JoltC

JoltC

C wrapper for Jolt Physics 5.x.

Currently a work in progress. Bindings contain functions that we've needed as part of our game or the Rust bindings we're working on in jolt-rust.

The JoltC directory contains headers for the C interface that you can bind to.

The JoltCImpl directory contains the C++ implementation of the C interface and serves as the glue between the C++ and C code.

Goals

1. Sound C wrapper around current version of Jolt Physics
   • We avoid relying on unspecified C++ type layout, which means reflecting those types as opaque handles.
   • We always assert identical layout when creating FFI-compatible versions of C++ types in cases where it makes sense.
2. Headers suitable for usage in automatic binding generation tools (i.e. Rust bindgen, LuaJIT FFI)

Building

Use CMake:

# Configure the build
cmake -B build

# Optionally, you can enable double precision, or make ObjectLayer use 32 bits
# We aim to support most of the configuration of Jolt's C++ API.
cmake -B build -DDOUBLE_PRECISION=ON -DOBJECT_LAYER_BITS=32

# Build
cmake --build build

Hello, world!

A port of Jolt's "HelloWorld" example is provided in HelloWorld/main.cpp.

Jolt's RefTarget Types

Jolt has internal reference counting for a few types along with good documentation about handling them in C++. This interface to Jolt does not have a generic Ref/RefConst wrapper, so it's important to be conscious of ref counts when handling these types.

Just like Jolt, this library will return those objects with a reference count of 0. Jolt APIs that accept these types will take ownership of the given value and increment the reference count.

You can use JPC_{type}_AddRef and JPC_{type}_Release, where {type} is the type that directly inherits from RefTarget<{type}>, to add or release references. For example, for FixedConstraint, use JPC_Constraint_AddRef to add a new reference.

Other C Wrappers

Other C wrappers for Jolt Physics include:

• "JoltC", part of the zphysics Zig library started by Michal Ziulek
• "JoltC", part of the jolt-rs Rust library started by cohaereo and a fork of the zphysics C wrapper
• "joltc", part of the JoltPhysicsSharp C# library started by Amer Koleci

The goal of this project is to be a C wrapper around Jolt Physics that is not part of a larger binding project and to eliminate major sources of undefined behavior. It's intended to be useful for any other language-specific bindings, but naturally these bindings were born out of the goal of creating Rust bindings to Jolt Physics.

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.