Abstract: A computing system comprises graphics rendering logic and image processing logic. The graphics rendering logic processes graphics data to render an image using a rendering space which is sub-divided into a plurality of tiles. Cost indication logic obtains a cost indication for each of a plurality of sets of one or more tiles of the rendering space, wherein the cost indication for a set of one or more tiles is suggestive of a cost of processing rendered image values for a region of the rendered image corresponding to the set of one or more tiles. The image processing logic processes rendered image values for regions of the rendered image. The computing system causes the image processing logic to process rendered image values for regions of the rendered image in dependence on the cost indications for the corresponding sets of one or more tiles.

Abstract: A graphics processing unit (GPU) processes graphics data using a rendering space which is sub-divided into a plurality of tiles. The GPU comprises cost indication logic configured to obtain a cost indication for each of a plurality of sets of one or more tiles of the rendering space. The cost indication for a set of tile(s) is suggestive of a cost of processing the set of one or more tiles. The GPU controls a rendering complexity with which primitives are rendered in tiles based on the cost indication for those tiles. This allows tiles to be rendered in a manner that is suitable based on the complexity of the graphics data within the tiles. In turn, this allows the rendering to satisfy constraints such as timing constraints even when the complexity of different tiles may vary significantly within an image.

Abstract: A method and system for generating and shading a computer graphics image in a tile based computer graphics system is provided. Geometry data is supplied and a plurality of primitives are derived from the geometry data. One or more modified primitives are then derived from at least one of the plurality of primitives. For each of a plurality of tiles, an object list is derived including data identifying the primitive from which each modified primitive located at least partially within that tile is derived. Alternatively, the object list may include data identifying each modified primitive located at least partially within that tile. Each tile is then shaded for display using its respective object list.

Abstract: A hierarchy is a multi-level linked structure of nodes, wherein the hierarchy represents data relating to a set of one or more items to be processed. Where there are multiple input hierarchies, it may improve the efficiency of the processing of the items to merge the input hierarchies to form a merged hierarchy. The hierarchies are merged by identifying two or more sub-hierarchies within the input hierarchies which are to be merged, and determining one or more nodes of the merged hierarchy which reference nodes of the identified sub-hierarchies. The determined nodes of the merged hierarchy are stored and indications of the references between the determined nodes of the merged hierarchy and the referenced nodes of the identified sub-hierarchies are also stored. In this way, the merged hierarchy is formed for use in processing the items.

Abstract: Methods of rendering a scene in a graphics system identify a draw call within a current render and analyse the last shader in the series of shaders used by the draw call to identify any buffers that are sampled by the last shader and that are to be written by a previous render that has not yet been sent for execution on the GPU. If any such buffers are identified, further analysis is performed to determine whether the last shader samples from the identified buffers using screen space coordinates that correspond to a current fragment location and if this determination is positive, the draw call is added to data relating to the previous render and the last shader is recompiled to replace an instruction that reads data from an identified buffer with an instruction that reads data from an on-chip register.

Abstract: A graphics processing system configured to use a rendering space which is subdivided into a plurality of tiles, includes geometry processing logic having geometry transform and sub-primitive logic configured to receive graphics data of input graphics data items, and to determine transformed positions within the rendering space of one or more sub-primitives derived from the input graphics data items using a plurality of shader stages; and a tiling unit configured to generate control stream data including sub-primitive indications to indicate which of the sub-primitives are to be used for rendering each tile. The geometry processing logic is configured to write to a memory, for each instance of a pre-determined shader stage, shader stage output data comprising data output from each instance of the pre-determined shader stage used to process the received graphics data.

Abstract: A ray tracing unit is implemented in a graphics rendering system. The ray tracing unit comprises: processing logic configured to perform ray tracing operations on rays, a dedicated ray memory coupled to the processing logic and configured to store ray data for rays to be processed by the processing logic, an interface to a memory system, and control logic configured to manage allocation of ray data to either the dedicated ray memory or the memory system. Core ray data for rays to be processed by the processing logic is stored in the dedicated ray memory, and at least some non-core ray data for the rays is stored in the memory system. This allows core ray data for many rays to be stored in the dedicated ray memory without the size of the dedicated ray memory becoming too wasteful when the ray tracing unit is not in use.

Abstract: A method and system is provided for culling hidden objects in a tile-based graphics system before they are indicated in a display list for a tile. A rendering space is divided into a plurality of regions which may for example be a plurality of tiles or a plurality of areas into which one or more tiles are divided. Depth thresholds for the regions, which are used to identify hidden objects for culling, are updated when an object entirely covers a region and in dependence on a comparison between a depth value for the object and the depth threshold for the region. For example, if the depth threshold is a maximum depth threshold, the depth threshold may be updated if an object entirely covers the tile and the maximum depth value of the object is less than the maximum depth threshold.

Abstract: A method and system for generating and shading a computer graphics image in a tile based computer graphics system is provided. Geometry data is supplied and a plurality of primitives are derived from the geometry data. One or more modified primitives are then derived from at least one of the plurality of primitives. For each of a plurality of tiles, an object list is derived including data identifying the primitive from which each modified primitive located at least partially within that tile is derived. Alternatively, the object list may include data identifying each modified primitive located at least partially within that tile. Each tile is then shaded for display using its respective object list.

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: Methods of rendering a scene in a graphics system identify a draw call within a current render and analyse the last shader in the series of shaders used by the draw call to identify any buffers that are sampled by the last shader and that are to be written by a previous render that has not yet been sent for execution on the GPU. If any such buffers are identified, further analysis is performed to determine whether the last shader samples from the identified buffers using screen space coordinates that correspond to a current fragment location and if this determination is positive, the draw call is added to data relating to the previous render and the last shader is recompiled to replace an instruction that reads data from an identified buffer with an instruction that reads data from an on-chip register.

Abstract: A graphics processing system configured to use a rendering space which is subdivided into a plurality of tiles, includes geometry processing logic having geometry transform and sub-primitive logic configured to receive graphics data of input graphics data items, and to determine transformed positions within the rendering space of one or more sub-primitives derived from the input graphics data items using a plurality of shader stages; and a tiling unit configured to generate control stream data including sub-primitive indications to indicate which of the sub-primitives are to be used for rendering each tile. The geometry processing logic is configured to write to a memory, for each instance of a pre-determined shader stage, shader stage output data comprising data output from each instance of the pre-determined shader stage used to process the received graphics 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 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: A method and system is provided for culling hidden objects in a tile-based graphics system before they are indicated in a display list for a tile. A rendering space is divided into a plurality of regions which may for example be a plurality of tiles or a plurality of areas into which one or more tiles are divided. Depth thresholds for the regions, which are used to identify hidden objects for culling, are updated when an object entirely covers a region and in dependence on a comparison between a depth value for the object and the depth threshold for the region. For example, if the depth threshold is a maximum depth threshold, the depth threshold may be updated if an object entirely covers the tile and the maximum depth value of the object is less than the maximum depth threshold.

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: Methods and tessellation modules for tessellating a patch to generate tessellated geometry data representing the tessellated patch. Received geometry data representing a patch is processed to identify tessellation factors of the patch. Based on the identified tessellation factors of the patch, tessellation instances to be used in tessellating the patch are determined. The tessellation instances are allocated amongst a plurality of tessellation pipelines that operate in parallel, wherein a respective set of one or more of the tessellation instances is allocated to each of the tessellation pipelines, and wherein each of the tessellation pipelines generates tessellated geometry data associated with the respective allocated set of one or more of the tessellation instances.

Abstract: Methods and graphics processing modules for rendering a stereoscopic image including left and right images of a three-dimensional scene. Geometry is processed in the scene to generate left data for use in displaying the left image and right data for use in displaying the right image. Disparity is determined between the left and right data by comparing the generated left data and the generated right data used in displaying the stereoscopic image. In response to identifying at least a portion of the left data and the right data as non-disparate, a corresponding portion of the left image and the right image is commonly processed (e.g. commonly rendered or commonly stored). In response to identifying at least a portion of the left data and the right data as disparate, a corresponding portion of the left image and the right image is separately processed (e.g. separately rendered or separately stored).

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