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contactCallbackFunction

The contact callback function

Child scripts, or customization scripts can include a contact callback function, which is one of many system callback functions. When present, and the physics engine detected a collision between two respondable shapes, then the contact callback function will be called with appropriate arguments, allowing the user to customize the handling of contacts. The contact callback function might be called very often, sometimes more than several hundred times per simulation step (remember also that by default, the physics engine will be called 10 times for one simulation step). For that reason, keep things simple, in order to avoid slowing down the simulation.

Following represents a typical contact callback function:

function sysCall_contactCallback(inData)
    -- Will objects with inData.handle1 and inData.handle2 respond to dynamic collision?
    local retData={}
    retData.ignoreContact=false -- handle contact here
    retData.collisionResponse=true -- shapes will collide

    if inData.engine==sim.physics_bullet then
        retData.bullet={}
        retData.bullet.friction=0
        retData.bullet.restitution=0
    end

    if inData.engine==sim.physics_ode then
        retData.ode={}
        retData.ode.maxContacts=16
        retData.ode.mu=0
        retData.ode.mu2=0
        retData.ode.bounce=0
        retData.ode.bounceVel=0
        retData.ode.softCfm=0
        retData.ode.softErp=0
        retData.ode.motion1=0
        retData.ode.motion2=0
        retData.ode.motionN=0
        retData.ode.slip1=0
        retData.ode.slip2=0
        retData.ode.fDir1={0,0,0}
        local mode=1 -- bit-coded. See below
        -- 1=dContactMu2
        -- 2=dContactFDir1
        -- 4=dContactBounce
        -- 8=dContactSoftERP
        -- 16=dContactSoftCFM
        -- 32=dContactMotion1
        -- 64=dContactMotion2
        -- 128=dContactSlip1
        -- 256=dContactSlip2
        -- 512=dContactApprox1_1
        -- 1024=dContactApprox1_2
        -- 2048=dContactApprox1
        retData.ode.contactMode=mode
    end

    if inData.engine==sim.physics_vortex then
    end

    if inData.engine==sim.physics_newton then
        retData.newton={}
        retData.newton.staticFriction=0
        retData.newton.kineticFriction=0
        retData.newton.restitution=0
    end

    return(retData)
end

In Python, a contact callback function can only be implemented via a non-threaded script, and it should be explicitly activated with a luaExec command:

#python
#luaExec additionalFuncs={'sysCall_contactCallback'}

def sysCall_contactCallback(inData):
    pass

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