FireRat Pose Converter

Overview

FireRat Pose Converter is an enhanced Blender addon for copying poses between armatures and applying them as new rest poses. It is designed to handle differences in rest poses (e.g., T-pose to A-pose) and ensures that all associated meshes—including those with complex shape keys—are correctly updated to the new rest state.

This version is a fork of the original T2A Pose Converter, expanded with features like missing bone detection and improved compatibility.

Features

• Match Pose & Apply Rest: Copy a pose from a target armature and bake it as the new rest pose.
• Add Missing Bones: Automatically detects bones present in the target but missing in the source, and adds them with correct placement and parenting.
• Built-in Presets: Quick-access default Male and Female A-pose presets.
• Shape Key Preservation: Advanced logic to rebuild shape keys so they remain functional after the rest pose change.
• Smart Bone Matching: Automatically handles common prefix differences (e.g., matching mixamorig:Hips to Hips).
• Coexistence Mode: Designed to run alongside the original T2A plugin without naming conflicts.

Requirements

• Blender 3.6 or higher

Installation

1. Download the Pose_converter folder or zip.
2. In Blender, go to Edit → Preferences → Add-ons.
3. Click Install... and select the zip file, or manually place the folder in your Blender scripts directory.
4. Search for "FireRat Pose Converter" and enable it.

Usage

Main Conversion

The main workflow is located in the 3D View → Tool Shelf (N-panel) → FireRat tab.

1. Select Source Armature: Select the armature you want to modify in the 3D viewport.
2. Choose Target Source:
   • Custom: Select another armature already in your scene.
   • Default Male/Female: Use the included high-quality A-pose references.
3. Options:
   • Add Missing Bones: If enabled, the tool will create any bones found in the target that your source armature is currently missing before matching the pose.
4. Execute: Click Match Pose & Apply Rest.

Utilities

• Add Missing Bones: A standalone button to only add missing bones from the target without changing the current pose.
• Apply Current Pose as Rest: If you've manually posed your character and want to bake that state as the new rest pose (including mesh/shape key updates), use this utility.

Bone Matching Logic

The addon compares bones by stripping namespace prefixes. For example, prefix:BoneName will match BoneName or other_prefix:BoneName. This makes it highly compatible with Mixamo, VRM, and standard game engine rigs.

Shape Key Processing

Changing a rest pose usually breaks shape keys. This addon solves that by:

1. Creating a temporary snapshot of the mesh deformation.
2. Applying the new armature rest pose.
3. Re-calculating every shape key's vertex offsets relative to the new basis.
4. Cleaning up temporary data to leave a clean, functional model.

Credits & License

• Original Concept: T2A Pose Converter by CatHut.
• Enhancements: Developed by FireRat.
• License: MIT License.

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Note: Always backup your .blend file before performing rest pose operations, as these changes involve complex mesh data rebuilding.