# Local Velocity

How does one find the local velocity of an object? I’m trying to make a movement script that limits objects to a maximum speed.

``````
import math
#get velocity ([0] = x, [1] = y, [2] = z), so if you want just x-velocity type owner.getVelocity()[0]
speed=owner.getVelocity()
#calculate total speed (x+y+z velocity)
speedtotal=math.sqrt(math.pow(speed[0],2)+math.pow(speed[1],2)+math.pow(speed[2],2))

``````

Thanks, but I don’t think that’s it. I searched the forum and found some code that I converted to a function. It gives velocity using the local coordinate system and is fairly accurate.

``````def getLocalVelocity(obj): #created by Ridiculous of BlenderArtists.org (as far as I know) with minor modifications by me
Vel = obj.getLinearVelocity()
Ori = obj.getOrientation()

Vel = [
[Vel[0], 0.0, 0.0],
[0.0, Vel[1], 0.0],
[0.0, 0.0, Vel[2]]
]

LocVel = [] #same as "LocVel = MultMatrix (Vel, Ori)"
for r in range(3):
row = []
for c in range(3):
row.append(Vel[r][0]*Ori[0][c]+Vel[r][1]*Ori[1][c]+Vel[r][2]*Ori[2][c])
LocVel.append(row)

# I'm getting the sum of the values in the columns to get the
# local velocity. It works, but it might be wrong because it's not
# like getting the magnitude. As you may know, magnitude is always
# positive, but I need negative and positive values, so I'm just using
# the sum
LVelX = LocVel[0][0] + LocVel[1][0] + LocVel[2][0]
LVelY = LocVel[0][1] + LocVel[1][1] + LocVel[2][1]
LVelZ = LocVel[0][2] + LocVel[1][2] + LocVel[2][2]

return [LVelX, LVelY, LVelZ]

### I added this code to test it
cont=GameLogic.getCurrentController()
own = cont.getOwner()

print getLocalVelocity(own)
``````

The topic was here: http://blenderartists.org/forum/showthread.php?t=49213 post #11

Oops, sorry… I somehow missed that local-word and thought you only want to know the velocity of the object. Looks like it gets much more complicated if you want local velocity.