Abstract: A tag buffer implements a tag buffer stage of a rasterization phase in a tile-based rendering graphics processing system having a rendering space sub-divided into a plurality of tiles to which primitives can be associated. A buffer stores an identifier that identifies a visible primitive fragment at each sample position of a tile of the plurality of tiles. A look-up table stores an entry for transformed primitive blocks that indicates whether the tag buffer has received information identifying a primitive fragment associated with that transformed primitive block.

Abstract: A ray tracing unit implemented in a graphics rendering system includes 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: 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: 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 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 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: 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 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: 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 graphics processor architecture provides for scan conversion and ray tracing approaches to visible surface determination as concurrent and separate processes. Surfaces can be identified for shading by scan conversion and ray tracing. Data produced by each can be normalized, so that instances of shaders, being executed on a unified shading computation resource, can shade surfaces originating from both ray tracing and rasterization. Such resource also may execute geometry shaders. The shaders can emit rays to be tested for intersection by the ray tracing process. Such shaders can complete, without waiting for those emitted rays to complete. Where scan conversion operates on tiles of 2-D screen pixels, the ray tracing can be tile aware, and controlled to prioritize testing of rays based on scan conversion status. Ray population can be controlled by feedback to any of scan conversion, and shading.

Abstract: Systems and methods of geometry processing, for rasterization and ray tracing processes provide for pre-processing of source geometry, such as by tessellating or other procedural modification of source geometry, to produce final geometry on which a rendering will be based. An acceleration structure (or portion thereof) for use during ray tracing is defined based on the final geometry. Only coarse-grained elements of the acceleration structure may be produced or retained, and a fine-grained structure within a particular coarse-grained element may be Produced in response to a collection of rays being ready for traversal within the coarse grained element. Final geometry can be recreated in response to demand from a rasterization engine, and from ray intersection units that require such geometry for intersection testing with primitives. Geometry at different resolutions can be generated to respond to demands from different rendering components.

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: Methods and apparatus for generating a data structure for storing primitive data for a number of primitives and vertex data for a plurality of vertices, wherein each primitive is defined with reference to one or more of the plurality of vertices. The vertex data comprises data for more than one view, such as a left view and a right view, with vertex parameter values for a first group of vertex parameters being stored separately for each view and vertex parameter values for a second, non-overlapping group of vertex parameters being stored only once and used when rendering either or both views.

Abstract: A method and system for culling a patch of surface data from one or more tiles in a tile based computer graphics system. A rendering space is divided into a plurality of tiles and a patch of surface data read. Then, at least a portion of the patch is analysed to determine data representing a bounding depth value evaluated over at least one tile. This may comprise tessellating the patch of surface data to derive a plurality of tessellated primitives and analysing at least some of the tessellated primitives. For each tile within which the patch is located, the data representing the bounding depth value is then used to determine whether the patch is hidden in the tile, and at least a portion of the patch is rendered, if the patch is determined not to be hidden in at least one tile.

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 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: A graphics processor architecture provides for scan conversion and ray tracing approaches to visible surface determination as concurrent and separate processes. Surfaces can be identified for shading by scan conversion and ray tracing. Data produced by each can be normalized, so that instances of shaders, being executed on a unified shading computation resource, can shade surfaces originating from both ray tracing and rasterization. Such resource also may execute geometry shaders. The shaders can emit rays to be tested for intersection by the ray tracing process. Such shaders can complete, without waiting for those emitted rays to complete. Where scan conversion operates on tiles of 2-D screen pixels, the ray tracing can be tile aware, and controlled to prioritize testing of rays based on scan conversion status. Ray population can be controlled by feedback to any of scan conversion, and shading.