Method of and apparatus for processing graphics

Abstract

A scene 50 to be rendered is divided into plural individual sub-regions or tiles 51. The individual sub-regions 51 are also grouped into differing groups of sets of plural sub-regions. There is a top level layer comprising a set 54 of 8×8 sub-regions which encompasses the entire scene area 50 . There is then a group of four 4×4 sets of sub-regions 53 , then a group of sixteen 2×2 sets of sub-regions 52 , and finally a layer comprising the 64 single sub-regions 51. A primitive list building unit takes each primitive 80 in turn, determines a location for that primitive, compares the primitive's location with the locations of the sub-regions 51 and the locations of the sets of sub-regions 52, 53 and 54 , and allocates the primitive to respective primitive lists for the sub-regions and sets of sub-regions accordingly.

1 . An apparatus for sorting graphics primitives for rendering in a graphics processing system in which a scene to be rendered is divided into a plurality of sub-regions for rendering, the apparatus comprising: 
 a processor for preparing, for a single sub-region of the scene, a list of primitives for rendering; and    a processor for preparing, for a set of sub-regions comprising more than one sub-region of the scene, a list of primitives for rendering.    
     
     
         2 . An apparatus of  claim 1 , comprising: 
 a processor for including a primitive to be rendered in one or more lists of primitives to be rendered; wherein:    the lists of primitives to be rendered include one or more lists of primitives to be rendered that are to be used exclusively for single sub-regions of the scene, and include one or more different lists of primitives to be rendered that are each to be used for more than one sub-region of the scene.    
     
     
         3 . The apparatus of  claim 1 , wherein primitive lists can be prepared for sets of plural sub-regions that contain different numbers of sub-regions.  
     
     
         4 . The apparatus of  claim 1 , wherein the sets of plural sub-regions for which primitive lists can be prepared are arranged such that the scene is effectively overlaid by plural layers of sets of sub-regions arranged in a hierarchical fashion.  
     
     
         5 . The apparatus of  claim 1 , wherein a separate primitive list is prepared for each separate sub-region that the scene is divided into, and a separate primitive list is prepared for each different set of more than one sub-region that a primitive list can be prepared for.  
     
     
         6 . The apparatus of  claim 1 , wherein a given primitive is only included in the primitive lists of a selected number of the sub-regions and sets of plural sub-regions that it is determined the primitive could or should be rendered for.  
     
     
         7 . The apparatus of  claim 1 , wherein when a primitive is included in a primitive list for a set of plural sub-regions, the primitive is not also included in the individual primitive lists for any of the sub-regions that are in the set of plural sub-regions.  
     
     
         8 . The apparatus of  claim 1 , wherein there are sets of plural sub-regions arranged such that the scene is effectively overlaid by plural layers of different size scene areas, and the apparatus further comprises: 
 a processor for determining how many different primitive lists a primitive would need to be included in at given layer in the sets of sub-regions hierarchy.    
     
     
         9 . The apparatus of  claim 1 , wherein each sub-region has associated with it a set of primitive lists to be used for the sub-region.  
     
     
         10 . The apparatus of  claim 1 , comprising means for allocating an index to a primitive.  
     
     
         11 . A graphics processing system, comprising: 
 means for listing graphic primitives for rendering;    means for associating with each listed graphics primitive an index for the primitive; and    means for using the indices associated with the graphics primitives to sort the primitives.    
     
     
         12 . The apparatus of  claim 1 , comprising means for storing other forms of graphics data and/or commands in the primitive lists for the sub-regions and sets of sub-regions.  
     
     
         13 . A method of sorting graphics primitives for rendering in a graphics processing system in which a scene to be rendered is divided into a plurality of sub-regions for rendering, the method comprising 
 preparing a list of primitives for rendering for a single sub-region of the scene; and    preparing a list of primitives for rendering for a set of sub-regions comprising more than one sub-region of the scene.    
     
     
         14 . The method of  claim 13 , comprising: 
 including a primitive to be rendered in one or more lists of primitives to be rendered; wherein:    the lists of primitives to be rendered include one or more lists of primitives to be rendered that are to be used exclusively for single sub-regions of the scene, and include one or more different lists of primitives to be rendered that are each to be used for more than one sub-region of the scene.    
     
     
         15 . The method of  claim 13 , comprising preparing primitive lists for sets of plural sub-regions that contain different numbers of sub-regions.  
     
     
         16 . The method of  claim 13 , wherein the sets of plural sub-regions for which primitive lists can be prepared are arranged such that the scene is effectively overlaid by plural layers of sets of sub-regions arranged in a hierarchical fashion.  
     
     
         17 . The method of  claim 13 , comprising preparing a separate primitive list for each separate sub-region that the scene is divided into, and preparing a separate primitive list for each different set of more than one sub-region that a primitive list can be prepared for.  
     
     
         18 . The method of  claim 13 , comprising only including a primitive in the primitive lists of a selected number of the sub-regions and sets of plural sub-regions that it is determined the primitive could or should be rendered for.  
     
     
         19 . The method of  claim 13 , comprising when a primitive is included in a primitive list for a set of plural sub-regions, not including the primitive in the individual primitive lists for any of the sub-regions that are in the set of plural sub-regions.  
     
     
         20 . The method of  claim 13 , wherein there are sets of plural sub-regions arranged such that the scene is effectively overlaid by plural layers of different size scene areas, and the method further comprises: 
 determining how many different primitive lists a primitive would need to be included in a given layer in the sets of sub-regions hierarchy.    
     
     
         21 . The method of  claim 13 , comprising associating with each sub-region a set of primitive lists to be used for the sub-region.  
     
     
         22 . The method of  claim 13 , comprising allocating an index to a primitive.  
     
     
         23 . A method of operating a graphics processing system, comprising: 
 listing graphic primitives for rendering;    associating with each listed graphics primitive an index for the primitive; and    using the indices associated with the graphics primitives to sort the primitives.    
     
     
         24 . A method of processing a group of graphics primitives for display, comprising: 
 allocating an index to primitives in the group of primitives;    distributing primitives from the group of primitives across multiple processing units;    rendering primitives from the group of primitives; and    using the indices allocated to the primitives to control the order in which the primitives are rendered.    
     
     
         25 . The method of  claim 13 , comprising storing other forms of graphics data and/or commands in the primitive lists for the sub-regions and sets of sub-regions.  
     
     
         26 . A 3D graphics processing platform for a graphics processing system in which a scene to be rendered is divided into a plurality of sub-regions for rendering, the platform comprising: 
 a processor for preparing, for a single sub-region of the scene, a list of primitives for rendering; and    a processor for preparing, for a set of sub-regions comprising more than one sub-region of the scene, a list of primitives for rendering.    
     
     
         27 . A computer program element comprising computer software code portions for performing a method of sorting graphics primitives for rendering in a graphics processing system in which a scene to be rendered is divided into a plurality of sub-regions for rendering, the method comprising 
 preparing a list of primitives for rendering for a single sub-region of the scene; and    preparing a list of primitives for rendering for a set of sub-regions comprising more than one sub-region of the scene.