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# Pathfinder 3
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Pathfinder 3 is a fast, practical, GPU-based rasterizer for fonts and vector graphics using OpenGL
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and OpenGL ES 3.0+.
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2017-10-06 22:55:28 -04:00
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Please note that Pathfinder is under heavy development and is incomplete in various areas.
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The project features:
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* High quality antialiasing. Pathfinder can compute exact fractional trapezoidal area coverage on a
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per-pixel basis for the highest-quality antialiasing possible (effectively 256xAA).
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* Fast CPU setup, making full use of parallelism. Pathfinder 3 uses the Rayon library to quickly
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perform a CPU tiling prepass to prepare vector scenes for the GPU. This prepass can be pipelined
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with the GPU to hide its latency.
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* Fast GPU rendering, even at small pixel sizes. Even on lower-end GPUs, Pathfinder typically
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matches or exceeds the performance of the best CPU rasterizers. The difference is particularly
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pronouced at large sizes, where Pathfinder regularly achieves multi-factor speedups. All shaders
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have no loops and minimal branching.
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* Advanced font rendering. Pathfinder can render fonts with slight hinting and can perform subpixel
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antialiasing on LCD screens. It can do stem darkening/font dilation like macOS and FreeType in
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order to make text easier to read at small sizes. The library also has support for gamma
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correction.
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* Support for SVG. Pathfinder 3 is designed to efficiently handle workloads that consist of many
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overlapping vector paths, such as those commonly found in SVG and PDF files. It can perform
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occlusion culling, which often results in dramatic performance wins over typical software
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renderers that use the painter's algorithm. A simple loader that leverages the `resvg` library
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to render a subset of SVG is included, so it's easy to get started.
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* 3D capability. Pathfinder can render fonts and vector paths in 3D environments without any loss
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in quality. This is intended to be useful for vector-graphics-based user interfaces in VR, for
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example.
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* Lightweight. Unlike large vector graphics packages that mix and match many different algorithms,
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Pathfinder 3 uses a single, simple technique. It consists of a set of modular crates, so
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applications can pick and choose only the components that are necessary to minimize dependencies.
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* Portability to most GPUs manufactured in the last decade, including integrated and mobile GPUs.
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Geometry, tessellation, and compute shader functionality is not required.
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## Building
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Pathfinder 3 is a set of modular packages, allowing you to choose which parts of the library you
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need. An SVG rendering demo, written in Rust, is included, so you can try Pathfinder out right
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away. It also provides an example of how to use the library. (Note that, like the rest of
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Pathfinder, the demo is under heavy development and has known bugs.)
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Running the demo is as simple as:
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$ cd demo/native
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$ RUSTFLAGS="-C target-cpu=native" cargo run --release
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On macOS, it is recommended that you force the use of the integrated GPU, as issues with Apple's
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OpenGL drivers may limit performance on discrete GPUs. You can use
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[gfxCardStatus.app](https://gfx.io/) for this.
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## Authors
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The primary author is Patrick Walton (@pcwalton), with contributions from the Servo development
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community.
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2017-12-19 22:11:12 -05:00
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The logo was designed by Jay Vining.
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Contributors to Pathfinder are expected to abide by the same Code of Conduct as Rust itself.
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## License
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Pathfinder is licensed under the same terms as Rust itself. See `LICENSE-APACHE` and `LICENSE-MIT`.
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Material Design icons are copyright Google Inc. and licensed under the Apache 2.0 license.
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