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TSpyrison
12-08-2003, 08:54 AM
Ok..
Another question..

Is there a way to slow the velocity of an object over the course of its motion path?
Ive got an object that travels in an oval path, which was derived from a curve in modeler. Now, the motion path has a lot of keyframes in order to keep the wheels of the object on the track..

My problem is, that I need to slow the object to a stop over the last 5 or 6 keyframes. Is there a way to control the velocity of an object without screwing up the positional keyframes?

TSpyrison
12-09-2003, 08:00 PM
Anyone????

:confused:

Zafar Iqbal
12-10-2003, 03:25 AM
You would have to mess with the keyframes - try scaling the range of keyframes and then do some tweeking if needed.

digimice
12-10-2003, 04:03 AM
hi,

you can use Motionmixer for this. Just create an actor and a motion and use the speedwarp-curve to control the velocity. So you can change the speed of your object without changing the motionpath.

cheers alex

glassefx
12-10-2003, 10:47 AM
Thats kinda fuzzy but,

Could you just not make that object a child of a null and the null has the slow-down you want?

Make sense?

I covered this anwsering a question before in the last couple of days. Do a search under my alias. It's pretty recent.

I think its called "dynamic parenting question" or somthin'.

TSpyrison
12-10-2003, 12:54 PM
Originally posted by glassefx
Thats kinda fuzzy but,

Could you just not make that object a child of a null and the null has the slow-down you want?

Make sense?

I covered this anwsering a question before in the last couple of days. Do a search under my alias. It's pretty recent.

I think its called "dynamic parenting question" or somthin'.
Woudn't the null have to have the same motion path as the object that I want to have slow down in the first place?

I mean, if I could do it with the null, why couldn't I do it with the main object to begin with? or am i missing something basic...

:confused:

glassefx
12-10-2003, 04:22 PM
Originally posted by TSpyrison
Woudn't the null have to have the same motion path as the object that I want to have slow down in the first place?

I mean, if I could do it with the null, why couldn't I do it with the main object to begin with? or am i missing something basic...

:confused:

hum, I'll try to explain the principal and the details of parenting..

hope this helps. here goes.

A parent will dicate the movment of a child but the childs movment will be there too just added.

not good..

imagine growing up. Your parents basically dictated your actions to most extents but you moved the way you wanted to.

say in LW an object had the normal X,Y,Z,H,P,B,and Scale x,y,z - but if you made a key on frame 5 all of the channels recieved a key on five also... Thats the way old lw workd... to get multiple motions on a object without having a motion graph that looked like it was on crack you had to do it in parenting.. to get three seperate motion channels (they still all had a key for every channel) you had to parent a null to another to another... then you could put a motion on each null and only the BOTTOM-MOST child would get ALL of the combined motions of all its Parents but still can have its own motions...

see what i am trying to convey?

like this heiarchy..

LAUNCH PLATFORM
SHIP ROTATIONS
SHIP MOVEMENTS
SHIP SCALES
SHIP (the main child - all above are parents)

so Launch platform is the bottommost, you move it and they all move.. but you can still move them all separately.

ship rotations parent is launch platform
ship movments parent is ship rotations
ship scales parent is ship movments
ship parent is ship scales.

whew!

open an empty scene and throw in 5 nulls and replicate this and key some movments and see...

it's old-school, but a basic principal that is seemingly overlooked quite a bit these days.

let me know if you need help, I will make a scene file for you to pull apart...

peace

TSpyrison
12-10-2003, 08:02 PM
I understand about parenting, but with this particular setup, I donít understand how that would help me slow or stop the "engine". (the whole thing is a toy train, going around a toy track..)

Iím uploading the basic scene file so you can get an idea of whatís going on here. I need to be able to slow the engine down to a stop. (the wheels turn with the help of Relativity, but thatís not setup in this file)

The whole reason im not using the graph editor, is if i make adjustments there, it throws the train off the tracks. (the motion path was created from the same spline the the track was extruded from)

Ugh.

:D

glassefx
12-11-2003, 10:35 AM
It can be done with patenting and applying the motion of the train in an inverted fashion to the trains parent null at some point on the time line. I explained it in a prior post last-night. Do a search under my alias if yas want. The easiest way to do what your wanting is to derive the model from the motion curve instead of deriving the motion curve from the model. There are TONS of work-arounds when dealing with basic motions though so I'll look tonight at home and will try to work something out for you. If not I will ty to modify your exsisting curve.

see, the further the points are apart on your curve the faster the motions will be. I have a few macro's to derive a accleration and deacceleration. I will tinker and share.
even if you did apply the curves motion in an inverted fashion to a parent null (of train) you still would be moving points around either in modeler or the graph editor.