Abstract: Methods and coarse depth test logic perform coarse depth testing in a graphics processing system in which a rendering space is divided into a plurality of tiles. A depth range for a tile identifies a depth range based on primitives previously processed. A determination is made based on the depth range for the tile as to whether all or a portion of a primitive is hidden in the tile. If at least a portion of the primitive is not hidden in the tile, a determination is made as to whether the primitive or a primitive fragment thereof has better depth than the primitives previously processed for the tile. If so, the primitive or the primitive fragment is identified as not requiring a read of a depth buffer to perform full resolution depth testing, such that a determination that at least a portion of the primitive is hidden in the tile causes full resolution depth testing not to be performed on at least that portion of the primitive.

Abstract: Memories and methods for storing untransformed primitive blocks of variable size in a memory structure of a graphics processing system, the untransformed primitive blocks having been generated by geometry processing logic of the graphics processing system. The method includes: storing an untransformed primitive block in the memory structure, and increasing, by a predetermined amount, a current total amount of memory allocated for storing untransformed primitive blocks; determining an unused amount of the current total amount of memory allocated for storing untransformed primitive blocks; receiving a new untransformed primitive block for storing in the memory structure, and determining whether a size of the new untransformed primitive block is less than or equal to the unused amount; and if it is determined that the size of the new untransformed primitive block is less than or equal to the unused amount, storing the new untransformed primitive block in the memory structure.

Abstract: Tiling engines and methods for hierarchically tiling a plurality of primitives. A chain of sorting units includes a top level sorting unit followed by lower level sorting units, the top level sorting unit determining which of a plurality of regions of a render space each of the plurality of primitives at least partially falls within. For each region a primitive at least partially falls within an identifier of that primitive is stored in a queue. Each of the lower level sorting units selects queues of a preceding sorting unit in the chain to process, and determines which of a plurality of sub-regions of the region associated with that queue each of the primitives at least partially falls within. For each such sub-region an identifier of that primitive is stored in a queue of the lower level sorting unit that is associated with that sub-region. An output unit outputs the primitives identified in the queues of the last lower level sorting unit in the chain on a queue by queue basis.

Abstract: A graphics processing system for generating a rendering output includes geometry processing logic and rasterization logic. The geometry processing logic includes 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 of the one or more expansion transformation stages that indicates the sub-primitives generated for the untransformed primitives in that untransformed primitive block that are to be used in generating the rendering output.

Abstract: Methods and primitive block generators for generating primitive blocks in a graphics processing system. The methods comprise: 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: A cache for use in a tile-based rendering graphics processing system for storing transformed primitive blocks, the graphics processing system having a rendering space sub-divided into a plurality of tiles to which primitives can be associated, the graphics processing system comprising rasterization logic that rasterizes primitives on a per tile basis in a plurality of stages, the cache comprising: memory configured to store a plurality of transformed primitive blocks in the cache, each transformed primitive block comprising transformed geometry data for one or more primitives; control logic configured to: maintain a counter for each of the plurality of transformed primitive blocks stored in the cache that indicates a number of tiles of the plurality of tiles that are currently being processed by the rasterization logic and require access to that transformed primitive block, the counter being updated when any stage of the rasterization logic indicates a tile no longer requires access to the transformed primiti

Abstract: Methods and coarse depth test logic perform coarse depth testing in a graphics processing system in which a rendering space is divided into a plurality of tiles. A depth range for a tile is obtained, which identifies a depth range based on primitives previously processed for the tile. A determination is made based on the depth range for the tile as to whether all or a portion of a primitive is hidden in the tile. If at least a portion of the primitive is not hidden in the tile, a determination is as to whether the primitive, or one or more primitive fragments thereof has better depth than the primitives previously processed for the tile according to a depth compare mode. If so, the primitive or the primitive fragment is identified as not requiring a read of a depth buffer to perform full resolution depth testing, such that a determination that at least a portion of the primitive is hidden in the tile causes full resolution depth testing not to be performed on at least that portion of the primitive.

Abstract: A graphics processing system having a rendering space divided into a plurality of tiles. The system comprises geometry processing logic and rasterization logic. The geometry processing logic is configured to generate transformed position data for each of a plurality of untransformed primitives based on untransformed geometry data associated therewith; group the plurality of untransformed primitives into a plurality of primitive blocks; and generate an untransformed display list for each tile based on the transformed position data. Each untransformed display list comprises: (i) information identifying each untransformed primitive block that comprises at least one untransformed primitive that, when transformed, falls at least partially with the tile; and (ii) for each identified untransformed primitive bock, information identifying the untransformed primitives or transformed primitives related to that untransformed primitive block relevant for rendering the tile.

Abstract: Tiling engines and methods for use in a graphics processing system for hierarchically tiling a plurality of primitives.

Abstract: A graphics processing system for generating a rendering output includes geometry processing logic and rasterization logic. The geometry processing logic includes 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 of the one or more expansion transformation stages that indicates the sub-primitives generated for the untransformed primitives in that untransformed primitive block that are to be used in generating the rendering output.

Abstract: A method of managing access to a physical memory formed of n memory page frames using a set of virtual address spaces having n virtual address spaces each formed of a plurality p of contiguous memory pages. The method includes receiving a write request to write a block of data to a virtual address within a virtual address space i of the n virtual address spaces, the virtual address defined by the virtual address space i, a memory page j within that virtual address space i and an offset from the start of that memory page j; translating the virtual address to an address of the physical memory using a virtual memory table having n by p entries specifying mappings between memory pages of the virtual address spaces and memory page frames of the physical memory, wherein the physical memory address is defined by: (i) the memory page frame mapped to the memory page j as specified by the virtual memory table, and (ii) the offset of the virtual address; and writing the block of data to the physical memory address.

Abstract: Systems and methods for processing primitive fragments in a rasterization phase of a graphics processing system wherein a rendering space is subdivided into a plurality of tiles. The method includes receiving a plurality of primitive fragments, each primitive fragment corresponding to a pixel sample in a tile; determining whether a depth buffer read is to be performed for hidden surface removal processing of one or more of the primitive fragments; sorting the primitive fragments into a priority queue and a non-priority queue based on the depth buffer read determinations; and performing hidden surface removal processing on the primitive fragments in the priority and non-priority queues wherein priority is given to the primitive fragments in the priority queue.

Abstract: A cache for use in a tile-based rendering graphics processing system for storing transformed primitive blocks, the graphics processing system having a rendering space sub-divided into a plurality of tiles to which primitives can be associated, the graphics processing system comprising rasterization logic that rasterizes primitives on a per tile basis in a plurality of stages, the cache comprising: memory configured to store a plurality of transformed primitive blocks in the cache, each transformed primitive block comprising transformed geometry data for one or more primitives; control logic configured to: maintain a counter for each of the plurality of transformed primitive blocks stored in the cache that indicates a number of tiles of the plurality of tiles that are currently being processed by the rasterization logic and require access to that transformed primitive block, the counter being updated when any stage of the rasterization logic indicates a tile no longer requires access to the transformed primiti

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: Methods and graphics processing systems render primitives using a rendering space which is subdivided into a plurality of regions. Geometry processing logic performs a geometry processing phase which 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 present in the region, wherein the stored data comprises, for each of the primitives which are determined to totally cover the region, data to indicate total coverage of the region. Rendering logic performs a rendering phase for rendering primitives within the region.

Abstract: Methods and tiling engines for tiling primitives in a tile based graphics processing system in which a rendering space is divided into a plurality of tiles. The method includes generating a multi-level hierarchy of tile groups, each level of the multi-level hierarchy comprising one or more tile groups comprising one or more of the plurality of tiles; receiving a plurality of primitive blocks, each primitive block comprising geometry data for one or more primitives; associating each of the plurality of primitive blocks with one or more of the tile groups up to a maximum number of tile groups such that if at least one primitive of a primitive block falls, at least partially, within the bounds of a tile, the primitive block is associated with at least one tile group that includes that tile; and generating a control stream for each tile group based on the associations, wherein each control stream comprises a primitive block entry for each primitive block associated with the corresponding tile group.

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: 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 systems for storing a set of two or more variable length data blocks in memory. Each variable length data block having a maximum size of N*B, wherein N is an integer greater than or equal to two, and B is a maximum data size that can be written to the memory using a single memory access request. The method includes: storing, for each variable length data block of the set, the first P non-overlapping portions of size B of the variable length data block in a chunk of the memory allocated to that variable length data block, wherein P is a minimum of (i) a number of non-overlapping portions of size B of the variable length data block and (ii) X which is an integer less than N; storing any remaining portions of the variable length data blocks in a remainder section of the memory that is shared between the variable length data blocks of the set; and storing in a header section of the memory information indicating the size of each of the variable length data blocks in the set.

Abstract: A method of managing access to a physical memory formed of n memory page frames using a set of virtual address spaces having n virtual address spaces each formed of a plurality p of contiguous memory pages. The method includes receiving a write request to write a block of data to a virtual address within a virtual address space i of the n virtual address spaces, the virtual address defined by the virtual address space i, a memory page j within that virtual address space i and an offset from the start of that memory page j; translating the virtual address to an address of the physical memory using a virtual memory table having n by p entries specifying mappings between memory pages of the virtual address spaces and memory page frames of the physical memory, wherein the physical memory address is defined by: (i) the memory page frame mapped to the memory page j as specified by the virtual memory table, and (ii) the offset of the virtual address; and writing the block of data to the physical memory address.