agent-skills-hub/3d-games

3D Game Development

Principles for 3D game systems.

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1. Rendering Pipeline

Stages

1. Vertex Processing → Transform geometry
2. Rasterization → Convert to pixels
3. Fragment Processing → Color pixels
4. Output → To screen

Optimization 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 |

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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

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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

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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

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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

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6. Level of Detail (LOD)

LOD Strategy

| Distance | Model | |----------|-------| | Near | Full detail | | Medium | 50% triangles | | Far | 25% or billboard |

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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 |

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Remember: 3D is about illusion. Create the impression of detail, not the detail itself.