SKILL.md
3D Game Development
Principles for 3D game systems.
1. Rendering Pipeline
Stages
1. Vertex Processing → Transform geometry
2. Rasterization → Convert to pixels
3. Fragment Processing → Color pixels
4. Output → To screenOptimization Principles
| Technique | Purpose |
|---|---|
| Frustum culling | Don't render off-screen |
| Occlusion culling | Don't render hidden |
| LOD | Less detail at distance |
| Batching | Combine draw calls |
2. Shader Principles
Shader Types
| Type | Purpose |
|---|---|
| Vertex | Position, normals |
| Fragment/Pixel | Color, lighting |
| Compute | General computation |
When to Write Custom Shaders
- Special effects (water, fire, portals)
- Stylized rendering (toon, sketch)
- Performance optimization
- Unique visual identity
3. 3D Physics
Collision Shapes
| Shape | Use Case |
|---|---|
| Box | Buildings, crates |
| Sphere | Balls, quick checks |
| Capsule | Characters |
| Mesh | Terrain (expensive) |
Principles
- Simple colliders, complex visuals
- Layer-based filtering
- Raycasting for line-of-sight
4. Camera Systems
Camera Types
| Type | Use |
|---|---|
| Third-person | Action, adventure |
| First-person | Immersive, FPS |
| Isometric | Strategy, RPG |
| Orbital | Inspection, editors |
Camera Feel
- Smooth following (lerp)
- Collision avoidance
- Look-ahead for movement
- FOV changes for speed
5. Lighting
Light Types
| Type | Use |
|---|---|
| Directional | Sun, moon |
| Point | Lamps, torches |
| Spot | Flashlight, stage |
| Ambient | Base illumination |
Performance Consideration
- Real-time shadows are expensive
- Bake when possible
- Shadow cascades for large worlds
6. Level of Detail (LOD)
LOD Strategy
| Distance | Model |
|---|---|
| Near | Full detail |
| Medium | 50% triangles |
| Far | 25% or billboard |
7. Anti-Patterns
| ❌ Don't | ✅ Do |
|---|---|
| Mesh colliders everywhere | Simple shapes |
| Real-time shadows on mobile | Baked or blob shadows |
| One LOD for all distances | Distance-based LOD |
| Unoptimized shaders | Profile and simplify |
Remember: 3D is about illusion. Create the impression of detail, not the detail itself.