path constraint trouble

jakerupert · April 26, 2010

I am still struggeling with the path constraint.

I have a car model sucessfully constrained to a path,

but strangly the modelbone is not moving along with it,

thereby causing the posesliders doing unwanted things.

Any ideas, what could keep the modelbone from going along happily with the model?

jakerupert · April 26, 2010

Guess I misunderstood something about the pathconstraint.

It is the modelbone that has to be constrained to the path....

jakerupert · April 26, 2010

Next difficulty:

I want to take an existing spline from a model as a path.

BUT

I cant select this spline with the picker ,neither can I see anything in the pulldownmenue.

What do I do wrong?

I even hide all the rest of the model ecxcept the certain spline.

Do I have to rebuild this spline as a path in the chorwindow?

That would be very tiresome, wouldn`it `?

robcat2075 · April 26, 2010

Try holding the SHIFT key when you do the picking.

Gerry · April 26, 2010

Can't you constrain to surface? Or is that the same thing you're trying to do?

johnl3d · April 27, 2010

you can follow any spline in a model by doing what Robert said ..constraint to path then shift pick the spline. That way you can model a custon path and use it in the chor also

jakerupert · April 27, 2010

Robcat, John thanks a lot.

That worked quite nicely, except:

I want the model to start moving from the other end of the spline and let it run it into the

contrary direction (Excuse my english, hope you understand)

How do I tell the model , where the starting point of the spline is and which direction to go?

(It`s awfull, how much you forget again of certain things, when you get ocupied with a different section of AM

for a longer time period, but I cannot jump that easily from modeling to rigging to animating etc.

because all these techniques take there certain time to get into them.)

The section I did least up to now - like many others here , I suppose - is animating, kind of sad,

since our favorite tool is called Animation Master!

I am eager to change that.

robcat2075 · April 27, 2010

How do I tell the model , where the starting point of the spline is and which direction to go?

The "Ease" property in the path constraint tells the object where to be on the path. If you leave it unset it automatically goes from 0 to 100%. You may want to key it to go from 100% to 0.

jakerupert · April 27, 2010

O.k., thank you, I presumed it must be as simple as that.

(Just out of curiosity:

Do you happen to know, how AM does decide, which is the beginning and end of the spline?

Probably which cp`s were createtd first during modeling I guess?

So if I would delete that spline, and model it from the other end, it would

reverse the path .( not that it makes sense to do it, if you have the ease channel)

Guess the best way to find out is to try...

so was merely talking to myself here..)

robcat2075 · April 27, 2010

Do you happen to know, how AM does decide, which is the beginning and end of the spline?
Probably which cp`s were createtd first during modeling I guess?

That's the way it works for simple splines we make with the path tool. I don't know how splines A:M creates( like after you lathe or extrude another spline) identify that except that it probably copies the arrangement of the original spline.

jakerupert · April 27, 2010

Not that it really matters, but it seems to me that in a model,

a spline as a path starts at the end of the modeling of each spline, but maybe its simply

accidental.

Here`s my experiment with the reversed easechannel. Succsess!

MolelandTrainTest2.mov

robcat2075 · April 27, 2010

Was this quicktime made on a Mac?

When I try to play it it says "This file can not be found"

John Bigboote · April 28, 2010

I believe A:M looks at the spline #'s and uses the lower # as the start point.

HomeSlice · April 28, 2010

When I try to view it, Quicktime opens, but no movie is displayed. What codec did you use?

jakerupert · April 28, 2010

Sorry, I copy and pasted a second clip into the first and didn`t save under a new name,

so I guess, it could`t find it`s original resources ( I could see it on my computer though, probably because it was

still linked somehow (so that irritated me), but also couldn`t see it on my computer at home,

the filesize, that didn`t change gave my the idea.)

So this one should work now, PC Sor3 codec....

MolelandTrainTest2.mov

jakerupert · April 28, 2010

Funny, on second looks, that seems somehow familiar:

Maybe like a more explicit ending of "North by Northwest" ?

jakerupert · April 30, 2010

Here`s continuing my humble efforts in mastering pathconstraints.

I understood the handeling of the easechannel now.

Next I tried to have a trucks trailer following behind with a lag,

so I made a dynamic constraint for the trailer,

but I only can see it working , when I drag the truck around

the path manually, not in my final render.

I wonder, is it because it`s not moving fast enough?

Second, the dynamic constraint lets the trailer move to the

outward direction of the circle.

I would have expected to be the other way round

Looks somehow wrong to me...

But may be a dynamic constraint is not the right way to go here?

Sorry here is the chor also

SemitestDynamic300410.mov

SemiPipes_DecalMaps.zip

SemiDynamictest.prj

SemiCarTestPath250410.cho

yoda64 · April 30, 2010

Without the linked chor, the projectfile is useless ...

jakerupert · April 30, 2010

Sorry, I submitted the chor also now

jakerupert · April 30, 2010

Like in the "moving background" thread with John`s help,

I managed to get a lag now

on the orient like constraint of the trailer bone.

Same problem at the start though,

also added dynamic constraint,

but not visible at that speed...

SemitestTranslateOrient300410.mov

yoda64 · April 30, 2010

I would suggest another bone orientation for your truck bone like the attached projectfile . Also using the truck bone for the path constraint instead of the modelbone .

test.zip

mtpeak2 · April 30, 2010

A dynamic constraint is not going to work, the trailer will fall through the ground plane. I'll see if I can get something working for you.

robcat2075 · May 1, 2010

A dynamic constraint is not going to work, the trailer will fall through the ground plane. I'll see if I can get something working for you.

A translate limits constraint could stop that

yoda64 · May 1, 2010

A dynamic constraint is not going to work, the trailer will fall through the ground plane. I'll see if I can get something working for you.

It can work , look at my projectfile .....

mtpeak2 · May 1, 2010

Sorry Steffen, but this is what I get when rendering your project. (see attached)

Robert, a translate limit is not going to help from keeping it from rotating through the ground plane. If you mean an euler limit, that probably is not going to help either. The dynamic constraint, I think, will override the limit or the limit will cause issues with the dynamics. I don't even think turning ON collision will help.

I have it working with path constraints, but it's not entirely accurate. To be accurate, you will multiple paths (actually, you would need a separate path for each tire), but you could get away with just 2 paths, one for the truck and one for the trailer (the trailer will not follow in the same path as the truck when turning, it will take the shortest route to the pivot point of the trailer hitch).

Steffens_Chor.mov