Animation on GameSweetGame

Adding Mixamo Control Rig in Blender

Thu, 19 Feb 2026 00:56:00 +0900

There’s a Mixamo Control Rig addon for Blender.

It makes editing animations super easy.

Make sure to attach the control rig while the model is in T-Pose to minimize errors.

Extract Animation Clips from FBX in Unity

Tue, 10 Feb 2026 11:29:00 +0900

Select the FBX file and press Ctrl+D to duplicate just the animation clip.

Make sure to finalize all settings before extracting.

Edit Game Animations with Blender and Mixamo Rig

Tue, 20 Jan 2026 12:00:00 +0900

I previously applied motion capture poses to a model, but they looked a bit awkward.

(Previous post: Applying Custom Animations to Your Game)

Let’s edit the animation in Blender.

After struggling with building bone controllers from scratch, I found something great — the Mixamo Rig addon.

With just one click, a control rig was generated. Easy.

Applying Custom Motion Capture Animations to Your Game

Tue, 20 Jan 2026 11:00:00 +0900

I want to make a polished action game. Let’s custom-make the attack animations.

I referenced this motion capture project on GitHub:

GitHub - 3D Motion Capture From Video

Using a Python pose estimation library, you can extract keypoint coordinates for head, shoulders, arms, legs, etc. These coordinates are then converted for use in Unity.

Overall Flow

External pose data (33 keypoints)
Convert to Unity coordinate system
Point objects (P0~P32)
Estimate rotation relative to bind direction
Root direction (yaw + slight tilt) estimation with smoothing

Normalizing File Values + Axis Correction

float px = float.Parse(toks[i * 3 + 0]) / scaleXY;
float py = float.Parse(toks[i * 3 + 1]) / scaleXY;
float pz = float.Parse(toks[i * 3 + 2]) / scaleZ;

Different XY/Z scales: Video-based pose estimation has much more noise in depth (Z)
invertZ: Corrects coordinate system difference between MediaPipe and Unity

Storing Bind Rotation

lUpperBind = lUpperArm.rotation;

Reference rotation from the T-Pose.

Automatic Bind Direction Estimation

lUpperBindDir = (lLowerArm.position - lUpperArm.position).normalized;

The core concept: which direction was this bone originally facing?

UpperArm → LowerArm direction = bone’s reference forward vector

A bit rough, but the motion came through. Now it’s time to refine it in Blender.

Assimp FBX Model Loading & Skinning Animation

Tue, 02 Jan 2024 00:00:00 +0900

Current status: Implementing in a simple project structure first, then porting to the team engine.

Version Issues

The bone count was way too high, so I tested by switching Assimp versions:

Latest version (v143)

v140

This is from checking a single mesh. The latest version reports 67 bones, while the older version correctly shows 2.

Skinning Animation — Head and Arms Stretching Bug

Skinning animation works, but the head and arms stretch out way too long.

~~After debugging for a while, I found that the bones in the FBX file were sticking out above the head.~~

I experimented in Blender and confirmed that when vertex positions are slightly above the bones on the Y axis, the arms and hands stretch. Since my animation causes stretching, the bones must be slightly offset downward.

Model Lying Down After Blender Export

Check the Y Up option in the export settings.

If the model is still lying down, try changing Y Up to something else, export, then switch back to Y Up and export again. That fixed it.