Perro Engine

Perro is an experimental, open-source game engine written in Rust. With a focus on performance and simplicity without sacrificing either.

Philosophy

• Simple To Learn: start with scenes, nodes, and Rust scripts without large registration steps or boilerplate.
• Flexible To Use: reduces borrow-checker friction with direct APIs and scoped closures for mutable access. Separating state from script behavior prevents runtime borrow failures.
• Fast In Release: nodes and scripts are laid out for efficient node and state access, all resources are statically baked in release for efficient and quick retrieval

Design Goals

• Full Game-Making Scope: 2D, 3D, and UI all matter. Perro aims to support both 2D and 3D performantly, with high frame rates and a workflow that stays simple.
• Simple Start: get first scene and script running quickly, with minimal setup and no script-registration boilerplate.
• Compiler-Managed Workflow: let Perro sync scripts, generate glue code, and prepare supported assets so project setup stays small.
• Split Model: scripts are just Rust files (lifecycle + methods); they store #[State] structs which each instance gets a copy of.
• Safe Mutation: access through NodeID closures and engine-managed storage avoids borrow-contention edge cases in normal gameplay code (no "try_get_mut" fails).
• Fast Access: flat ID lookups keep common node/script operations efficient, with room to cache IDs for hot paths.
• Quick Iteration: project scripts build and reload in usually less than 1 second after initial compilation.

For more details, see the full documentation: perroengine.com/docs.

Local reference:

• Docs Index
• WASM / Web Target
• ResPath
• project.toml
• Feature Matrix
• Performance + Flexibility Philosophy
• Perro CLI

Dev Checks

• cargo check --workspace --all-targets
• cargo test --workspace
• cargo clippy --workspace --all-targets -- -D warnings -F clippy::all

Major Features

• Behavior Scripts + Per-Node State: a script is function entry points (lifecycle hooks + methods), not a mutable behavior object. When a node binds that script, runtime uses that node’s ctx.id to run behavior and resolve that node’s own #[State] via with_state!/with_state_mut!.
• Object-Centric Scene Model: parent/child relationships, concrete node types, and traditional game-object structure stay front and center.
• Compiler-Backed Asset Flow: dev stays flexible with plain files, while build/export bakes supported assets into fast static lookup paths and packs the rest.
• Powerful UI System: UI is built as a real engine system with relative sizing, clamping, and layouts designed to scale from simple menus to larger game interfaces.
• Flat ID-Based Runtime Access: node and script data are addressed by NodeID, enabling constant-time lookups for common operations and efficient cross-system interaction.
• Predictable Failure Modes: most runtime misses come from real-world state changes (deleted node, missing tag/name match, unbound script), not from borrow contention between unrelated systems (no try_get_mut runtime errors).
• Powerful Query Layer: if you prefer query-style access, filter by type, base type, tag, name, and subtree to gather NodeIDs, then operate directly through script/node APIs. See Query System.

Contributions

Perro is, of course, open source, and contributions are always appreciated: issue reports, new features, system optimizations, and other improvements. Everyone is welcome to join the project.

Support Perro

Donations help fund full-time development, faster features, and better tooling. If you want to support the project:

• Support Directly
• Sponsor Perro

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License

Perro is licensed under the Apache 2.0 License. See LICENSE for details.

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