A method of calculating the light scattering of irregularly shaped particles by a ray-tracing program is presented together with a new procedure for the three-dimensional reconstruction of the particle shapes. The simulation is based on geometrical optics. The paths of rays are calculated until they encounter specific end conditions (e.g., detection by a transducer). The result of the calculation is the scattering function of the particle in any arbitrary orientation. The results of the program have been successfully compared with those of the Mie theory with microwave-scattering experiments and light-scattering measurements involving individual, electrodynamically suspended particles.