Spring Physics – Documentation

1. Introduction

Spring Physics is a Blender add-on that helps you create and manage multi-bone chains using Damped Track constraints and adjustable physics-style parameters.

It is designed for secondary animation elements such as character tails, ears, tentacles, and other connected bone structures.

The add-on provides a dedicated interface where you can create chains, manage individual bones, apply presets, and adjust their settings.

2. Installation

1. Download the Spring Physics add-on .py file.

2. Open Blender.

3. Navigate to Edit → Preferences → Get Extensions or the add-on installation interface available in your Blender version.

4. Install the downloaded add-on file.

5. Enable Spring Physics.

6. Open the 3D Viewport and press N to open the sidebar.

7. Find the Spring Physics tab.

3. Preparing Your Armature

Before creating a chain:

1. Select your armature.

2. Enter Pose Mode.

3. Make sure your bones form a connected hierarchy.

4. Select the bones you want to include in the chain.

5. Make the starting bone the active bone.

Important:

• Main Bone is the starting bone and must be active.

• First Bone is the ending bone.

• The chain must contain at least three bones.

• The add-on follows the first child in the bone hierarchy when building the chain.

4. Creating a Bone Chain

1. Open the Modern Rig tab in the 3D Viewport sidebar.

2. Locate the Chain Physics & Collision panel.

3. Set the Default Influence value.

4. Select the Main Bone and First Bone as described above.

5. Click Create Damped Chain.

The add-on will create Damped Track constraints for the intermediate bones and add them to the chain list.

The starting and ending bones are treated as chain endpoints.

5. Chain Settings

Each bone in the chain has individual settings.

Influence

Controls the influence of the Damped Track constraint.

Head / Tail

Provides a stored head/tail setting in the interface. The current Damped Track implementation may not expose this property, depending on the Blender constraint API.

Track Axis

Determines the tracking direction used by the Damped Track constraint.

Available options:

• X

• Y

• Z

• -X

• -Y

• -Z

6. Physics Parameters

Bounciness

A configurable parameter included in the bone settings and presets.

Speed

Multiplies the bone's Influence value when updating the constraint.

Gravity

Applies a basic vertical location adjustment to the bone.

Stretch

Adjusts the bone's scale to create a stretching-style effect.

Squash

Adjusts the bone's scale to create a squash-style effect.

7. Physics Presets

Spring Physics includes several presets to help you quickly configure your chain.

To apply a preset, click its button in the Physics Presets section. The selected preset is applied to all bones in the current list.

8. Collision Object

Spring Physics provides a basic collision-object assignment option.

1. Select a mesh object using the Collision Object field.

2. Create your bone chain.

3. Adjust the chain settings.

4. Click Update Constraints & Physics.

The add-on uses a simplified distance-based calculation to adjust bone positions around the assigned object's center.

Note: This is a basic collision approximation, not a full mesh collision or physics simulation system.

9. Updating Settings

After changing the settings of individual bones or applying a preset, click:

UPDATE CONSTRAINTS & PHYSICS

This applies the available constraint and transform adjustments to the bones in the list.

10. Managing the Bone List

The chain editor displays all bones currently included in the chain.

• Select a bone to edit its individual settings.

• Use the Clear List button to remove all bones from the editor list.

• Create another chain using the chain creation workflow.

11. Requirements

• Blender 5.0 or later.

• An armature with a connected bone hierarchy.

• Basic knowledge of Blender Pose Mode and armature selection.