Changes from MuJoCo

MuJoCo-rs tries to follow MuJoCo’s API with a few exceptions that make it more Rust-idiomatic, safer, and easier to use.

Methods

One of the changes from the MuJoCo C API is methods. Since most MuJoCo functions directly correspond to some struct, we turned those functions into methods on appropriate structs, while leaving the more general functions wrapped in idiomatic Rust function wrappers.

For example, the function mujoco_c::mj_loadXML is replaced with the method MjModel::from_xml, while the more general function mujoco_c::mju_rayGeom is replaced with utility::mju_ray_geom.

Structs

Most of MuJoCo’s structs are plain data structs. In Rust, we mostly keep them as-is, renaming them to PascalCase. Structs with heap-allocated data are wrapped in safe Rust types that automatically manage memory and provide safe attribute access.

Attributes that are not directly exposed can be accessed via .ffi() and unsafe .ffi_mut() methods. For more details, see Interface to C API.

Additionally, MjData and MjModel provide Attribute views to specific item types (joint, body, geom, etc.).