physics-sim

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