/physics-sim

name: physics-sim
description: Rigid body, soft body, and destruction setups in Blender including constraints, cell fracture debris, and baked caches via MCP.
license: MIT
metadata:
  author: https://github.com/arjun988
  version: "1.0.0"
  domain: blender
  role: specialist
  triggers: physics, rigid body, soft body, destruction, fracture, debris, constraint, simulation bake, collapse
  related-skills: vfx-fx, cloth-sim, animation, export-pipeline, collision-proxy

Physics Sim

Stable rigid/soft body setups. Motivated destruction. Baked caches.

When to Use

• Rigid body interactions and collapses
• Soft body jiggle / rubber / simple soft props
• Destruction and debris (cell fracture / pre-cut shards)
• Pre-vis physics before VFX polish

Workflow

Simplify collision meshes → Assign rigid/soft bodies
  → Constraints → Passive settings → Bake → Art-direct → Export cache

Rigid Body Quick Rules

| Role | Settings notes | |------|----------------| | Active | Moving debris / props | | Passive | Floors, walls, heavy anchors | | Convex hull | Fast, approximate | | Mesh | Accurate, heavier |

• Apply scale before sim
• Use margin appropriate to scale
• Collection: `COL_Physics_[Shot]`

Constraints

• Hinge / fixed / motor for mechanical links
• Breakable constraints for destruction beats
• Name: `RBCON_[Object]_[Type]`

Destruction Approach

1. Pre-cut shards (cell fracture or manual)
2. Island meshes as active rigid bodies
3. Passive shell until trigger frame
4. Animate trigger (force / keyframed activation)
5. Bake → cleanup interpenetrations

Soft Body

• Prefer for simple soft props; use `cloth-sim` for garments
• Goal weights to retain shape
• Soft + collision object required

Bake / Export

• Bake to cache before render
• Alembic/USD for cinematic debris
• For games: bake key poses or flipbook; rarely live Blender physics

Constraints

MUST DO

• Apply scale; use simplified colliders
• Bake before final delivery
• Trigger destruction intentionally (frame)

MUST NOT DO

• High-res sculpt meshes as active colliders
• Unbounded shard counts
• Leave sims unbaked for final renders

Reference Guide

| Topic | Reference | Load When | |-------|-----------|----------| | Rigid Body Presets | `references/rigid-body-presets.md` | When needed | | Destruction Pipeline | `references/destruction-pipeline.md` | When needed | | Sim Bake Checklist | `references/sim-bake-checklist.md` | When needed |