detect node(s) on softbody

[passerby1023]

hi there,

I created a btSoftBody in my btSoftRigidDynamicsWorld ,
and i want to simulate a simple touch behavior with addForce(const btVector3& force,int node) method by giving an Absolute position and direction only , but addForce method needs second parameter 'node' . Is there a way to detect the node(s) only giving the position and direcition by user?
Any advice would be greatly appreciated.

[passerby1023]

I think i should simplify my question

we can get the position of nodes by their node structure member ,
but when I only have position , can I determine is there are any nodes close to that position?