with(oGearBase)
{
    processed = false
}

// 1. compute torque of each "input"
with(oGearInput)
{
    torque = (vel_target - vel)/10
}

// 2. sum the torques
//with(oGearInput)
for(i=0; i<instance_number(oGearInput); i+=1)
{
    ins = instance_find(oGearInput, i)
    if(!ins.processed) {
        // browse all gears of the current network
        // and compute the torque sum
        torque_sum = 0

        ds_stack_clear(stack)
        ds_list_clear(list)

        ds_stack_push(stack, ins)

        while(!ds_stack_empty(stack)) {
            top = ds_stack_top(stack)
            ds_stack_pop(stack)

            if(!top.processed) {
                ds_list_add(list, top)
                top.processed = true
                torque_sum += top.vel

                if(top.gear_r != noone) { ds_stack_push(stack, top.gear_r) }
                if(top.gear_l != noone) { ds_stack_push(stack, top.gear_l) }
                if(top.gear_u != noone) { ds_stack_push(stack, top.gear_u) }
                if(top.gear_d != noone) { ds_stack_push(stack, top.gear_d) }
            }
        }

        // set the new torque
        roger = min(-1000, max(torque_sum, 1000))
        for(n=0; n<ds_list_size(list); n+=1) {
            ii = ds_list_find_value(list, n)
            ii.torque += roger
        }
    }
}


with(oGearBase)
{
    acc = torque
}