After the object has been created we start simulation loop. First we will accumulate forces which act on all particles of the soft body object. As it was mentioned before - we consider three main types of forces. Two standard SM forces - gravity and linear spring force are applied. Then third, special - pressure force is computed for every body face and distributed over particles. Let us go trough implementation of all the forces, where special effort will be made to describe an implementation of pressure force calculation subroutine.