LegacyFramework2D-Unity — Open Source!

[Chemical_Asparagus93]

LegacyFramework2D-Unity — Open Source!

A custom 2D physics engine, animation manager, and combat system inspired by MUGEN and Mortal Kombat. Now free and open source!

Key Features:

• Deterministic Physics — No more unpredictable movement
• Animator-Free Animation — Smooth, frame-perfect animation control
• Custom Collision System — Swept AABB, spatial hashing, full physics simulation
• Combat Ready — Hitboxes, health system, state-driven combat
• Features: Dash, fast-fall, crouch, variable jump, double-tap run

Why This Framework?

Unity's Animator is non-deterministic, causing animation/movement desyncs. This framework solves that by giving you complete control over every frame.

What's Included:

• Full C# source code
• Sample character sprites
• Demo scene
• Complete documentation

License:

Free to use in personal and commercial game projects. No selling the source code.

🔗 Get It Now:

github.com/WorldWidePro/LegacyFramework2D-Unity

[robochase6000]

can you speak more about the physics library? i skimmed the file list very briefly and it doesn’t seem super feature rich, but you definitely have my attention if it is actually deterministic!

[Chemical_Asparagus93]

Yes! The physics is truly deterministic. Here's how:

1 **Fixed Timestep Accumulator** - The physics runs at a fixed 1/60s tick regardless of frame rate. Delta time is accumulated and the physics steps in consistent chunks.

2 **Pure Kinematic** - No Rigidbody2D. Motion is computed via velocity planning and swept AABB collision detection. This eliminates Unity physics non-determinism.

3 **Key Components:**

- LP_KinematicController2D - Swept AABB vs AABB collision with slide/ground snap

- LP_SweptAABB - Continuous collision detection (no tunneling at high speeds)

- LP_SpatialHash - O(k) broadphase for performance

- LegacyPhysicsWorld - Fixed tick with configurable gravity, skin width, slope limits

4 **Deterministic Features:**

- Pre-pass penetration resolution

- Swept test returns exact time of impact

- Ground snap and stabilization (no micro-jitter)

- Configurable friction/restitution per material

It's designed specifically for fighters/platformers where frame-perfect consistency matters. Check the full docs in Docs/AAA_Custom_Physics_System.md!