Nurbs Curves... Arrrrrrgggghh!

[naughty]

I don't care if NURBS curves are better than bezier curves, they are still an utter pain in the ass to work with...

I have created a letter t using the text function. it is a lovely 2 degree curve with some smooth CVs (not connected to the curve) and some magical CVs that are hard and connected to the curve creating lovely HARD corners.

how do I query a CV and find out if it is hard or not? I NEED TO KNOW!!!!

the hardenPointCurve command is a joke and seems to only produce the result:

// Error: line 1: No object was specified to query //

when I try to query the multiplicity with something like:

hardenPointCurve -q -m curve1.cv[4];

please help me!! I need to be able to tell the difference between these two types of CV.. there must be a way as they are so radically different in how they are attached to and affect their curves... I've tried querying the .weights attribute and they all come back as 1 so that's no help...

also, not strictly related to the above query, but how the hell do you manually produce a curve (using the CV or EP curve tool) that is the same as a curve produced using the text function? is it even possible using a single curve AS THE TEXT FUNCTION produces...? It seems pretty dumb if you can't produce curves manually that you can produce using textCurves (or elsewhere and import) yet still edit..?

:nathaN

[joojaa]

Ahh you have befallen the most devious idea of maya command design. Wich makes you think you can do this there are about as many instances of possibility for this confusion as theres nodes in maya that have their own commands.

Commands dont usualy work on arbitrary data. But rather are sppecialized to work on the nodes they spawn. There are literery hundreds uppon hundreds on answers on the same question made on this forum over the ages.

Se hardenPoint only works on nodes it creates. So inorder for you to querry harden point you can just ask for is this ocmponent hard. You must ask a harden point node. Wich defeats your purpose!

Now theres some general nodeal querryers that do know how to obtain this data data getAttr being often the unviersal querrier since it indeed can querry allmost everything maya has to offer.

Im not if front of maya right now so i cant tell you what the real way to do this is but wha your after is the pointweight of your curve. BUt i can tell you how you CAN know what t do, first you open the node reference for nurbs curves, look what array atrubute contains the weighting info then querry taht atribute of the curve SHAPE.

PS. making a cubuc curve with each 4 point weigtherd by 3 makes for a bezier curve.

[naughty]

I've already read every previous post containing the words "CV and HARDNESS"! and NONE of them sufficiently answered my questions, the only thing I learned is that you can edit the weight of a CV but this doesn't seem to actually be the same thing as a HARD CV at all, and once you move a CV its weight resets back to 1..?!?

anyway... I've already looked through the node reference for nurbsCurve and there is NO mention of weights.. if you follow this ref up to curveShape and then up to controlPoint you do find an attribute called weights but every CV seems to have the default weight of 1... setting this to other values DOES NOT make the CV stick to the curve as a hard corner, and once you move the CV, it resets back..!?!

there must be an easy way to do or query this...?!

[joojaa]

ill look into it... On the otherhand the knotting is possible to do via api so its not seen as weighting.

[joojaa]

Okay what you have done is a mult i knot wich is a bit digfferent from weight. But yes it seems like the hardenPointCurve acts a bit iffy.

Anyway a nurbs curve is actualy a combination of cvs and edit points.

So you can use curve info to figure out what cv is hard Note multiplicity acts on the ep not teh cv but its easy to figur3e out what cv is vvhat knot. This si justt one way theres a few others you can use.

heres a very dirty way of getting all the hard KNOTS, im way too tired to optimize and conevrt it to cvs becaus eis not realy the cv tahts hard but the correspondence is calculabele... but its beyond my bedtime... Also tythis asumes 3rd degree curve.

proc testHardness3degree(string $shape){
int $hard[];
$info=createNode curveInfo;
connectAttr -f ($shape+".worldSpace[0]") ($info+".inputCurve");
$num=getAttr("-s","curveInfo1.kn");
$knots=getAttr ($info+".kn[0:"+($num-1)+"]");
$hit=0;
$last=-1;
for ($knot in $knots){
if ($knot==$last) $hit++;
else{
if ($hit>1)
$hard[size($hard)]=($knot-1);
$hit=0;
}
$last=$knot;
}
if ($hit>1)
$hard[size($hard)]=($knot);
print $hard;
}

[naughty]

thanks for your input joojaa but unfortunately I don't really understand what a knot is and how it relates to CVs...

I tried your proc on a 3 degree curve that has 16 CVs: 0, 3, 6, 9, 12 and 15 are hard. getHardness returns: 0 1 2 3 4 5.

does that mean (knot*degree) = cv ?

if I multiply the hard knot indexes by 3, I get the index number for the hard CV.. is it as simple as this? or is it just coincidence this time?

I'll do a few more tests....

[joojaa]

Yes your curve emulates a bezier curve since every 4th point is hard. Wich is not very supprising if it was importted form a source thet uses beziers.

You neeed to step trough those points to se wich hard ones you miss. So every time theres a space in the knotting theres thatmany nonaffiliated points in addition to the knot numbering Take a look at how hardness affects your editpoints wich correspond to the knottinng!