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3d-games skill

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This skill helps you apply core 3D game development principles to rendering, shaders, physics, and cameras for faster, higher quality prototypes.

npx playbooks add skill vudovn/antigravity-kit --skill 3d-games

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SKILL.md

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---
name: 3d-games
description: 3D game development principles. Rendering, shaders, physics, cameras.
allowed-tools: Read, Write, Edit, Glob, Grep
---

# 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 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 |

---

## 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.

Overview

This skill covers core 3D game development principles for rendering, shaders, physics, cameras, lighting, and LOD. It focuses on practical techniques to achieve good performance and visual quality in real-time engines. Use it to inform design decisions, optimize pipelines, and avoid common anti-patterns.

How this skill works

The skill breaks down the rendering pipeline into vertex processing, rasterization, fragment processing, and final output, and explains common optimizations like frustum and occlusion culling, LOD, and batching. It outlines shader roles (vertex, fragment, compute), collider choices and physics heuristics, camera types and behaviors, lighting strategies, and when to bake versus render in real time.

When to use it

Designing or profiling a 3D rendering pipeline for performance
Deciding whether to write custom shaders for effects or optimization
Choosing collision shapes and physics approaches for gameplay entities
Implementing camera systems for player feel and collision avoidance
Planning lighting strategy and shadow performance for levels

Best practices

Prefer simple colliders for gameplay and reserve mesh colliders for static terrain
Use frustum/occlusion culling and batching to reduce draw calls
Implement multiple LODs and billboards for distant objects
Bake lighting and shadows where possible; use cascaded shadows for large worlds
Profile shaders and simplify expensive passes on constrained hardware

Example use cases

Create a third-person camera with smooth follow, look-ahead, and collision avoidance
Design LODs for an open-world scene to cut triangle count at distance
Replace mesh colliders with primitive shapes for physics-heavy scenes
Author a custom fragment shader for water and optimize with cheap variants on mobile
Bake static lighting for interior levels while keeping dynamic lights for players

FAQ

When should I write a custom shader?

Write custom shaders for unique visual effects, stylized rendering, or when built-in materials can't meet performance or aesthetic needs.

How do I balance visual fidelity and performance?

Prioritize perceived detail: use LOD, billboards, baked lighting, and culling. Profile hotspots and simplify expensive shaders or shadow usage on lower-end targets.