Depth buffer compression

Abstract

Device, computer readable medium, and method for selecting compression modes to be applied in a depth buffer (20). The method includes obtaining values corresponding to a tile (30) of the depth buffer (20), selecting a first compression mode (34) from a first plurality of compression modes, compressing the values of the tile (30), writing the compressed values into a first block, based on the first mode (34), and using a preset number of primary bits (34) to store information related to at least one of the first mode (34) and a compression size of the first block, selecting a set of secondary compression modes (32) from a second plurality of compression modes, determining a number of sub-tiles (28), that make up the tile (30), compressing values of the sub-tiles, writing the compressed values into a second block, based on the set of secondary modes (32), and using the same preset number of primary bits (34) to store information related to at least one of the set of secondary modes (32) and a compression size of the second block, comparing the compression size of the tile (30) to the compression size of the sub-tiles (28), choosing the first mode (34) or the set of secondary modes (32) and a corresponding tile size based on a result of the comparing, and storing the selected compressed tile or sub-tiles into the depth buffer (20) and writing into the preset number of primary bits (34) information related to the chosen first mode (34) or set of secondary compression modes (32) or a corresponding size.

Description

[0001] related application [0002] This application is related to and claims priority from U.S. Provisional Patent Application (Serial No. 60 / 971692) to P. Wennersten, entitled "BlockiBlock Improved Depth Buffer Compression," filed September 12, 2007, the full disclosure of which Incorporated herein by reference. technical field [0003] The present invention relates generally to selecting a compression mode for compressing data, and more particularly to methods and apparatus for implementing multi-tile based compression of depth buffer image data. Background technique [0004] The demand for processing three-dimensional graphics on mobile communication devices is increasing. Real-time rendering of three-dimensional graphics has several attractive applications, such as video games, human-machine interfaces, messaging, and mobile e-commerce (m-commerce). Users of communication devices prefer to visualize the objects they are interacting with, and thus three-dimensional gra...

AI Technical Summary

Problems solved by technology

A more complex approach that works for many triangles may be too expensive to implement

In other words, an architecture designed to efficiently compress 4x4 slices is not equally efficient at compressing 8x8 slices

Also, tile size affects much more than just depth buffer compression, so it's not just a matter of choosing the tile size that results in the best compression ratio

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