GameSweetGame

Fix Character Movement Stutter in Unity

Fri, 20 Feb 2026 12:31:00 +0900

Check if Min Move Distance is set to 0 in your Character Controller.

I spent a long time tweaking movement code trying to figure out why the character was stuttering. Turns out, setting Min Move Distance to 0 fixed it right away.

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.

Unity Editor Crash Fix: D3D11 Swapchain Device Reset/Removed

Wed, 28 Jan 2026 00:00:00 +0900

I was working in Unity when suddenly the editor crashed with a D3D11 swapchain error — “Failed to present D3D11 swapchain due to device reset/removed.”

After reopening, it would crash within 3 seconds every time.

I tried everything — reinstalling Unity, changing versions — nothing worked.

I initially suspected Wallpaper Engine conflicting with DirectX in the background, but that wasn’t it either.

The key symptom was that the editor was sluggish and unresponsive, but the scene and game view rendered fine before crashing. This suggested it wasn’t a rendering issue but something loading in the background.

Then I noticed Windows Defender.

The fix: Allow the Unity Editor and Unity Package Manager through Windows Defender Firewall.

My theory: Unity tries to communicate with Package Manager and other services on startup. The firewall blocks these requests, stalling the main thread, causing GPU timing to slip, and eventually triggering the D3D11 device reset.

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.

Visualize Character Field of View with Unity Gizmos

Thu, 13 Mar 2025 00:00:00 +0900

Unity has built-in Gizmo functions that get called automatically.

OnDrawGizmos()

Always visible in the Scene view.

OnDrawGizmosSelected()

Only visible when the object is selected in the Scene view.

Great for visualizing field of view, attack range, and other debug shapes.

Unity Sword Trail Effect

Fri, 21 Feb 2025 00:00:00 +0900

I added basic attack animations to my character controller.

Swinging the sword felt empty. Games I’ve played always had that afterimage trail effect when swinging fast.

Implementation

Generate a mesh along the sword’s trajectory.

Draw a texture on the mesh and push it with a shader. The timing needs to follow right behind the sword’s path.

To sync the timing, adjust the shader texture Offset while watching the sword in the animation.

After searching for how animation stores shader texture values, I found Material._MainTex_ST.

Now I can control shader values through animation.

Tip: Set the shader texture mode to Clamp instead of Wrap. Otherwise the texture keeps repeating. With Clamp, it extends the last pixel seamlessly.

Basic sword trail effect done. Next step: make it 3D and add more options for fancier effects.

Extra Tip

When keying the animation, use the Broken tangent option to prevent the texture from visibly snapping back to the start when the attack animation ends.

Rendering a 3D Character — Transform Pipeline Order

Thu, 04 Jan 2024 00:00:00 +0900

Transform Order

Polygon × World Matrix × View Matrix × Projection Matrix

World Matrix — Place the model in world space (position, rotation, scale)
View Matrix — Transform relative to the camera
Projection Matrix — Project 3D onto 2D screen

DirectX Lighting Basics — Ambient, Diffuse, Specular

Wed, 03 Jan 2024 00:00:00 +0900

Lighting Calculation

float4 fvTotalAmbient = fvAmbient * fvBaseColor;
float4 fvTotalDiffuse = fvDiffuse * fNDotL * fvBaseColor;
float4 fvTotalSpecular = fvSpecular * pow( fRDotV, fSpecularPower );

return( saturate( fvTotalAmbient + fvTotalDiffuse + fvTotalSpecular ) );

Notes

saturate() clamps the value between 0 and 1
Do NOT use saturate in HDR (values above 1.0 are needed)
Large capacity is possible due to texture compression
Rim lighting technique: compute using the normal vector at the vertex stage

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.

DirectX UI System Implementation

Mon, 01 Jan 2024 00:00:00 +0900

When creating an entity, add UITestScript as a component. Pass the UI type during creation.

Each type is implemented inside the Update function.

UI Types

STATIC — A UI element that just sits there
ONMOUSE — A UI element that “breathes” when hovered
GAUGE — A gauge UI for time, hunger, mini-games, etc.
If animation is needed, more types can be added

Shader Code

float4 main(PixelIn input) : SV_TARGET
{
 float4 texColor = float4(1, 1, 1, 0);

 if(UItype == 1)
 {
 // Use frac() to wrap texture coordinates within 0-1 range
 // for seamless repetition
 input.tex.x = frac(input.tex.x);
 input.tex.y = frac(input.tex.y);
 texColor = shaderTexture.Sample(SampleType, input.tex);
 if (texColor.a < 0.01)
 discard;
 }
 else if(UItype == 2)
 {
 float2 textureOffset = float2(0.0f, 0.0f);
 float2 textureSize = float2(1.0f, 1 - textureTranslation);

 // Discard pixels outside the visible gauge area
 if (input.tex.x < textureOffset.x ||
 input.tex.x > textureOffset.x + textureSize.x ||
 1 - input.tex.y < textureOffset.y ||
 1 - input.tex.y > textureOffset.y + textureSize.y)
 {
 discard;
 }
 else
 {
 texColor = shaderTexture.Sample(SampleType, input.tex);
 }
 }
 else
 {
 texColor = shaderTexture.Sample(SampleType, input.tex);
 if (texColor.a < 0.01)
 discard;
 }
 return texColor;
}

Key Points

UItype == 1 (ONMOUSE): Uses frac() to wrap texture coordinates for a breathing animation effect
UItype == 2 (GAUGE): Controls the visible texture area via textureTranslation to create a fill effect
else (STATIC): Simple texture sampling with alpha discard below 0.01

Math Fundamentals for 2D Physics Engines

Mon, 01 Jan 2024 00:00:00 +0900

Drawing with D2D.

Linear algebra, calculus, Taylor series.

Key Physics Terms

Impulse: The product of force and the time it acts (force × time). Represents how much mass and velocity change.

Momentum: A physics term for the quantity of motion. Calculated by multiplying mass by velocity, measured in kg⋅m/s.

Damping: A force that resists motion, similar to friction.

Calculus

A concept devised by Isaac Newton.

Differentiation

Think of it as finding the slope at any arbitrary point on a function.

Power Rule

Quotient Rule

Product Rule

Chain Rule

Derivatives of Exponential and Logarithmic Functions

Integration

Finding the signed area under a curve.

Torque

Calculated using the cross product of vectors.

Eigenvalues

Needed for 3D physics engines (related to axes of rotation).

Python Star Pattern with While Loop

Sun, 28 Nov 2021 00:00:00 +0900

Instead of a simple star pattern, let’s take user input to decide how many rows to print.

☆
☆☆
☆☆☆
☆☆☆☆
☆☆☆☆☆

i = int(input("Enter the number of rows: "))
star = 1
while True:
 print("☆" * star)
 if star == i:
 break
 star += 1

input() returns a string by default. Convert it to int.
while True creates an infinite loop.
Each iteration prints stars and increments by 1. When it matches the input, break stops the loop.

Entering 7 prints stars from 1 to 7 rows.

Python: Search Lists and Strings with the "in" Operator

Wed, 24 Nov 2021 00:00:00 +0900

result1 = 1 in [1, 2, 3]
result2 = 5 in [1, 2, 3]

result3 = 1 not in [1, 2, 3]
result4 = 5 not in [1, 2, 3]

result5 = "j" in "python"
result6 = "y" in "python"
result7 = "y" not in "python"

print(result1) # True
print(result2) # False
print(result3) # False
print(result4) # True
print(result5) # False
print(result6) # True
print(result7) # False

result1: Is 1 in [1, 2, 3]? → Yes → True
result2: Is 5 in [1, 2, 3]? → No → False
not in is simply the opposite
Strings work just like lists
result5: Is “j” in “python”? → No → False