECTED CURVES—
for ($i=0;$i<($noSelCurve);$i++)
{
select -r ($selCurve[$i] + “.cv[li]”);
[/li] string $cvPos[] = ls -sl -flatten;

//THIS LOOP CREATES A Locator FOR EACH CV IN THE CURVE---

    string $oldLoc = "";
    for ($cv in $cvPos)
    {
    string $createLocPos[] = ` spaceLocator `;    
    string $createSplineLocName[] = ` js_hashRename ("_Spline" + "_POS_##") `;
    string $decompMatrix = ` createNode decomposeMatrix -n ("_decMat") `;
    
    float $xyz[] = ` xform -a -ws -q -t $cv `;
    xform -a -ws -t $xyz[0] $xyz[1] $xyz[2] $createSplineLocName[0];
    
    // connecting each loc worldspace to each cv in curve, in order to follow
            string $locMatrix[] = $createSplineLocName ;
            int $noLocMatrix = `size($locMatrix)`;
            
            for ($i=0;$i&lt;($noLocMatrix);$i++)
            {
               connectAttr -f ($createSplineLocName[$i] + ".worldMatrix[0]") ($decompMatrix + ".inputMatrix") ;
               connectAttr -f ($decompMatrix + ".outputTranslate") ($curveGuideShape[0] + ".controlPoints[6]");
            }
            
        if ($oldLoc != "")
        {
            parent $createSplineLocName[0] $oldLoc;
        }
        $oldLoc = $createSplineLocName[0];
    }
}
#8

Thanks to giordi, sorted.

#9

Hey just out of interest, why do this over skinning or clustering a curve? Just wondering what the benefits are.

#10

The main benefit is a cleaner looking connection graph in the hypergraph. With clusters you have groupParts, groupIDs, the cluster and the clusterHandle and the whole thing graphs out looking like a staircase as you’re looking at a full construction history on the curve. However if you use decomposeMatrix you have a much clearer relationship between the curve and what’s driving it.
:¬)

#11

totally agree. Also i dont see why i have to use a deformer like clusters when cna be easily done with cleaner way .

#12

Hi guys, I’ve got these warnings here :

// Warning: file: Cannot add the following items to the set since the set has restrictions on membership: charNameSpline_crv.ep[4] // 
// Warning: file:  None of the items can be added to the set //

Which are slowing down my script a lot… any ideas ?
Cheers

#13

I guess not :).

#14

It’s hard to know where these warnings are coming from without any context. Could you elaborate?
:¬)

#15

Yes sure.

Basically here’s a chunk of code:

for ($counter = 1; $counter < ($NumberOfCV - 1); $counter++) { select -r ($ii + ".ep[" + $x + "] "); string $TempCluster_[] = `cluster -n TempCluster`; float $clusterxyz[] = `xform -q -rp $TempCluster_[1]`; float $jointX = $clusterxyz[0]; float $jointY = $clusterxyz[1]; float $jointZ = $clusterxyz[2];

If you replace .ep with .cv I don’t get those warnings anymore, there must be something related to the clusters or the type of selections…
Hope it’s clearer …

#16

Yeah, I was going to say that you should be using CVs instead of EPs.
:¬)

#17

I know but the number and the position of the objects that I get is not what I want with the cv…

#18

So do you want to build a curve from the position of some transforms but also have the curve fit those nodes?

If so, you might have some luck by building a degree 1 curve from the transforms, connecting them to the CVs (through a decomposeMatrix for example) and then doing a fitBspline on it.

:¬)

#19

I recently came across the Point On Curve Deformer. It may be a good alternative for you. It only creates two nodes, a locator (which you could use, or replace the shape node of the locator with a curve shape if that’s preferred), and one other node called ‘leastSquaresModifier’. Ok, there’s another hidden object that is created, because this is a deformer, the original shape is stored and becomes an intermediate object. The great thing about it is that when you move the locator, the curve always ‘sticks’ to it, unlike the results when moving a CV.

[ol]
[li]Create a curve.[/li][li]Select an EP (not a CV). Or, select all of your EPs, the deformer will create one locator for each EP.[/li][li]Go to Animation>Create Deformers>Point On Curve.[/li][li]Select the newly created Locator(s) and Modify>Center Pivot. (The pivot is at the origin by default)[/li][/ol]

#20

Hello Mats, Brad and everyone

Just a quick tip:

My first try , when I wanted to simplify my network( apart from creating asset container )was to use the locator shape worldPosition attribute. If the driven curve is parented to a group with inherits transform off and don’t move it’s fine but ( a fool proof ) more solid approach is to include the parent transform with a pointMatrixMult node


The next step was to compact these point/matrix multiplication into a python node(a really simple exercice, but fun nonetheless).

Why duplicating node to retrieve a position in world space? The last step was to use a regular transform worldMatrix as an incoming information.