Calculate the Velocity at which an object collides?

Game Engine Game Engine Support and Discussion
1

Hi, I am a total noob at python, so how can I find out the velocity at which an object is moving when it hits something? I would like to use this in multiple things such as fall damage, crashing vehicles, dropping an object from a height etc.

Example of what I would like to do:

  • Have a python script edit a property float that tells us what speed the object is moving at.
  • On collision with another object, compare the velocity to certain outcomes (if the velocity is < 2m/s do nothing, if <5>2 take damage, if >5 die)

What is the easiest way to do this?

Thanks :slight_smile:

2

This script by Social is good for what you want - here is a link to the thread:

http://blenderartists.org/forum/archive/index.php/t-170519.html

3

what you have to do is compare the old velocity with the current velocity.

the old velocity not exist as default property , you have to do it your self:

just be aware to the order , first compare , then store :


def main(cont):
    own = cont.owner
    if not "init" in own :
        own["init"] = 1
        own["oldVel"] = own.localLinearVelocity.copy()
        
    #comparison
    impactVector = own.localLinearVelocity - own["oldVel"]
    impactSpeed = impactVector.magnitude
    if impactSpeed &gt; 5.0 : 
        print("die for the impact -&gt;", impactSpeed )
    
    #store the current velocity
    own["oldVel"] = own.localLinearVelocity.copy()

PS:
not should be so hard to implement, this is my impactSensor custom: (that require of course other code)


import xxx
import bge


        
def m(cont):
    own=cont.owner
    


    if not "init" in own:
        own["init"] = 1
        own["impact"] = bge.xxx.createImpactSensor(own)
        
    impact = own["impact"]
    if impact.magnitude &gt; 5:
        #die()
        own.endObject()