ATMOSPHERIC EFFECTS SIMULATION

摘要

The motion of particles such as snow is simulated in a computer generated image which represents the appearance from a predetermined viewing point of a three-dimensional worldspace through which the particles move. A threedimensional model is defined which is made up from a regular array of abutting cubes of predetermined dimension. An object is defined which dimensions correspodond to the dimensions of each cube, the object having characteristics such that it represents the motion of particles through the volume which it occupies. The three-dimensional model made up of the array of cubes is notionally positioned in worldspace such that the viewing point is located within a region of the model selected such that the field of view of particles from the viewing point is always within the model. As the viewing point travels through worldspace it is translated in steps with the magnitude of each step corresponding to the length of any one side of the cubes. The model is moved in worldspace so as to maintain the viewing point within the selected region of the model. The image which is generated includes the model in which the object representing the moving particles occupies each of the cubes. The visibility of the cubes is faded out with distance from the viewing point so as to conceal the boundaries of the model. The model is positioned relative to the viewing point such that a notional point on a line drawn through the viewing point in a predetermined direction relative to the viewing point motion is always within a predetermined central region of the model. The distance between the notional point and the viewing point is a function of the speed of movement of the viewing point.