/unity-vrc-world-sdk-3

name: unity-vrc-world-sdk-3
description: >
    VRChat World SDK 3 guide for scene and Inspector setup, component placement,
    optimization, and upload. Use for VRChat world scene configuration,
    VRC SDK components, layers, baked lighting, Quest/Android performance,
    Dynamics for Worlds, Build Panel warning triage, validation, and upload.
    Covers VRC_SceneDescriptor, VRC_Pickup, VRC_Station, VRC_Mirror,
    VRC_ObjectSync, VRC_CameraDolly, spawn points, collision matrices,
    PhysBone and Contact component placement, Box Contacts,
    Global Avatar PhysBone Colliders, and VRCPhysBoneCollider component setup.
    SDK 3.7.1-3.10.4. Triggers on: VRChat world scene, VRC SDK, scene setup,
    component placement, optimization, Quest support, light baking, upload,
    SDK validation, Build Panel warning, Auto Fix, red warning, yellow warning, or white warning.
    Do not use for UdonSharp C# or VRCTween calls; use
    unity-vrc-udon-sharp for runtime scripting.
license: MIT
metadata:
    author: niaka3dayo
    version: "3.0.1"
    tags: vrchat, world-sdk, scene-setup, optimization, components, upload, sdk-validation, build-panel

VRChat World SDK 3 Guide

Table of Contents

| Section | Content | Reference | | ------------------------------------------ | -------------------------- | ------------------------------- | | [Scene Setup](#scene-setup) | VRC_SceneDescriptor, Spawn | This file | | [Components](#components) | Pickup, Station, Mirror | `references/components.md` | | [Layers & Collision](#layers--collision) | Layers, Collision Matrix | `references/layers.md` | | [Performance](#performance) | Optimization guide | `references/performance.md` | | [Lighting](#lighting) | Lighting settings | `references/lighting.md` | | [Audio & Video](#audio--video) | Audio, Video players | `references/audio-video.md` | | [Build Validation](references/build-validation.md) | Red/yellow/white SDK alerts | `references/build-validation.md` | | [World Upload](#world-upload) | Upload workflow | `references/upload.md` | | [Troubleshooting](#troubleshooting) | Problem solving | `references/troubleshooting.md` | | [Cheatsheet](CHEATSHEET.md) | Quick reference | `CHEATSHEET.md` |

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Method Migration

The following public methods were renamed because an unprefixed, parameterless public UdonSharp method remains callable through legacy network dispatch:

| Before | After | |---|---| | `ForceDropPickup` | `_ForceDropPickup` | | `IsHeld` | `_IsHeld` | | `IsOccupied` | `_IsOccupied` | | `StopSound` | `_StopSound` | | `SlowUpdate` | `_SlowUpdate` |

Update Inspector event strings, `SendCustomEvent*` calls, delayed events and `nameof(...)` expressions, and cross-behaviour calls. Compatibility aliases are not provided because an old unprefixed alias would restore the same legacy network exposure.

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Common Mistakes (NEVER List)

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

| # | NEVER do this | Why it hurts | Use instead | |---|---------------|-------------|-------------| | 1 | Enable Mirror by default (active on world join) | A mirror adds another costly scene render; the impact depends on view, scene, resolution, and device | Default Mirror OFF; add a player-controlled toggle and profile each target device | | 2 | Use realtime directional lights with real-time shadows without profiling | Realtime shadow cost varies with scene geometry, view, and target device and can dominate frame time on Android | Prefer baked lightmaps + light probes; profile the target device before keeping any realtime shadows | | 3 | Set Respawn Height at or above the world floor | Player respawns → falls → respawns again → infinite loop; players cannot recover | Set to an unreachable depth (e.g., floor at Y=0 → Respawn at Y=-100) | | 4 | Skip "Setup Layers for VRChat" on a new project | Layer collision matrix is wrong by default — players walk through walls, Pickups clip floors | Run VRChat SDK > Builder > "Setup Layers for VRChat" before placing any colliders | | 5 | Enable Post-Processing without an Android build profile | Post-processing is disabled at runtime on Android, so the authored effect will not appear and unnecessary resources can still enlarge the build | Use a separate Android build profile with post-processing removed | | 6 | Place more than 2 active video players simultaneously | Each player adds significant decoding overhead; running >2 simultaneously is a common cause of frame drops and audio issues in practice | Disable extra players at scene start; activate only the currently playing one | | 7 | Use Cloth on Android, or add many Unity Constraints without profiling | Cloth is disabled on Android. Unity Constraints are permitted in worlds, but overuse can significantly affect performance | Remove Cloth from the Android build; prefer VRC Constraints for new work and profile any constraint-heavy setup | | 8 | Upload without completing a lightmap bake | Realtime GI adds substantial scene-dependent render cost and is unsuitable as an unmeasured fallback on Android | Bake lights before upload, then verify the result on the target device | | 9 | Place player walkable surfaces on Default layer (0) | Collision matrix is wrong by default — avatar physics collision is unreliable; players may clip through geometry | Use Environment (layer 11) for all walkable geometry, walls, and floors | | 10 | Use very high lightmap resolution for large areas without profiling | Texture memory can spike significantly at high resolutions; a common cause of OOM crashes on mobile headsets | Start at 10-20 texels/unit (PC) / 5-10 (Quest) as a practical guideline; profi