Method for encoding bounding boxes of drawing primitives to be rendered for multi-resolution supersampled frame buffers

Abstract

A method of encoding and storing locations of bounding boxes of drawing primitives to be rendered on a multi-resolution display that includes a plurality of regions of different resolution, at least one of which is subdivided into a plurality of sub-regions. The method includes steps of dividing the viewable area of the multi-resolution display into four quadrants and encoding only selected attributes of each of the plurality of bounding box locations within only one of the four quadrants of the multi-resolution display. The encoded selected attributes are then stored in a number of locations of a memory. The selected attributes include information regarding the regions of different resolutions within the multi-resolution display and the boundary lines therebetween, such as the region of lowest resolution partially covered by each of the bounding boxes; either the number of boundary lines cutting each of the bounding boxes or the number of sub bounding boxes forming each of the bounding boxes; either the direction of the first boundary line cutting through each of the bounding boxes or the direction of the sub-region of lowest resolution partially covered by each of the bounding boxes; and an indication as to whether a portion of the region of lowest resolution appears on both sides of the first cut cutting through each of the bounding boxes.

What is claimed is: 
     
       1. A method of encoding and storing locations of bounding boxes of drawing primitives to be rendered on a multi-resolution display, comprising the steps of: dividing a viewable area of the multi-resolution display into four quadrants;   encoding only selected attributes of each of a plurality of bounding box locations within only one of the four quadrants of the multi-resolution display, the selected attributes including information regarding regions and sub-regions of different resolutions within the multi-resolution display and boundary lines therebetween; and   storing the encoded selected attributes in a memory.   
     
     
       2. The encoding and storing method of claim 1, wherein the dividing step divides the viewable area along two lines of symmetry to create the four quadrants. 
     
     
       3. The encoding and storing method of claim 1, wherein the dividing step divides the viewable area along two perpendicular lines of symmetry, whereby the four quadrants are created within the viewable area of the multi-resolution display. 
     
     
       4. The encoding and storing method of claim 1, wherein at least one of the regions is subdivided into a plurality of sub-regions by boundary lines, and wherein the selected attributes include information relative to a region of lowest resolution partially covered by each of the bounding boxes; one of a number of boundary lines cutting each of the bounding boxes and a number of sub bounding boxes forming each of the bounding boxes; one of a direction of a first boundary line cutting through each of the bounding boxes and a direction of a sub-region of lowest resolution partially covered by each of the bounding boxes; and an indication as to whether a portion of the region of lowest resolution appears on both sides of the first boundary line cutting through each of the bounding boxes. 
     
     
       5. The encoding and storing method of claim 1, wherein the viewable area of the multi-resolution display includes first, second and third nested regions of progressively higher resolution, the first and second regions each being divided into four sub-regions, and wherein the storing step stores the selected attributes in thirty six memory locations, the thirty six locations corresponding to a number of all possible bounding box locations within one of the four quadrants. 
     
     
       6. The encoding and storing method of claim 1, wherein the multi-resolution display includes a peripheral region, a medial region and a foveal region, the foveal region being an innermost region and having a highest resolution, the peripheral and medial regions each being divided into four sub-regions separated by the boundary lines, and wherein the selected attributes include two bits to specify a region of lowest resolution for each of the bounding boxes; two bits to specify one of a number of boundary lines cutting each of the bounding boxes and a number of sub bounding boxes contained within each of the bounding boxes, one bit to specify one of a direction of a first boundary line cutting through each of the bounding boxes and a direction of a sub-region of lowest resolution, and one bit to specify whether a portion of the region of lowest resolution appears on both sides of the first boundary line cutting through each of the bounding boxes. 
     
     
       7. The encoding and storing method of claim 1, wherein the storing step stores the selected attributes in thirty-six discrete memory locations as six bit data words. 
     
     
       8. The encoding and storing method of claim 1, wherein the storing step is carried out by alternatively synthesizing a logic expression and by programming one of a Random Access Memory (RAM), a Read Only memory (ROM), and a Programmable Logic Array (PLA). 
     
     
       9. The encoding and storing method of claim 1, wherein the drawing primitives are triangles. 
     
     
       10. The encoding and storing method of claim 1, wherein the bounding boxes are bin bounding boxes and wherein the encoding step encodes selected attributes of the locations of a plurality of bin bounding boxes. 
     
     
       11. A method of encoding locations of bounding boxes of drawing primitives for a multi-resolution fame buffer, comprising the steps of: dividing a viewable area of a multi-resolution display into four quadrants along two lines of symmetry;   encoding bounding box locations only within one of the four quadrants;   setting at least one variable from which bounding box locations encoded within the one of the four quadrants of the viewable area may be extrapolated to an entire viewable area of the display.   
     
     
       12. The encoding method of claim 11, wherein the setting step sets a first and a second bit for the encoded bounding box location, the first and second bit indicating whether each encoded bounding box location should be flipped left to right, and bottom to top, respectively, to extrapolate the location of each of the encoded bounding box locations in each of the four quadrants from the encoded bounding box locations in the one quadrant. 
     
     
       13. A method of encoding bounding boxes of primitives to be rendered on a multi-resolution display having a plurality of regions of different resolutions, at least one of the regions comprising a plurality of sub-regions, the regions and sub-regions being delimited by boundary lines, the method comprising: a first encoding step to encode a region of lowest resolution that is partially covered by each of the bounding boxes;   a second encoding step to encode one of a number of boundary lines cutting each of the bounding boxes and a number of sub bounding boxes contained within the bounding box;   a third encoding step to encode one of a direction of a first cut and a direction of a sub region of lowest resolution that is partially covered by each of the bounding boxes; and   a fourth encoding step to encode whether a portion of the region of lowest resolution appears on both sides of the first cut cutting through each of the bounding boxes.   
     
     
       14. The encoding method of claim 13, wherein the multi resolution display comprises three regions, and the first encoding step sets two bits to encode the region of lowest resolution; the second encoding step sets two bits to encode one of the number of boundary lines cutting each of the bounding boxes and the number of sub bounding boxes contained within each of the bounding boxes; the third encoding step sets one bit to encode one of the direction of the first boundary line and the direction of the sub-region of lowest resolution partially covered by each of the bounding boxes; and the fourth encoding step sets one bit to encode whether a portion of the region of lowest resolution appears on both sides of the first cut cutting through each of the bounding boxes. 
     
     
       15. A method of specifying and storing locations of bounding boxes of primitives to be rendered on a display, comprising the steps of: dividing a viewable area of the display along two perpendicular lines of symmetry to create four quadrants;   encoding locations of bounding boxes of primitives to be rendered in only one of the four quadrants;   setting a first and a second bit for the encoded location of each the bounding boxes, the first and second bits indicating whether each encoded bounding box location should be flipped left to right, and bottom to top, respectively, to derive a location of each of the encoded bounding boxes in each of the four quadrants from the encoded location in the one quadrant; and   storing the encoded locations in a memory,   whereby, encoding bounding box locations in only one quadrant reduces a size of the memory needed to encode all bounding box locations within the display.