Conversion of dashed strokes into quadratic bèzier segment sequences

Abstract

One embodiment of the present invention sets forth a technique for converting dashed strokes into quadratic Bèzier segment sequences. Path rendering with stroking and dashing may be accelerated when a graphics processing unit or other processor is configured to subdivide quadratic Bèzier segments based on the remaining distance for a current dash pattern element and the arc length of the current quadratic Bèzier path segment to generate “on” dash pattern segments. Each “on” dash pattern segment is then bounded by a conservative geometric hull. A point containment technique is then used to identify pixels within each conservative geometric hull that are within half of the stroke width of any point along a path to be stroked.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority benefit to United States provisional patent application titled, “Path Rendering,” filed on May 21, 2010 and having Ser. No. 61 / 347,359 (Attorney Docket Number NVDA / SC-10-0110-US0). This related application is also hereby incorporated by reference in its entirety.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention generally relates to graphics processing and more specifically to converting dashed strokes into quadratic Bèzier segment sequences.[0004]2. Description of the Related Art[0005]Path rendering is a style of resolution-independent two-dimensional (2D) rendering, often called “vector graphics,” that is the basis for a number of important rendering standards such as PostScript, Java 2D, Apple's Quartz 2D, OpenVG, PDF, TrueType fonts, OpenType fonts, PostScript fonts, Scalable Vector Graphics (SVG) web format, Microsoft's Silverlight and Adobe Flash for interactive web...

AI Technical Summary

Benefits of technology

[0028]One embodiment of the present invention sets forth a technique converting dashed strokes into quadratic Bèzier segment sequences. Path rendering with stroking and dashing may be accelerated when a graphics processing unit or other processor is configured to subdivide quadratic Bèzier segments based on a dash pattern. Each subdivided quadratic Bèzier segment is then bounded by a conservative geometric hull. A point containment technique is then used identify pixels within each conservative geometric hull that are within half of the stroke width of any point along a path to be stroked.

Problems solved by technology

This property does not generally hold for tessellated versions of stroked paths where the process of subdividing curved edges and introducing tessellated triangles typically increases the size of the resulting geometry set considerably.

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