Every once in a while I find that trying to read and decipher one of Apple's patents is painfully like being an archeologist trying to find meaning in an ancient manuscript that's written in some form of Sanskrit. I'm not even going to pretend to understand the depths of this never ending granted patent which contains in excess of 200 patent figures. All that matters is that Apple's granted patent states emphatically that the invention is about a new graphics processor and method. The graphics processor is specifically referred to as a Deferred Shading Graphics Processor or DSGP. The invention relates to computing systems, to 3D computer graphics and particularly to structure and method for a 3D graphics processor implementing differed shading and other enhanced features. The granted patent appears to be discussing a desktop/workstation graphics processor and interestingly, Apple may have acquired this patent. The lead inventor, listed as Jerome Duluk, used to work at NVIDIA.
Patent Summary In-Part
A part of Apple's summary states that "computer graphics is the art and science of generating pictures or images with a computer. This picture generation is commonly referred to as rendering. The appearance of motion, for example in a 3-Dimensional animation is achieved by displaying a sequence of images. Interactive 3-Dimensional (3D) computer graphics allows a user to change his or her viewpoint or to change the geometry in real-time, thereby requiring the rendering system to create new images on-the-fly in real-time. Therefore, real-time performance in color, with high quality imagery is becoming increasingly important.
The invention is directed to a new graphics processor and method and encompasses numerous substructures including specialized subsystems, subprocessors, devices, architectures, and corresponding procedures. Embodiments of the invention may include one or more of deferred shading, a tiled frame buffer, and multiple-stage hidden surface removal processing, as well as other structures and/or procedures. In this document, this graphics processor is hereinafter referred to as the DSGP (for Deferred Shading Graphics Processor), or the DSGP pipeline, but is sometimes referred to as the pipeline.
This present invention includes numerous embodiments of the DSGP pipeline. Embodiments of the present invention are designed to provide high-performance 3D graphics with Phong shading, subpixel anti-aliasing, and texture- and bump-mapping in hardware. The DSGP pipeline provides these sophisticated features without sacrificing performance."
The DSGP will support both OpenGL and Direct3D APIs which are used in Microsoft's Xbox.
One of the things that Apple's patent covers is Deferred Shading and states that "hidden surface removal" (HSR) is a complicated process in OpenGL. The patent then goes on to present a superior alternative to that process which it calls the "conservative hidden surface removal" (CHSR). You'll have to refer to the patent for all the particulars.
For the Archeologist in all of Us
In my introduction, I stated that reading and deciphering some of Apple's patents is "painfully like being an archeologist trying to find meaning in an ancient manuscript that's written in some form of Sanskrit." Well, you're about to get a taste of that means. Below is a list from the actual patent describing some of the content that could be found in today's granted patent, as follows:
Three-Dimensional Graphics Deferred Shader Architecture; Conservative Hidden Surface Removal; Tile Prefetch; Context Switching; Multipass by SRT for Better Antialiasing; Selection of Sample Locations; Sort Before Setup; Tween Packets; Packetized Data Transfer; Alpha Test, Blending, Stippled Lines, and the like; Chip Partitioning; Object Tags (especially in Deferred Shading Architecture); Logarithmlc Normalization in Color Space (Floating Point Colors); Backend Microarchitecture; Pixel Zooming During Scanout; Virtual Block Transfer (BLT) on Scanout; Pixel Ownership; Window ID; Blocking and Non-blocking Interrupt Mechanism; Queuing Mechanisms; Token Insertion for Vertex Lists; Hidden Surface Removal; Tiled Content Addressable Z-buffer; three-stage Z-buffer Process; dealing with Alpha Test and Stencil in a Deferred Shader; Sending Stamps Downstream with Z Ref and Dz/dx and Dxtdy; Stamp Portion Memory Separate from the Z-buffer Memory; Sorted Transparency Algorithm; Finite State Machine per Sample; a SAM Implementation; Fragment Microarchitecture; GEO Microarchitecture; Pipestage Interleaving; Polygon Clipping Algorithm; 2-Dimensional Block Microarchitecture; Zero-to-one Inclusive Multiplier (Mul-18p); Integer-floating-integer (Ifi) Match Unit; Taylor Series Implementation; Math Block Construction Method; Multi-chip Communication Ring Graphics; How to Deal with Modes in a Deferred Shader; Mode Catching; MLM Pointer Storage; Clipped Polygons in Sort Whole in Polygon Memory; Phong/bump Microarchitecture; Material-tag-based Resource Allocation of Fragment Engines; Dynamic Microcode Generation for Texture Environment and Lighting; How to Do Tangent Space Lighting in a Deferred Shading Architecture; Variable Scale Bump Maps; Automatic Basis Generation; Automatic Gradient-field Generation Normal Interpolation by Doing Angle and Magnitude Separately; Post-tile-sorting Setup Operations in Deferred Shader, Unified Primitive Description; Tile-relative Y-values and Screen Relative X-values; Hardware Tile Sorting; Enough Space Look ahead Mechanism; Touched Tile Implementation; Texture Re-use Matching Registers (Including Deferred Shader); Samples Expanded to Pixels (Texture Miss Handling); Tile Buffers and Pixel Buffers (Texture Microarchitecture); and packetized data transfer in a processor.
I think it's pretty safe to say that if the study of graphic processors wasn't your major, you're never going to be able to understand the heart of this patent. But if this is your field of expertise, then you'll have a great weekend read.
Various Deferred Shading Graphics Processor Patent Figures
Over 200 patent figures accompanied this extensively detailed patent. This report only presents six randomly chosen graphics in relation to Apple's Deferred Graphics Processor.
Apple credits the inventors of granted patent 7,808,503 as follows:
Duluk, Jr.; Jerome F. (Palo Alto, CA), Hessel; Richard E. (Pleasanton, CA), Arnold; Vaughn T. (Scotts Valley, CA), Benkual; Jack (Cupertino, CA), Bratt; Joseph P. (San Jose, CA), Cuan; George (Sunnyvale, CA), Dodgen; Stephen L. (Boulder Creek, CA), Fang; Emerson S. (Fremont, CA), Gong; Zhaoyu (Cupertino, CA), Yo; Thomas Y. (Fremont, CA), Hsu; Hengwei (Fremont, CA), Li; Sidong (San Jose, CA), Ng; Sam (Fremont, CA), Papakipos; Matthew N. (Menlo Park, CA), Redgrave; Jason R. (Mountain View, CA), Trivedi; Sushma S. (Sunnyvale, CA), Tuck; Nathan D. (San Diego, CA), Go; Shun Wai (Milpitas, CA), Fung; Lindy (Sunnyvale, CA), Nguyen; Tuan D. (San Jose, CA), Grass; Joseph P. (Menlo Park, CA), Hong; Bo (San Jose, CA), Mammen; Abraham (Pleasanton, CA), Rashid; Abbas (Fremont, CA), Tsay; and Albert Suan-Wei (Fremont, CA).
The patent's verbiage would dictate that the processor technology is far from "new" being that it covers such things as AGP (Accelerated Graphics Port) which was phased out in 2004. Additionally, this latest version of the patent now incorporates other patents which actually date back to 2003 and even as far back as 1998. Then again, if the patent was recently acquired by Apple, then the technology would very much be new to Apple. The question becomes, is the technology that's represented in this granted patent already buried in Apple's current Mac line-up or is this technology being reserved for future hardware to support advanced 3D gaming and/or a 3D version of OS X? That's the million dollar question. For now, however, the news we could bank on is that Apple has been granted a patent for a very sophisticated graphic processor.
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