| 摘要 |
<p>Input data defines the address (X,Y), and an input colour (RGB) and depth (Z) for a picture element (pixel) within a stored image. In order to perform hidden-surface removal (HSR), current depth values are stored for each pixel and compared with the input depth value to determine whether or not input data should be written to define a new colour and depth for the pixel at (X,Y). The colour and depth values are stored in a colour RAM (9) and z-RAM (64). To obtain a speed advantage when modifying a series of consecutive pixels of one row of the RAMS, the current depth values are read and compared in advance for each pixel, during the writing period of one or more preceding pixels. The apparatus comprises a control and arithmetic unit (42), and a HSR control circuit (60) in addition to the colour RAM (9) and z-RAM (64). The apparatus uses readily available video DRAM chips to provide a z-RAM with two data ports (62,66). The apparatus may form part of an electronic graphics system.</p> |
