Abstract: A computer graphics apparatus comprises a modelling package and a rendering package. The modelling package outputs data representative of the definition of a scene to be represented graphically. The rendering package receives data representative of the scene to be represented graphically, and converts that data into rasterised image data. Preprocessing apparatus is provided to arrange the data defining the scene in a manner which can be more easily processed by the rendering package. The preprocessing apparatus partitions the scene by means of partition planes in directions selected from three mutually perpendicular directions. The planes are positioned so as to eliminate as much empty space as possible, to cause as little division of geometry of the scene as possible, and to deliver sections of the scene which contain no more than a particular level of detail.

Abstract: In an apparatus and method for performing perspectively correct interpolation of texture coordinates in computer graphics, an incremental interpolation technique is used to calculate pixel values along a display line from an associated texture map. In order to evaluate divisions within the hyperbolic equations relating the texture coordinates to pixel position, the incremental technique performs a log subtraction in which the log of the fractional part of a number is looked-up, while the exponent part of the number is tracked separately. The differential of each texture coordinate is tracked. Further, the incremental technique is arranged so as to render the pixels either from left to right or from right to left depending upon which edge of the polygon being rendered is closer to the viewer and hence at which of the polygon edges accumulated errors will be most visible.