🎨 Asset Creation Guide

Guide for creating and managing game assets in R-Type.

📋 Asset Types

R-Type uses the following asset types:

Sprites: PNG images for entities, backgrounds, UI
Audio: OGG Vorbis for music and sound effects
Fonts: TTF/OTF fonts for text rendering
Shaders: GLSL fragment shaders for effects
Configuration: TOML files for game data

🖼️ Sprite Assets

Requirements

Format: PNG with transparency (RGBA) Color Depth: 32-bit (8-bit per channel + alpha) Resolution: Power of 2 recommended for best performance

Sprite Sizes

Asset Type	Recommended Size	Notes
Player Ship	64x64	Centered in sprite
Small Enemy	32x32	Simple shapes
Medium Enemy	48x48 or 64x64	More detail
Large Enemy	96x96 or 128x128	Boss elements
Boss	256x256+	Can be larger
Projectile	8x8 to 16x16	Small, clean
Power-Up	32x32	Recognizable icon
Background	1920x1080+	Tileable
UI Elements	Varies	Match UI scale

Creating Sprites

Using Aseprite

# Create new sprite
aseprite -b --sheet enemy_scout.png --data enemy_scout.json

# Create animation
aseprite -b \
  --sheet-type rows \
  --frame-range 0,7 \
  --sheet explosion.png \
  --data explosion.json \
  explosion.aseprite

Using GIMP

Create New Image
- File → New
- Set size (e.g., 64x64)
- Fill: Transparency
Design Sprite
- Use layers for organization
- Keep centered for rotation
- Use consistent style
Export
- File → Export As
- Format: PNG
- Enable: Save Alpha Channel
- Compression: 9 (maximum)

Pixel Art Guidelines

✅ Good Practices:
- Consistent pixel size
- Limited color palette (16-32 colors)
- Clear silhouette
- Readable at game resolution
- Anti-aliasing for smooth edges (optional)

❌ Avoid:
- Mixed pixel sizes
- Too many colors
- Blurry/muddy details
- Asymmetric designs (for centered objects)

Sprite Sheets

For animated sprites:

sprite_sheet.png:
┌─────┬─────┬─────┬─────┐
│ F0  │ F1  │ F2  │ F3  │  Animation frames
└─────┴─────┴─────┴─────┘

Config (enemies.toml):
sprite = "enemy_animated.png"
frame_count = 4
frame_width = 64
frame_height = 64
frame_duration = 0.1  # seconds per frame

Transparency

// Ensure proper alpha blending
// Sprites should have:
// - Fully transparent (alpha = 0) for background
// - Fully opaque (alpha = 255) for solid pixels
// - Semi-transparent (alpha = 128) for effects

🎵 Audio Assets

Music

Format: OGG Vorbis Sample Rate: 44.1 kHz Bitrate: 128-192 kbps Channels: Stereo Length: 2-4 minutes (loopable)

Creating Loop-able Music

Using Audacity:

Import/Create Track
Design Loop Point
- Fade in at start (0.5s)
- Fade out at end (0.5s)
- Ensure waveforms match at loop point
Export as OGG
- File → Export → Export as OGG
- Quality: 5-7
- Add metadata:
```
TITLE: Level 1 Theme
ARTIST: Composer Name
LOOP_START: 0
LOOP_END: 120.0
```

Music Categories

# Main menu (calm, atmospheric)
menu_music.ogg

# Level themes (energetic, driving)
level1_music.ogg
level2_music.ogg
level3_music.ogg

# Boss battles (intense, epic)
boss_music.ogg

# Victory/defeat (short, conclusive)
victory.ogg
defeat.ogg

Sound Effects

Format: OGG Vorbis Sample Rate: 44.1 kHz Bitrate: 96-128 kbps Length: < 2 seconds (typically)

Sound Effect List

Player:
- player_shoot.ogg (0.1s) - Laser shot
- player_hit.ogg (0.2s) - Taking damage
- player_death.ogg (0.5s) - Explosion
- player_powerup.ogg (0.3s) - Collecting power-up

Enemies:
- enemy_shoot.ogg (0.1s) - Enemy fire
- enemy_hit.ogg (0.1s) - Hitting enemy
- enemy_death_small.ogg (0.3s) - Small enemy dies
- enemy_death_large.ogg (0.5s) - Large enemy dies

Environment:
- explosion_small.ogg (0.5s)
- explosion_large.ogg (1.0s)
- warning.ogg (0.5s) - Boss warning
- level_complete.ogg (2.0s)

UI:
- ui_click.ogg (0.05s)
- ui_hover.ogg (0.05s)
- ui_select.ogg (0.1s)
- ui_error.ogg (0.2s)

Creating Sound Effects

Tools:

SFXR/BFXR: Generate retro game sounds
Audacity: Edit and process sounds
Freesound.org: Find free sound effects (check licenses)

Processing:

Record/generate sound
Normalize to -3 dB
Remove silence from start/end
Apply fade in/out (10ms)
Export as OGG (quality: 5)

🔤 Font Assets

Requirements

Format: TTF or OTF License: Ensure commercial use allowed Style: Readable at small sizes

Recommended Fonts

UI Text:
- Roboto (clean, modern)
- Open Sans (highly readable)
- Source Sans Pro (versatile)

Retro/Pixel Games:
- Press Start 2P
- VT323
- Pixellari

Score/Numbers:
- Orbitron (futuristic)
- Audiowide (tech-style)

Font Usage

# assets/config.toml
[fonts]
ui = "fonts/Roboto-Regular.ttf"
ui_bold = "fonts/Roboto-Bold.ttf"
score = "fonts/Orbitron-Bold.ttf"
dialogue = "fonts/OpenSans-Regular.ttf"

🌈 Shader Assets

Fragment Shaders

Format: GLSL (OpenGL Shading Language) Location: assets/shaders/

Example: Colorblind Mode

assets/shaders/colorblind.frag:

#version 330 core

uniform sampler2D texture;
uniform int mode; // 0=normal, 1=protanopia, 2=deuteranopia, 3=tritanopia

in vec2 TexCoords;
out vec4 FragColor;

void main() {
    vec4 color = texture2D(texture, TexCoords);
    
    if (mode == 1) { // Protanopia (red-blind)
        float r = 0.56667 * color.r + 0.43333 * color.g;
        float g = 0.55833 * color.r + 0.44167 * color.g;
        float b = color.b;
        FragColor = vec4(r, g, b, color.a);
    }
    else if (mode == 2) { // Deuteranopia (green-blind)
        float r = 0.625 * color.r + 0.375 * color.g;
        float g = 0.70 * color.r + 0.30 * color.g;
        float b = color.b;
        FragColor = vec4(r, g, b, color.a);
    }
    else if (mode == 3) { // Tritanopia (blue-blind)
        float r = color.r;
        float g = color.g;
        float b = 0.95 * color.r + 0.05 * color.g;
        FragColor = vec4(r, g, b, color.a);
    }
    else {
        FragColor = color;
    }
}

Example: Vignette Effect

assets/shaders/vignette.frag:

#version 330 core

uniform sampler2D texture;
uniform float radius;    // 0.0 - 1.0
uniform float softness;  // 0.0 - 1.0

in vec2 TexCoords;
out vec4 FragColor;

void main() {
    vec4 color = texture2D(texture, TexCoords);
    
    // Calculate distance from center
    vec2 center = vec2(0.5, 0.5);
    float dist = distance(TexCoords, center);
    
    // Calculate vignette
    float vignette = smoothstep(radius, radius - softness, dist);
    
    // Apply vignette
    FragColor = vec4(color.rgb * vignette, color.a);
}

📝 Configuration Assets

Enemy Definition

config/game/enemies.toml:

[[enemy]]
id = "scout"
name = "Scout Fighter"
health = 20
speed = 150.0
damage = 10
score = 100
sprite = "enemy_scout.png"        # Reference to sprite
behavior = "straight"
fire_rate = 2.0
projectile = "enemy_bullet"       # Reference to projectile
drop_chance = 0.1                 # 10% power-up drop

# Visual effects
death_effect = "explosion_small"
death_sound = "enemy_death_small.ogg"
spawn_sound = "enemy_spawn.ogg"

# Animation (if sprite sheet)
animated = true
frame_count = 4
frame_duration = 0.15

Level Definition

config/game/levels/level1.toml:

[level]
id = 1
name = "Asteroid Field"
background = "bg_space_1.png"
music = "level1_music.ogg"
duration = 180

# Parallax scrolling
[[level.parallax]]
sprite = "stars_far.png"
speed = 0.1
[[level.parallax]]
sprite = "asteroids_near.png"
speed = 0.8

# Enemy waves
[[wave]]
time = 10
enemy = "scout"
count = 8
formation = "v"
spawn_interval = 0.5
spawn_x = 1920
spawn_y = 360

# Boss
[[boss]]
enemy = "boss_serpent"
spawn_time = 180
music = "boss_music.ogg"
warning_time = 10

📂 Asset Organization

assets/
├── img/
│   ├── entities/
│   │   ├── players/
│   │   │   ├── player_ship.png
│   │   │   └── player_ship_boost.png
│   │   ├── enemies/
│   │   │   ├── enemy_scout.png
│   │   │   ├── enemy_interceptor.png
│   │   │   └── boss_serpent.png
│   │   ├── projectiles/
│   │   │   ├── bullet_player.png
│   │   │   ├── laser_beam.png
│   │   │   └── missile.png
│   │   └── powerups/
│   │       ├── powerup_red.png
│   │       ├── powerup_blue.png
│   │       └── powerup_shield.png
│   ├── backgrounds/
│   │   ├── bg_space_1.png
│   │   ├── bg_nebula.png
│   │   └── parallax/
│   ├── effects/
│   │   ├── explosion_small.png
│   │   ├── explosion_large.png
│   │   └── engine_trail.png
│   └── ui/
│       ├── button_normal.png
│       ├── button_hover.png
│       └── health_bar.png
├── audio/
│   ├── music/
│   │   ├── menu_music.ogg
│   │   ├── level1_music.ogg
│   │   └── boss_music.ogg
│   └── sfx/
│       ├── player/
│       ├── enemies/
│       └── ui/
├── fonts/
│   ├── Roboto-Regular.ttf
│   ├── Roboto-Bold.ttf
│   └── Orbitron-Bold.ttf
└── shaders/
    ├── colorblind.frag
    ├── vignette.frag
    └── scanlines.frag

🎨 Style Guidelines

Color Palette

Primary Colors:
- Player: Blue (#00BFFF)
- Enemies: Red (#FF4444)
- Power-ups: Yellow (#FFD700), Green (#00FF00)

Secondary Colors:
- UI: Dark Blue (#1A1A2E), Light Gray (#EAEAEA)
- Effects: White (#FFFFFF), Orange (#FFA500)

Background:
- Space: Dark Blue/Black (#0A0A1A)
- Nebula: Purple/Pink (#8844AA, #FF44AA)

Visual Consistency

✅ Consistent:
- Same art style across all assets
- Matching color palette
- Uniform outline thickness (pixel art)
- Similar level of detail

❌ Inconsistent:
- Mixing realistic and cartoonish styles
- Clashing color schemes
- Different pixel densities
- Varying quality levels

🔧 Asset Tools

Recommended Software

2D Graphics:

Aseprite - Pixel art animation
GIMP - Free image editor
Inkscape - Vector graphics
Krita - Digital painting

Audio:

Audacity - Audio editing
LMMS - Music production
BFXR - Sound effect generator
Bosca Ceoil - Simple music maker

Fonts:

FontForge - Font editor
Google Fonts - Free fonts
DaFont - Font repository

📏 Performance Considerations

Optimization Tips

Sprite Atlases: Combine multiple sprites into one texture
Compression: Use PNG compression (OptiPNG, PNGCrush)
Resolution: Don't exceed necessary size
Audio: Use appropriate bitrate (128kbps for music, 96kbps for SFX)
Lazy Loading: Load assets on-demand when possible

Asset Budget

Target Size:
- Total assets: < 500 MB
- Single sprite: < 1 MB
- Music track: < 5 MB
- Sound effect: < 100 KB
- Font: < 1 MB

🧪 Testing Assets

Asset Checklist

In-Game Testing

# Run game and check:
Asset loads without errors
Appears correctly on screen
Animates smoothly (if applicable)
Sounds play without popping/clipping
Music loops seamlessly
No performance impact

📚 Asset Attribution

If using third-party assets:

## Credits

### Graphics
- Player ship sprite by [Artist Name] (CC BY 4.0)
- Enemy sprites from [Source] (Public Domain)

### Audio
- Menu music by [Composer] (CC BY-SA 3.0)
- Sound effects from [Freesound.org] (CC0)

### Fonts
- Roboto by Google Fonts (Apache License 2.0)
- Orbitron by Matt McInerney (SIL Open Font License)

Happy creating! 🎨

📋 Asset Types​

🖼️ Sprite Assets​

Requirements​

Sprite Sizes​

Creating Sprites​

Using Aseprite​

Using GIMP​

Pixel Art Guidelines​

Sprite Sheets​

Transparency​

🎵 Audio Assets​

Music​

Creating Loop-able Music​

Music Categories​

Sound Effects​

Sound Effect List​

Creating Sound Effects​

🔤 Font Assets​

Requirements​

Recommended Fonts​

Font Usage​

🌈 Shader Assets​

Fragment Shaders​

Example: Colorblind Mode​

Example: Vignette Effect​

📝 Configuration Assets​

Enemy Definition​

Level Definition​

📂 Asset Organization​

🎨 Style Guidelines​

Color Palette​

Visual Consistency​

🔧 Asset Tools​

Recommended Software​

📏 Performance Considerations​

Optimization Tips​

Asset Budget​

🧪 Testing Assets​

Asset Checklist​

In-Game Testing​

📚 Asset Attribution​

📖 Related Documentation​

📋 Asset Types

🖼️ Sprite Assets

Requirements

Sprite Sizes

Creating Sprites

Using Aseprite

Using GIMP

Pixel Art Guidelines

Sprite Sheets

Transparency

🎵 Audio Assets

Music

Creating Loop-able Music

Music Categories

Sound Effects

Sound Effect List

Creating Sound Effects

🔤 Font Assets

Requirements

Recommended Fonts

Font Usage

🌈 Shader Assets

Fragment Shaders

Example: Colorblind Mode

Example: Vignette Effect

📝 Configuration Assets

Enemy Definition

Level Definition

📂 Asset Organization

🎨 Style Guidelines

Color Palette

Visual Consistency

🔧 Asset Tools

Recommended Software

📏 Performance Considerations

Optimization Tips

Asset Budget

🧪 Testing Assets

Asset Checklist

In-Game Testing

📚 Asset Attribution

📖 Related Documentation