unity-vrc-world-sdk-3

name: unity-vrc-world-sdk-3 description: > VRChat World SDK 3 scene setup and optimization guide. Use this skill when configuring VRChat world scenes, placing SDK components, setting up layers, optimizing performance, or uploading worlds. Covers VRC_SceneDescriptor, spawn points, VRC_Pickup, VRC_Station, VRC_Mirror, VRC_ObjectSync, VRC_CameraDolly, layer/collision matrix, baked lighting, Quest/Android limits, Dynamics for Worlds, Build Panel validation alerts, and upload workflow. SDK 3.7.1 - 3.10.4 coverage. Triggers on: VRChat world, VRC SDK, scene setup, VRC_SceneDescriptor, spawn point, VRC_Pickup, VRC_Station, VRC_ObjectSync, layer setup, PhysBones, Contacts, Box Contacts, Global Avatar PhysBone Colliders, VRCPhysBoneCollider, VRCTween, optimization, Quest support, light baking, upload, SDK validation, Build Panel warning, Auto Fix, red warning, yellow warning, white warning, FPS improvement. Related: Use unity-vrc-udon-sharp for UdonSharp C# coding. license: MIT metadata: author: niaka3dayo version: "2.5.1" tags: vrchat, world-sdk, scene-setup, optimization, components, upload, sdk-validation, build-panel

VRChat World SDK 3 Guide

Table of Contents

Common Mistakes (NEVER List)

These cause silent world failures, performance disasters, or Quest incompatibility:

Reference Loading Guide

Load only what the task requires.

Before Starting a New World — Design Decisions

These decisions shape every downstream choice. Make them first, before placing any component.

Design Philosophy: Quest First

Build for Quest and get PC for free. Build for PC and Quest becomes a separate project.

Quest (Meta Quest 2/3/Pro) defines the performance budget:

• CPU/GPU: ~2× slower than PC VR; tile-based GPU with no hardware shadow maps
• VRAM: ~4 GB shared with OS (vs 6–12 GB on PC); no HDR framebuffer
• Thermal throttling: Sustained 100% GPU load causes clock reduction within minutes

If a world runs at 72 FPS on Quest with a single test client, it will typically run at 90+ FPS on PC — though results vary by shader complexity, CPU-bound workloads, and hardware differences. The converse rarely holds. Verify against the official VRChat optimization documentation before publishing.

NEVER optimize exclusively for PC with "Quest support added later" — by that point, lighting, materials, and mesh density are all locked to PC quality, and the Quest port requires rebuilding everything.

Quest First Cascade — when Quest is required, every downstream decision inherits constraints:

Quest required? → Yes
  ├── Shaders: Mobile-only (Standard Lite, Toon Lit)
  ├── Lighting: Fully baked (no realtime shadows)
  ├── Geometry: 50K-100K triangles (target range)
  ├── Materials: < 25 unique materials
  ├── Audio: Mono, compressed, limited concurrent sources
  └── Physics: Simplified colliders, minimal Rigidbodies

SDK Versions

Supported versions: SDK 3.7.1 - 3.10.4

Important: SDK versions below 3.9.0 are deprecated as of December 2, 2025. New world uploads are no longer possible with these versions.

Scene Setup

VRC_SceneDescriptor (Required)

Exactly one is required in every VRChat world.

[VRCWorld Prefab]
├── VRC_SceneDescriptor (Required)
├── VRC_PipelineManager (Auto-added)
├── VRCWorldSettings (Optional - movement speed settings)
└── AvatarScalingSettings (Optional - avatar scale limits)

All Properties

Reference Camera Usage

// Usage:
// 1. Adjust Near/Far clipping (recommended for VR: 0.01 ~ 1000)
// 2. Apply Post Processing effects
// 3. Set background color

// ⚠️ MUST disable the Camera component after configuring — an active Reference Camera
//    renders a second viewport. VRChat reads only the camera settings, not its output.
// Assign the configured (disabled) Camera to VRC_SceneDescriptor > Reference Camera.

Spawn Points Setup

// Spawn points are empty GameObjects assigned to VRC_SceneDescriptor > Spawns array.
// Players enter facing the Z+ direction of the spawn Transform.

// VRChat-specific requirements:
// - At least 2-3 spawn points (for simultaneous joins — single spawn causes overlap)
// - Place slightly above the floor (~0.1m) to avoid floor collision on spawn
// - Keep clear of obstacles (VR player guardian area is larger than their avatar)
// - Account for VR guardian boundaries — desktop player sizes differ from VR

Required Setup Checklist

□ Exactly one VRCWorld Prefab exists in the scene
□ At least one Transform set in Spawns
□ Respawn Height set to an appropriate value (well below the floor)
□ Reference Camera configured for clipping distances (for VR)
□ Layer/Collision Matrix correctly configured
□ "Setup Layers for VRChat" has been executed

Components

MANDATORY READ references/components.md (~800 lines) before configuring any VRC component below. Load in full — dependency requirements and Udon event hooks are distributed throughout. Do NOT Load: references/audio-video.md (unless the task involves audio/video components), references/lighting.md.

VRC_ObjectSync vs UdonSynced

SDK 3.8.0+: Force Kinematic On Remote — Makes Rigidbody kinematic on non-owner clients, preventing unexpected physics behavior.

Layers & Collision

VRChat Reserved Layers

Layer Setup Steps

1. VRChat SDK > Show Control Panel
2. Builder tab
3. Click "Setup Layers for VRChat"
4. Collision Matrix is automatically configured

MANDATORY READ references/layers.md when setting up collision or debugging physics. The default Unity collision matrix differs from the VRChat-correct one — always verify. Do NOT Load: references/audio-video.md, references/upload.md.

Performance

Target FPS

Critical Limits

Quest/Android Restrictions

Performance Optimization Workflow

MANDATORY READ: Load performance.md before optimizing — measure first, then target the largest bottleneck — and references/lighting.md for Quest optimization. Do NOT Load: references/audio-video.md, references/upload.md.

Lighting

Baked Lighting (Required)

✅ Recommended settings:
├── Lightmapper: Progressive GPU
├── Lightmap Resolution: 10-20 texels/unit (PC) / 5-10 (Quest)
├── Light Mode: Baked or Mixed
└── Light Probes: Place along player paths

❌ Avoid:
├── Realtime lights (dynamic shadows)
├── High-resolution lightmaps (memory consumption)
└── Excessive Reflection Probes

MANDATORY READ references/lighting.md when configuring lightmaps or light probe placement. Do NOT Load: references/audio-video.md, references/upload.md, references/layers.md.

Audio & Video

VRC_SpatialAudioSource

Plan each world AudioSource with a VRC_SpatialAudioSource: a bare AudioSource triggers a VRChat SDK Build Panel warning. Add the companion deliberately, avoid Auto Fix as a blind default, and do not overwrite existing VRC_SpatialAudioSource values or tuned AudioSource curves unless requested.

When preserving an existing AudioSource, keep volume, spatialBlend, rolloffMode, maxDistance, and custom curves; use Gain 0 dB; enable Use AudioSource Volume Curve for tuned 3D rolloff; match Far to the existing maxDistance or intended audible range; and keep Near at 0m unless an existing minDistance/Near value was intentionally authored.

Video Player Selection

MANDATORY READ references/audio-video.md for VRC_SpatialAudioSource or video player configuration. Optional: references/components.md when wiring audio/video components. Do NOT Load: references/lighting.md, references/performance.md.

World Upload

Upload Steps

1. Check Validation
   └── VRChat SDK > Build Panel > Validations

2. Build & Test (local testing)
   └── "Build & Test New Build"
   └── Supports multi-client testing

3. Upload
   └── "Build and Upload"
   └── Set Content Warnings
   └── Set Capacity

4. Publish settings
   └── Configure public/private on the VRChat website

Pre-Upload Checklist

□ VRC_SceneDescriptor × 1
□ Spawns configured
□ Respawn Height appropriate
□ Layer/Collision Matrix verified
□ Light baking complete
□ Mirror default OFF
□ 45+ FPS in VR
□ No Validation errors
□ Content Warnings set
□ Capacity set

MANDATORY READ references/upload.md before running Build & Upload. Verify all pre-upload checklist items first. MANDATORY READ references/build-validation.md when the user asks about SDK Build Panel validation, red/yellow/white warnings, Auto Fix, or a copied validation message. Do NOT Load: references/audio-video.md, references/lighting.md.

Troubleshooting

Quick Router

Identify the symptom category and jump to the reference section:

MANDATORY READ references/troubleshooting.md when diagnosing any issue. Do NOT Load for non-troubleshooting tasks.

Related Skills

For C# scripting, network sync, and UdonSharp event implementation, use the unity-vrc-udon-sharp skill.

Templates (assets/templates/)

Starter templates for common SDK component patterns. Each template compiles without modification; adjust Inspector fields and extend the event stubs for your world.

References