Advanced Micro Devices Corporation

Saad Arrabi

Todd Martin

Mangesh P Nijasure

Vishrut Vaibhav

A graphics pipeline includes a tessellator stage having a sub-patch distributor and a plurality of tessellators. The sub-patch distributor divides an input patch into a plurality of sub-primitive groups, with the primitive group limit governing the maximum permissible size for a given group of sub-primitives to be assigned to a tessellator. The sub-patch distributor recursively identifies a plurality of regions of the input patch, with the size and number of primitives of each region based on the specified primitive group limit. The sub-patch distributor assigns different regions to different sub-patch groups and distributes the sub-patch groups among the plurality of tessellators.

Tessellator sub-patch distribution based on group limits

Techniques for removing reset indices from, and identifying primitives in, an index stream that defines a set of primitives to be rendered, are disclosed. The index stream may be specified by an application program executing on the central processing unit. The technique involves classifying the primitive topology for the index stream as either requiring an offset-based technique or requiring a non-offset-based technique. This classification is done by determining whether, according to the primitive topology, each subsequent index can form a primitive with prior indices (e.g., line strip, triangle strip). If each subsequent index can form a primitive with prior indices, then the technique used is the non-offset-based technique. If each subsequent index does not form a primitive with prior indices, but instead at least two indices are required to form a new primitive (e.g., line list, triangle list), then the technique used is the offset-based technique.

Identifying primitives in input index stream

Identifying primitives in input index system

Techniques for removing duplicate indices from an index stream are disclosed. The techniques involve dividing the indices into chunks. For any particular chunk, the techniques involve examining each index in the chunk to determine whether a 'match' exists for that index within a reuse depth sliding window. The reuse depth sliding window includes a fixed number of indices immediately prior to the index being examined for a match. If a match exists, then the index is marked as non-unique and is assigned a position value equal to the position value of the matching index. If a match does not exist, then the index is marked as unique and assigned the next available position value for the chunk. After assigning position values to indices in a chunk, the indices in the chunk are transmitted to a vertex shader stage for processing in the order indicated by the position values.

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Saad Arrabi