92 lines
4.4 KiB
Markdown
92 lines
4.4 KiB
Markdown
# Pathfinder 3
|
|
|
|
Pathfinder 3 is a fast, practical, GPU-based rasterizer for fonts and vector graphics using OpenGL
|
|
and OpenGL ES 3.0+.
|
|
|
|
Please note that Pathfinder is under heavy development and is incomplete in various areas.
|
|
|
|
## Quick start
|
|
|
|
Pathfinder contains a library that implements a subset of the
|
|
[HTML canvas API](https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API). You can quickly add
|
|
vector rendering to any Rust app with it. See the `examples/canvas_minimal` for a small example of
|
|
usage.
|
|
|
|
This example app requires SDL 2; see the "Building" section below for information on getting it up
|
|
and running.
|
|
|
|
## Features
|
|
|
|
The project features:
|
|
|
|
* High quality antialiasing. Pathfinder can compute exact fractional trapezoidal area coverage on a
|
|
per-pixel basis for the highest-quality antialiasing possible (effectively 256xAA).
|
|
|
|
* Fast CPU setup, making full use of parallelism. Pathfinder 3 uses the Rayon library to quickly
|
|
perform a CPU tiling prepass to prepare vector scenes for the GPU. This prepass can be pipelined
|
|
with the GPU to hide its latency.
|
|
|
|
* Fast GPU rendering, even at small pixel sizes. Even on lower-end GPUs, Pathfinder typically
|
|
matches or exceeds the performance of the best CPU rasterizers. The difference is particularly
|
|
pronouced at large sizes, where Pathfinder regularly achieves multi-factor speedups. All shaders
|
|
have no loops and minimal branching.
|
|
|
|
* Advanced font rendering. Pathfinder can render fonts with slight hinting and can perform subpixel
|
|
antialiasing on LCD screens. It can do stem darkening/font dilation like macOS and FreeType in
|
|
order to make text easier to read at small sizes. The library also has support for gamma
|
|
correction.
|
|
|
|
* Support for SVG. Pathfinder 3 is designed to efficiently handle workloads that consist of many
|
|
overlapping vector paths, such as those commonly found in SVG and PDF files. It can perform
|
|
occlusion culling, which often results in dramatic performance wins over typical software
|
|
renderers that use the painter's algorithm. A simple loader that leverages the `resvg` library
|
|
to render a subset of SVG is included, so it's easy to get started.
|
|
|
|
* 3D capability. Pathfinder can render fonts and vector paths in 3D environments without any loss
|
|
in quality. This is intended to be useful for vector-graphics-based user interfaces in VR, for
|
|
example.
|
|
|
|
* Lightweight. Unlike large vector graphics packages that mix and match many different algorithms,
|
|
Pathfinder 3 uses a single, simple technique. It consists of a set of modular crates, so
|
|
applications can pick and choose only the components that are necessary to minimize dependencies.
|
|
|
|
* Portability to most GPUs manufactured in the last decade, including integrated and mobile GPUs.
|
|
Geometry, tessellation, and compute shader functionality is not required.
|
|
|
|
## Building
|
|
|
|
Pathfinder 3 is a set of modular packages, allowing you to choose which parts of the library you
|
|
need. An SVG rendering demo, written in Rust, is included, so you can try Pathfinder out right
|
|
away. It also provides an example of how to use the library. (Note that, like the rest of
|
|
Pathfinder, the demo is under heavy development and has known bugs.)
|
|
|
|
Running the demo is as simple as:
|
|
|
|
$ cd demo/native
|
|
$ RUSTFLAGS="-C target-cpu=native" cargo run --release
|
|
|
|
The SDL 2 library requires some additional manual installation steps. Follow the
|
|
[`rust-sdl2` installation instructions](https://github.com/Rust-SDL2/rust-sdl2#sdl20-development-libraries) to make sure the libraries are installed. Note that SDL2 is
|
|
only required to run the demo; Pathfinder itself has no dependency on the library.
|
|
|
|
On macOS, it is recommended that you force the use of the integrated GPU, as issues with Apple's
|
|
OpenGL drivers may limit performance on discrete GPUs. You can use
|
|
[gfxCardStatus.app](https://gfx.io/) for this. See the
|
|
[wiki](https://github.com/pcwalton/pathfinder/wiki/GPU-driver-compatibility) for more information
|
|
on GPU compatibility issues.
|
|
|
|
## Authors
|
|
|
|
The primary author is Patrick Walton (@pcwalton), with contributions from the Servo development
|
|
community.
|
|
|
|
The logo was designed by Jay Vining.
|
|
|
|
Contributors to Pathfinder are expected to abide by the same Code of Conduct as Rust itself.
|
|
|
|
## License
|
|
|
|
Pathfinder is licensed under the same terms as Rust itself. See `LICENSE-APACHE` and `LICENSE-MIT`.
|
|
|
|
Material Design icons are copyright Google Inc. and licensed under the Apache 2.0 license.
|