Pathfinder 3

Pathfinder 3 is a fast, practical, GPU-based rasterizer for fonts and vector graphics using OpenGL 3.0+, OpenGL ES 3.0+, WebGL 2, and Metal.

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. You can quickly add vector rendering to any Rust or C/C++ app with it. The library is available on crates.io. See examples/canvas_minimal for a small example of usage.

Demos

Demo app sources are available in demo/native. Simply run:

$ cd demo/native
$ cargo run --release

A variety of small examples are also available to get you up and running quickly. For example, you can run the canvas_nanovg example like so:

$ cd examples/canvas_nanovg
$ cargo run --release

Features

The project features:

• Rust and C bindings, for easy embedding in your own applications regardless of programming language. (Note that the C bindings are currently less complete; pull requests are welcome!)

• GPU compute-based rendering, where available. Pathfinder has two rendering modes: D3D11, which is based on compute, and D3D9, which is based on hardware rasterization. (Note that these names are purely convenient ways to refer to hardware levels: the project doesn't have a proper Direct3D backend yet.) In the D3D11 mode, Pathfinder uses compute shaders to achieve large reductions in CPU usage and overall better performance than what the built-in GPU rasterization hardware can provide.

• Fast CPU setup if needed, making full use of parallelism. If the D3D9 backend is in use, Pathfinder performs the tiling step using SIMD and Rayon in order to get as much parallelism out of the CPU as possible. (In the D3D11 backend, these steps are done on GPU instead.) The CPU step can be pipelined with the GPU to hide its latency.

• Fast GPU rendering, even at small pixel sizes. Even on lower-end GPUs, Pathfinder often matches or exceeds the performance of the best CPU rasterizers. The difference is particularly pronounced at large sizes, where Pathfinder regularly achieves multi-factor speedups.

• High quality antialiasing. Pathfinder can compute exact fractional trapezoidal area coverage on a per-pixel basis for the highest-quality antialiasing possible (effectively 256xAA).

• 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 complex SVG and PDF files. It performs tile-based 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. Pathfinder is designed first and foremost for simplicity and generality instead of a large number of specialized fast paths. 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. Any GPU capable of Direct3D 9/OpenGL 3.0/WebGL 2.0 should be able to run Pathfinder. Currently, backends are available for OpenGL, OpenGL ES, Metal, and WebGL.

Building

Pathfinder can be used from either Rust or C/C++. See the appropriate section below.

Rust

Simply run cargo build --release at top level to build all the crates. Pathfinder is a set of modular crates, allowing you to select only the parts of the library you need and omit the rest. The libraries are available on crates.io with the pathfinder_ prefix (e.g. pathfinder_canvas), but you may wish to use the main branch for the latest features and bug fixes.

C

The C bindings use cargo-c. Install cargo-c with cargo install cargo-c, and then use a command like:

$ cargo cinstall --destdir=/tmp/pathfinder-destdir --manifest-path c/Cargo.toml
$ sudo cp -a /tmp/pathfinder-destdir/* /

The resulting library is usable via pkg-config as pathfinder. For examples of use, see the examples in the examples/ directory beginning with c_.

cargo-c has a variety of other options such as --prefix, which may be useful for packagers.

Community

There's a Matrix chat room available at #pathfinder:mozilla.org. If you're on the Mozilla Matrix server, you can search for Pathfinder to find it. For more information on connecting to the Matrix network, see this wiki.mozilla.org page.

The entire Pathfinder community, including the chat room and GitHub project, is expected to abide by the same Code of Conduct that the Rust project itself follows. (At the moment, the authors will handle violations.)

Build status

Authors

The primary author is Patrick Walton (@pcwalton), with contributions from the Servo development community.

The logo was designed by Jay Vining.

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.

lib.rs:

An OpenGL implementation of the device abstraction.