Abstract: Methods and graphics processing systems render items of geometry using a rendering space which is subdivided into a plurality of first regions. Each of the first regions is sub-divided into a plurality of second regions. Each of a plurality of items of geometry is processed by identifying which of the first regions the item of geometry is present within, and for each identified first region determining an indication of the spatial coverage, within the identified first region, of the item of geometry, and using the determined indication of the spatial coverage within the identified first region to determine whether to add the item of geometry to a first control list for the identified first region or to add the item of geometry to one or more second control lists for a respective one or more of the second regions within the identified first region.

Abstract: A graphics processing system renders primitives using a rendering space which is sub-divided into a plurality of regions. Geometry processing logic performs a geometry processing phase for a current render wherein for each region in the plurality of regions it is determined, for each of a plurality of primitives which are present in the region, whether the primitive totally covers the region, and total coverage data is stored indicating which of the primitives which are present in the region totally cover the region. Rendering logic performs, after the geometry processing logic has completed the geometry processing phase for the current render, a rendering phase for each of the regions of the plurality of regions on a region-by-region basis for the current render using the total coverage data for the region.

Abstract: Data structures, methods and tiling engines for storing tiling data in memory wherein the tiles are grouped into tile groups and the primitives are grouped into primitive blocks. The methods include, for each tile group: determining, for each tile in the tile group, which primitives of each primitive block intersect that tile; storing in memory a variable length control data block for each primitive block that comprises at least one primitive that intersects at least one tile of the tile group; and storing in memory a control stream comprising a fixed sized primitive block entry for each primitive block that comprises at least one primitive that intersects at least one tile of the tile group, each primitive block entry identifying a location in memory of the control data block for the corresponding primitive block. Each primitive block entry may comprise valid tile information identifying which tiles of the tile group are valid for the corresponding primitive block.

Abstract: Methods and primitive block generators for generating primitive blocks in a graphics processing system. The methods include receiving transformed position data for a current primitive, the transformed position data indicating a position of the current primitive in rendering space; determining a distance between the position of the current primitive and a position of a current primitive block based on the transformed position data for the current primitive; determining whether to add the current primitive to the current primitive block based on the distance and a fullness of the current primitive block; in response to determining that the current primitive is to be added to the current primitive block, adding the current primitive to the current primitive block; and in response to determining that the current primitive is not to be added to the current primitive block, flushing the current primitive block and adding the current primitive to a new current primitive block.

Abstract: Methods and apparatus for merging tasks in a graphics pipeline in which, subsequent to a trigger to flush a tag buffer, one or more tasks from the flushed tag buffer are generated, each task comprising a reference to a program and plurality of fragments on which the program is to be executed, wherein a fragment is an element of a primitive at a sample position. It is then determined whether merging criteria are satisfied and if satisfied, one or more fragments from a next tag buffer flush are added to a last task of the one or more tasks generated from the flushed tag buffer.

Abstract: A method of performing lossy compression on a block of image data in accordance with a multi-level difference table determines an origin value for the block of image data, and determines a level within the multi-level difference table for the block of image data, by determining a maximum difference between the determined origin value and any one of image element values in the block of image data and selecting from the multi-level difference table the level whose largest entry most closely represents the determined maximum difference. For each image element value in the block, one of the entries at the determined level within the multi-level difference table is selected, and a compressed block of data for the block of image data is formed, the compressed block of data including (i) data representing the determined origin value, (ii) an indication of the determined level, and (iii) for each image element value in the block of image data, an indication of the selected entry for that image element value.

Abstract: A graphics processing system for generating a rendering output includes geometry processing logic having first transformation logic configured to transform a plurality of untransformed primitives into a plurality of transformed primitives, the first transformation logic configured to implement one or more expansion transformation stages which generate one or more sub-primitives; a primitive block generator configured to divide the plurality of transformed primitives into a plurality of groups; and generate an untransformed primitive block for each group comprising (i) information identifying the untransformed primitives related to the transformed primitives in the group; and (ii) an expansion transformation stage mask for at least one or more expansion transformation stages that indicates the sub-primitives generated for the untransformed primitives in that untransformed primitive block used in generating the rendering output.

Abstract: Graphics processing renders primitives using a rendering space which is subdivided into a plurality of regions. A geometry processing phase determines, for each of a plurality of primitives which are present in a region, whether the primitive totally covers the region and stores data for the primitives which are determined to totally cover the region to indicate total coverage of the region. A rendering phase retrieves the stored data for the primitives which are present in the region, selectively processes primitives which are present in the region based on the retrieved data to determine which sample points within the region are covered by the primitives, wherein if the retrieved data includes data which indicates total coverage of the region for a particular primitive then the processing determining sample points is skipped; and determines rendered values at the sample points within the region based on the primitives which cover the respective sample points.

Abstract: A computer-implemented method and a decompression unit for decompressing a compressed block of data in accordance with a multi-level difference table. The compressed block of data represents a block of image data comprising a plurality of image element values, wherein each level of the multi-level difference table comprises a plurality of entries. An origin value for the block of image data is determined using data representing the origin value from the compressed block of data. A level within the multi-level difference table for the block of image data is identified using an indication of the level from the compressed block of data.

Abstract: Methods and apparatus for merging tasks in a graphics pipeline in which, subsequent to a trigger to flush a tag buffer, one or more tasks from the flushed tag buffer are generated, each task comprising a reference to a program and plurality of fragments on which the program is to be executed, wherein a fragment is an element of a primitive at a sample position. It is then determined whether merging criteria are satisfied and if satisfied, one or more fragments from a next tag buffer flush are added to a last task of the one or more tasks generated from the flushed tag buffer.

Abstract: Methods and decompression units for decompressing a selected sub-block of image element values from a compressed block of image element values. The method includes: identifying, from the compressed block of image element values, a pattern of a plurality of patterns of image element values associated with the selected sub-block; identifying, from the compressed block of image element values, one or more image element values associated with the selected sub-block; and generating the selected sub-block from the pattern and the one or more image element values associated with the selected sub-block.

Abstract: A method of processing primitives within a tiling unit of a graphics processing system comprises determining whether a primitive falls within a tile based on positions of samples within each pixel. If it is determined that the primitive does fall within a tile based on the positions of samples within pixels in a tile, an association between the tile and the primitive is stored to indicate that the primitive is present in the tile. For example, an identifier for the primitive may be added to a control stream for the tile to indicate that the primitive is present in the tile. Various different methods are described to make the determination and these may be used separately or in any combination.

Abstract: Methods and compression units for compressing a block of image data, the block of image data comprising a plurality of image element values, the image element values being divisible into at least a first value and a second value such that the block of image data comprises a two-dimensional block of first values, the method comprising: compressing a first data set comprising all or a portion of the two-dimensional block of first values in accordance with a first fixed-length compression algorithm to generate a first compressed block by: identifying common base information for the first data set; and identifying a fixed-length parameter for each first value in the first data set, the fixed-length parameter being zero, one or more than one bits in length; and forming a compressed block for the block of image data based on the first compressed block.

Abstract: Methods and control stream generators for generating a control stream for a tile group comprising at least two tiles, the control stream identifying primitive blocks that are relevant to rendering at least one tile in the tile group.

Abstract: A computer-implemented method and a compression unit for performing lossy compression on a block of image data in accordance with a multi-level difference table. The block of image data comprises a plurality of image element values, wherein each level of the multi-level difference table comprises a plurality of entries. An origin value for the block of image data is determined. A level within the multi-level difference table for the block of image data is determined. For each image element value in the block of image data, one of the entries at the determined level within the multi-level difference table is selected. A compressed block of data for the block of image data is formed, wherein the compressed block of data comprises: (i) data representing the determined origin value, (ii) an indication of the determined level, and (iii) for each image element value in the block of image data, an indication of the selected entry for that image element value.

Abstract: Data structures, methods and tiling engines for storing tiling data in memory wherein the tiles are grouped into tile groups and the primitives are grouped into primitive blocks. The methods include, for each tile group: determining, for each tile in the tile group, which primitives of each primitive block intersect that tile; storing in memory a variable length control data block for each primitive block that comprises at least one primitive that intersects at least one tile of the tile group; and storing in memory a control stream comprising a fixed sized primitive block entry for each primitive block that comprises at least one primitive that intersects at least one tile of the tile group, each primitive block entry identifying a location in memory of the control data block for the corresponding primitive block. Each primitive block entry may comprise valid tile information identifying which tiles of the tile group are valid for the corresponding primitive block.

Abstract: A method and system for processing graphics in tile-based rendering mode are disclosed. The system includes: a geometry processing system configured to perform geometry processing on primitives to tile visible primitives into a plurality of tiles M in screen view space; and a fragment processing system configured to render the plurality of tiles M to generate rendered images of the plurality of tiles M. The fragment processing system includes a post-processing module configured to start to perform pixel filtering on pixels in a first pixel set Pin0 of a target tile M0 in the plurality of tiles M at a first time after a rendered image of the target tile M0 is generated and before all the rendered images of the plurality of tiles M are generated. The present disclosure can effectively improve processing efficiency of overall image pixel filtering, without generating additional pixel shading workload.

Abstract: A method and system for processing graphics in tile-based rendering mode are disclosed. The system includes: a geometry processing system configured to perform geometry processing on primitives to tile visible primitives into a plurality of tiles M in screen view space; and a fragment processing system configured to render the plurality of tiles M and generate rendered images of the plurality of tiles M, where the fragment processing system includes a post-processing module configured to: start to perform pixel filtering on pixels in a first pixel set Pin0 of a target tile M0 in the plurality of tiles M at a first time after a rendered image of the target tile M0 is generated and before all the rendered images of the plurality of tiles M are generated. The present disclosure can effectively improve processing efficiency of overall image pixel filtering, without generating additional pixel shading workload.

Abstract: A method of processing primitives within a tiling unit of a graphics processing system comprises determining whether a primitive falls within a tile based on positions of samples within each pixel. If it is determined that the primitive does fall within a tile based on the positions of samples within pixels in a tile, an association between the tile and the primitive is stored to indicate that the primitive is present in the tile. For example, an identifier for the primitive may be added to a control stream for the tile to indicate that the primitive is present in the tile. Various different methods are described to make the determination and these may be used separately or in any combination.

Abstract: Methods and primitive block generators for generating primitive blocks in a graphics processing system. The methods include receiving transformed position data for a current primitive, the transformed position data indicating a position of the current primitive in rendering space; determining a distance between the position of the current primitive and a position of a current primitive block based on the transformed position data for the current primitive; determining whether to add the current primitive to the current primitive block based on the distance and a fullness of the current primitive block; in response to determining that the current primitive is to be added to the current primitive block, adding the current primitive to the current primitive block; and in response to determining that the current primitive is not to be added to the current primitive block, flushing the current primitive block and adding the current primitive to a new current primitive block.