Abstract: When an alpha test is performed as part of the rendering process in a multisampled graphics processing pipeline, rather than taking the single alpha value initially defined for each fragment an individual alpha value is generated in respect of each of covered sampling position that the fragment in question is being used to render. The individual alpha values estimated for each sample position are then individually compared with a threshold alpha value defined for the alpha test, and the result of this alpha test comparison is used to decide either keep or discard the sample position from further processing.

Abstract: A graphics processing platform includes a rasteriser 50 that receives primitives representing an image to be displayed for processing. The rasteriser 50 determines which sets of sampling points of the image include sampling points that are covered by a given primitive, and then generates a fragment for rendering for each set of sampling points found to include a sampling point that is covered by the primitive and passes those fragments to a renderer 51 for rendering. The renderer 51 carries out rendering operations on the fragments that it receives, and stores the rendered fragment data in tile buffers 52. The rendered fragment data is stored in multiple copies in the appropriate sample positions in the tile buffers 52, so as to provide a separate set of fragment data for each individual sample position taken of the image. The data from the tile buffers 52 is input to a downsampling unit 53, and thence output to a frame buffer 54 of a display device 55 for display.

Abstract: A graphics processor 1 includes after its tile rendering logic 40, a transaction elimination unit 5 that includes data block generation logic 41 and block comparison logic 43. The block generation logic 41 generates data blocks from the rendered tiles produced by the tile rendering logic 40. The data blocks are then stored in buffers 42. Comparison logic 43 then compares a new data block with the previous data block (which will already be stored in the buffers 42), and generates an output metadata bit indicating whether the blocks can be considered to be the same or not, on the basis of the comparison. The meta-data output bits are stored appropriately in a meta-data bitmap 45 in main memory 2 that is associated with the output data array in question. If the blocks are determined to be different by the comparison logic then the new data block is written from the buffers 42 to the frame buffer 44 in the main memory 2.

Abstract: A graphics processing platform includes a rasteriser 50 that receives primitives representing an image to be displayed for processing. The rasteriser 50 determines which sets of sampling points of the image include sampling points that are covered by a given primitive, and then generates a fragment for rendering for each set of sampling points found to include a sampling point that is covered by the primitive and passes those fragments to a renderer 51 for rendering. The renderer 51 carries out rendering operations on the fragments that it receives, and stores the rendered fragment data in tile buffers 52. The rendered fragment data is stored in multiple copies in the appropriate sample positions in the tile buffers 52, so as to provide a separate set of fragment data for each individual sample position taken of the image. The data from the tile buffers 52 is input to a downsampling unit 53, and thence output to a frame buffer 54 of a display device 55 for display.

Abstract: In a tile-based graphics processor, primitive lists (bins) are prepared for 2×2 blocks of tiles 40. The processor also determines and stores for each primitive in a bin, distribution information indicating the distribution of the primitive within the set of tiles that the bin corresponds to. Thus a primitive 42 that is found by its bounding box 43 to reside in two of the four tiles that make up the set of 2×2 tiles 40 is also associated with a tile coverage bitmap of the form “0101” to indicate that it lies in tiles “1” and “3” of the 2×2 group of tiles 40. The graphics processor uses the coverage bitmap (information) to determine whether a primitive should be processed for the tile currently being processed.

Abstract: In a graphics processing system, when a 16× sampling mask is used for sampling the image to be displayed, fragments are generated and rendered to generate rendered fragment data for each covered sampling position. However, the 16× sampling mask (81, 84, 86, 89) can be divided into a two-level hierarchy for the purpose of associating its sampling points with fragments that are to be rendered, namely a first level in which a fragment (82, 85, 88) is associated with all 16 sampling points of the 16× sampling mask, and a second level in which a fragment (91, 92) is only associated with four sampling points of the 16× sampling mask.

Abstract: A smooth curve is represented in a graphics texture by setting the texels that are inside the curve 80 to a value greater than a predetermined threshold value for the curve 80 and the texels that are outside the curve 80 to a value of less than the threshold value for the curve 80 (or vice-versa). Such representations of two smooth curves 80, 81 are packed into a single graphics texture (the same texel space) 82 by giving each curve 80, 81 a different threshold value, setting the texel values so that they are appropriately valued with respect to each curve's threshold value, and ensuring that the positions of the threshold value contours of the two curves do not actually overlap each other in the texture.

Abstract: An input stroked curve 1 that is received by a graphics processing system can be rendering using at least two, and preferably more, rendering processes that are available for use by the system. The process or processes that are used for rendering the received stroked curve 1 are selected based on whether the input stroked curve comprises one or more regions having a particular characteristic or characteristics, e.g. whether the input stroked curve 1 comprises one or more self-overlapping regions. Preferably, the at least two rendering processes are each capable of correctly rendering different sets of stroked curves. Furthermore, the least two rendering process preferably differ in the processing burden that they place on the graphics processing system.

Abstract: When rendering a stroked curve for display in a graphics processing system, an input stroked curve 1 defined in user space 2 is received by the system. The portion of a canonical space 5 that corresponds to the received stroked curve 1 is determined by determining the portion of a canonical curve 12 defined in the canonical space 5 that corresponds to the received stroked curve 1. Then, for each of a plurality of sampling points within one or more primitives 4 that are generated to cover the received stroked curve 1? following its projection into surface space 3, it is determined whether a corresponding location in canonical space 5 (to the sampling point in surface space 3) is within the portion of the canonical space that corresponds to the received stroked curve, e.g. by looking up suitable information that has been stored (in advance) in one or more graphics textures. Data for rendering the received stroked curve 1 (e.g.

Abstract: A smooth curve is represented in a graphics texture by setting the texels that are inside the curve 1 to a value greater than a predetermined threshold value and the texels that are outside the curve 1 to a value less than the threshold value (or vice-versa). The texture value returned for a sampled position can thus be used to determine whether the sampled position should be treated as being inside the curve 1 or not. The texture is optimised for sampling using bi-linear filtering.