Method and apparatus for determining visible surfaces

Abstract

A system for rendering a three-dimensional scene by determining each visible surface of geometric shapes for a sequence of frames. For a selected frame, a working frame buffer is initialized by copying background data maintained in a background frame buffer to the working frame buffer. A working Z buffer is initialized by copying background depth data of the background Z buffer to the working Z buffer. The background data is represented by a bitmap defining values for pixels of a background remaining constant for the frame sequence. The background depth data is represented by depth values defining distances between a view point reference and the geometric shapes at the pixels of the selected frame. For a selected geometric shape, a pixel is selected from a set of pixels for the frame. This set of pixels is defined by an intersection between the view point reference and the selected geometric shape. A determination is then made whether the selected geometric shape obscures another geometric shape at the selected pixel. If so, a value of the selected pixel is obtained and stored within the working frame buffer. In addition, a depth value defined by a distance between the view point reference and the selected geometric shape is stored within the working Z buffer. These steps are completed for each remaining pixel within the set of pixels and, in turn, this process is completed for each remaining geometric shape.