Add Feature in Cuda to NVidia Particle Example

I want to add a feature to the NVidia Particle example included in the SDK. /Developer/NVIDIA/CUDA-8.0/samples/5_Simulations/particles The feature is to track the contacts between particles between subsequent time steps. In the sample contacts are not tracked. I would like to keep track of the contacts and incrementally contact the normal force. In the collideSpheres function in [login to view URL] the following line: // tangential shear force force += [login to view URL]*tanVel; would be replaced by something like: delta.x += varis->delta_t*vrs.x; delta.y += varis->delta_t*vrs.y; delta.z += varis->delta_t*vrs.z; shear.x = delta.x * varis->kc; shear.y = delta.y * varis->kc; shear.z = delta.z * varis->kc; double friction_force = [login to view URL](); double max_friction_force = friction*varis->kc*penet; if (friction_force > max_friction_force) { delta.x *= max_friction_force/friction_force; delta.y *= max_friction_force/friction_force; delta.z *= max_friction_force/friction_force; shear.x = delta.x * varis->kc; shear.y = delta.y * varis->kc; shear.z = delta.z * varis->kc; } where the delta.x , y, z is tracked for each contact between iterations. Looking for someone with good CUDA skills that can implement this properly.