System and method for implementing a two-layer z-range buffer

In a graphics display system having a digital circuit topology having a set of primary input gates and a set of primary output gates, a method of detecting hidden surfaces of a polygon in a display block, the polygon having depth values corresponding to a minimum depth value and a maximum depth value, the method comprising:

• storing in a z-range buffer minimum and maximum depth values for the layers in the block, the z-range buffer further storing a bitmask value, each bit in the bitmask value associating a pixel in the block to a layer in the block;
• comparing a depth value of the polygon with a depth value of a particular layer in the block stored in the z-range buffer;
• and
• identifying visible pixels in the block making up the polygon based on the comparison.

A computer-readable medium comprising:

• a program code embodied in the computer readable medium for causing detection of hidden surfaces of a polygon in a display block, the polygon having depth values corresponding to a minimum depth value and a maximum depth value, the computer-readable program segment comprising instructions for performing the steps of:
• storing in a z-range buffer minimum and maximum depth values for the layers in the block, the z-range buffer further storing a bitmask value, each bit in the bitmask value associating a pixel in the block to a layer in the block;
• comparing a depth value of the polygon with a depth value of a particular layer in the block stored in the z-range buffer;
• and
• identifying visible pixels in the block making up the polygon based on the comparison.

In a computer graphics display system comprising a display monitor, a method of detecting hidden surfaces of a polygon in a display block, the polygon having depth values corresponding to a minimum depth value and a maximum depth value, the method comprising:

• partitioning a screen of the display monitor into a plurality of display blocks having one or more layers of pixels;
• storing in a z-range buffer minimum and maximum depth values for the layers in the block, the z-range buffer further storing a bitmask value, each bit in the bitmask value associating a pixel in the block to a layer in the block;
• comparing a depth value of the polygon with a depth value of a particular layer in the block stored in the z-range buffer;
• and
• identifying visible pixels in the block making up the polygon based on the comparison;
• the layers in the block comprise a first layer and a second layer, each pixel in the block being associated with either the first layer or the second layer, the first layer having depth values ranging from a first minimum depth value to a first maximum depth value, and the second layer having depth values ranging from a second minimum depth value to a second maximum depth value.