Nvidia Corporation

Mark J Kilgard

Cass Watson Everitt

Patrick Richard Brown

Robert Steven Glanville

Jeffrey A Bolz

Christopher T Dodd

John Erik Lindholm

Rui Manuel Bastos

William P Newhall, Jr

Rui Bastos

Matthew Nicholas Papakipos

Henry Packard Moreton

Edward Anthony Hutchins

Eric Sovelen Werness

Barthold B Lichtenbelt

Michael I Gold

Jason Sams

Jerome Francis Duluk, Jr

Jonah Matthew Alben

Dale L Kirkland

Eric Brian Lum

David B Kirk

Michael J M Toksvig

Douglas A Voorhies

Paolo Enrique Sabella

Christopher D S Donham

William R Mark

Christian Rouet

John F Spitzer

Rev Lebaredian

Gary C King

Kurt Barton Akeley

Christian Amsinck

Johnny S Rhoades

Matthew J Craighead

William Craig McKnight

Wei-Chao Chen

Pierre Souillot

Jason R Allen

Joseph Detmer

Don Bittel

Charles M Flaig

Brian Kretzler

The disclosure introduces polar stroking for representing paths. A system, method, and apparatus are disclosed for representing and rendering stroked paths employing polar stroking. In one example, a method of approximating a path is provided that includes: (1) evaluating, in parallel, multiple links of a path, wherein each link of the multiple links is evaluated in steps based on tangent angle changes of the link, and (2) providing a polar stroked representation of the path employing the steps. A computing system for rendering is also provided. In one example, the computing system includes one or more processing units to perform one or more operations including generating, in parallel, a polar stroked representation of individual links of a path, and rendering a stroked tessellation of the path based on the polar stroked representations of the individual links.

Polar stroking for vector graphics

The disclosure provides computer systems for processing paths and a renderer that generates a stroked tessellation of a path. A data structure for processing the paths can be used, wherein the data structure is an array of indexed links that compactly encode a path. The position of one or more index values, such as a null index value, within an indexed link can encode a link's type. In one example, the computer system for processing links of a path includes one or more processing units to perform one or more operations including: (1) analyzing a data structure that encodes a link of a path, the data structure having multiple indices that refer to a control point coordinate array corresponding to the link, and (2) determining a type of the link based on a presence of at least one index null value for at least one of the indices.

Method and system for unified encoding of path segments, caps, and joins for path stroking

The disclosure provides methods of encoding a path, a stroking system for paths, a renderer that generates a stroked tessellation of a path, and a method of determining a type of link of a path from a data structure. The data structure can be an array of indexed links that compactly encode a path. The position of one or more index values, such as a null index value, within an indexed link can encode the link's type. In one example, a method of encoding includes: (1) receiving a path having multiple links, wherein the links include at least one segment and at least one junction, and (2) generating an encoded path by encoding the links based on positional information of the links, wherein the encoding employs a same data structure for each of the links.

The disclosure introduces polar stroking for representing paths. A system, method, and apparatus are disclosed for representing and rendering stroked paths employing polar stroking. In one example, a method of approximating a link of a path is provided that includes: (1) determining tangent angle changes of a link of a path, (2) evaluating the link in steps based on the tangent angle changes, and (3) providing a polar stroked representation of the link employing the steps, wherein the evaluating is performed non-recursively. A polar stroking system is also disclosed. In one example, the polar stroking system includes: (1) a path processor configured to decompose a path into links, and (2) a polar stroking processor configured to determine polar stroking intermediates of the links from a characterization of the links and generate, employing the polar stroking intermediates, a polar stroked representation for each of the links.

One embodiment of the present invention includes techniques for rasterizing primitives that include edges shared between paths. For each edge, a rasterizer unit selects and applies a sample rule from multiple sample rules. If the edge is shared, then the selected sample rule causes each group of coverage samples associated with a single color sample to be considered as either fully inside or fully outside the edge. Consequently, conflation artifacts caused when the number of coverage samples per pixel exceeds the number of color samples per pixel may be reduced. In prior-art techniques, reducing such conflation artifacts typically involves increasing the number of color samples per pixel to equal the number of coverage samples per pixel. Advantageously, the disclosed techniques enable rendering using algorithms that reduce the ratio of color to coverage samples, thereby decreasing memory consumption and memory bandwidth use, without causing conflation artifacts associated with shared edges.

Stencil-then-cover path rendering with shared edges

One embodiment of the present invention sets forth a technique for improving path rendering on computer systems with an available graphics processing unit. The technique involves reducing complex path objects to simpler geometric objects suitable for rendering on a graphics processing unit. The process involves a central processing unit 'baking' a set of complex path rendering objects to generate a set of simpler graphics objects. A graphics processing unit then renders the simpler graphics objects. This division of processing load can advantageously yield higher overall rendering performance.

Baking path rendering objects into compact and efficient memory representations

One embodiment of the present invention includes techniques for rasterizing geometries. First, a processing unit defines a bounding primitive that covers the geometry and does not include any internal edges. If the bounding primitive intersects any enabled clip plane, then the processing unit generates fragments to fill a current viewport. Alternatively, the processing unit generates fragments to fill the bounding primitive. Because the rasterized region includes no internal edges, conflation artifacts caused when the number of coverage samples per pixel exceeds the number of color samples per pixel may be reduced. In prior-art techniques, reducing such conflation artifacts typically involves increasing the number of color samples per pixel to equal the number of coverage samples per pixel. Consequently, the disclosed techniques enable rendering using algorithms that reduce the ratio of color to coverage samples, thereby decreasing memory consumption and memory bandwidth use, without causing conflation artifacts associated with cover geometries.

Rendering cover geometry without internal edges

A graphics processing pipeline within a parallel processing unit (PPU) is configured to perform path rendering by generating a collection of graphics primitives that represent each path to be rendered. The graphics processing pipeline determines the coverage of each primitive at a number of stencil sample locations within each different pixel. Then, the graphics processing pipeline reduces the number of stencil samples down to a smaller number of color samples, for each pixel. The graphics processing pipeline is configured to modulate a given color sample associated with a given pixel based on the color values of any graphics primitives that cover the stencil samples from which the color sample was reduced. The final color of the pixel is determined by downsampling the color samples associated with the pixel.

Target independent rasterization with multiple color samples

One embodiment of the present invention sets forth a technique for rendering anti-aliased paths by first generating an alpha buffer representing coverage data. To generate the alpha buffer, jittered versions of the rendered path are rendered and corresponding stencil buffers indicating sub-pixel samples of the path that should be covered are generated. After each stencil buffer is generated, the jittered path is rasterized to convert the sub-pixel coverage into coverage weights that are stored in the alpha component of a frame buffer. As each jittered path is rasterized, the coverage weights are accumulated. Finally, geometry representing the union of the jittered versions of the path is rendered to shade pixels based on the accumulated coverage weights. The anti-aliased rendered paths may be filled or stroked without tessellating the paths.

Jittered coverage accumulation path rendering

A technique for efficiently rendering path images tessellates path contours into triangle tans comprising a set of representative triangles. Topology of the set of representative triangles is then optimized for greater rasterization efficiency by applying a flip operator to selected triangle pairs within the set of representative triangles. The optimized triangle pairs are then rendered using a path rendering technique, such as stencil and cover.

Optimizing triangle topology for path rendering

Stencil then cover path rendering with shared edges

One embodiment of the present invention sets forth a technique for rendering paths by first generating a stencil buffer indicating pixels of the path that should be covered and then covering the path. The paths may be filled or stroked without tessellating the paths. Path rendering may be accelerated when a graphics processing unit or other processor that is configured to perform operations to generate the stencil buffer and cover the path to fill or stroke the path. When the paths are rendered in a top-to-bottom (front-to-back) order, an opacity stencil may be generated and used to avoid determining path coverage and shading for pixels that are opaque.

Top-to bottom path rendering with opacity testing

One embodiment of the present invention sets forth a technique for rendering paths by first generating a stencil buffer indicating pixels of the path that should be covered and then covering the path. The paths may be filled or stroked without tessellating the paths. Path rendering may be accelerated when a graphics processing unit or other processor that is configured to perform operations to generate the stencil buffer and cover the path to fill or stroke the path.

Path rendering by covering the path based on a generated stencil buffer

Growing community of inventors

Cupertino, CA, United States of America

Mark J Kilgard