[Closed] speed along path controller

Put a script at objects path controlers percent value:

 
-- velocity in meters/sec
-- v is box height
-- thePath is the path :) 
-- this gives proper position at path when system unit is default inch and
-- display unit is meters, so 3.5m height gives 3.5 m/s
v * S / (curveLength thePath)

Thanks Decon, I’ve put there script already, I am able to change constant speed on the object… when I set speet to constant 60, 80, whatever, it goes and changes percentage. Now I would like to improve it with dynamic speed. I need somehow to call the current position percentage and add to it the speed formula, guess then I can get the real acceleration… currently I’am getting Illegal self-reference error.

cheers
filip

Hey, could you post your file or explain how you achieved it so ramping the value down doesn’t cause the object to reverse? Decon’s solution doesn’t seem to be working for me. Thank you!

You are going to have to add up the velocity per frame each time.

So…

 v=calc velocity as shown.
 pathPercent+=v
 

You will need to do this per frame so you need to work out the velocity based on your current frame rate or use ticks.

Thanks a lot for reply PEN,
what I finally did is the summary of all velocity values to the current frame, divided by current frame value.

“LEN = curveLength self.pos.controller.path
Trav = self.modifiers[#CarCTRL].Test_spinners.dist_spnr*1000

T = currenttime
sum = 0

for cx = 1 to T do
(
at time cx
sum = sum + ( self.modifiers[#CarCTRL].Test_spinners.speed_spnr / T)
)
sum

PERCi = sum/3.6*S/LEN
D = Trav/LEN
PERC = PERCi+D”

Currently have another problem, I added wheel rotation derived from the path length, path percent and wheel radius. The problem is, that the wheels are turning sometimes inverse. I think, that the start rotation direction +/- of the wheels depends on the start car position/rotation. Do you know, how to solve this problem?

“LEN = curveLength (for x in refs.dependents(this) where isValidNode x collect x)[1].parent.pos.controller.path
PERC = (for x in refs.dependents(this) where isValidNode x collect x)[1].parent.pos.controller.Percent
RAD = (for x in refs.dependents(this) where isValidNode x collect x)[1].parent.modifiers[#CarCTRL].wheel_spnr
rot = (PERC/1000*LEN)/(RAD)”

Thanks
Filip

huh, it took me a while to grasp this !

 
ct = currenttime
dis = 0
-- next, for every frame let's calculate
-- the velocity and add them up
for i = 1 to ct do (
 hoo = at time i $Box01.height
 dis = dis + hoo
)

Thanks Paul and Filip

I already spent a whole day trying to figure this out, but it keeps on reversing whenever I the box height value is lowered…

theTime = currentTime
 velo = boxHeight * S / (curveLength myPath)
 myVal02 = 0
 
 for o = 1 to theTime do
 (
 	tempVal = at time o velo
 	myVal02 = myVal02 += tempVal
 )
 
 myVal02

shouldn’t val02 always be increasing in value instead of decreasing when the box height is lowered?

Hi, I’ve finnaly used attribute holder instead of box height.
here is my test scene
Open the scene, pick the car, run “add car path v1.5.ms” pick the path, then select front wheels and run “add wheel steering v1.5.ms” In modifier of the car is attribute holder where you can change wheel radius, distance of tracks, speed of the car and travelled distance on path.

known bug: wheel rotation is sometimes inverse:(

cheers
filip

jack, if it’s still fuzzy, take a look at this :

http://www.deconstudio.net/down/Adjust_speed_with_box_height_03.zip