This flag is modeled by using essentially a particle system with a set of predefined springs according to Hooke's law for Damped Spring between pairs of particles. The cloth is modeled as a regular 2D grid where the grid nodes correspond to particles. The cloth can be animated by moving the particles which will deform the regular grid. In this applet a "Wind force" is added to the Particle System to obtain animation. Springs are not created at random between the cloth particles, but a certain structure is used to mimic cloth properties. Structural springs are created between each pair of horizontal and vertical particle neighbours. The purpose of structural springs is to resist stretching and compression of the cloth. Shearing springs are used to make sure that the cloth does not shear. This assures that a square peace of cloth remains square. Shearing springs are created between diagonal neighbour particles. Bending springs are inserted to make that the cloth will not have sharp ridges when it is folded. These springs are created along the horizontal and vertical grid lines, between every second particle.