niaka3dayo/agent-skills-vrc-udon/unity-vrc-world-sdk-3

VRChat World SDK 3 Guide

Table of Contents

Method Migration

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

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.

Common Mistakes (NEVER List)

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

Reference Loading Guide

Load only what the task requires. When a request spans several rows, load every MANDATORY READ those rows list; a Do NOT Load entry never overrides another matching row's MANDATORY READ.

Before Starting a New World — Design Decisions

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

Design Philosophy: Quest First

If the world must run on Android, decide those constraints before tuning the PC build. Test each target separately.

Android headsets have mobile CPU, GPU, memory, and thermal budgets that differ from PC and vary by device:

• GPU: Realtime lights, shadows, overdraw, and complex shaders can dominate frame time
• Memory: Textures and lightmaps share limited system memory with the client
• Thermals: Sustained load can reduce available performance during a session

Measure each target device independently; PC results do not establish Android performance, and a single-client Quest result does not predict a particular PC frame rate. Use the Unity Profiler and the official Android content optimization guide 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: World shaders are unrestricted; prefer mobile-compatible shaders and profile custom ones
  ├── Lighting: Baked by default; retain realtime effects only after target-device profiling
  ├── Geometry: Budget approximately 250,000 triangles for the whole world; reduce further when profiling calls for it
  ├── Materials: Minimize unique materials and draw calls; no fixed world upload limit is documented
  ├── Audio: Mono, compressed, limited concurrent sources
  └── Physics: Simplified colliders, minimal Rigidbodies

SDK Versions

Active support / last verified: SDK 3.10.6

From v4.0.0 onward, the policy is latest stable SDK only; support moves to a new stable release only after this repository verifies it. A new stable release is not supported automatically. Current last verified target: 3.10.6.

The table below keeps feature-introduction history for migration reference. SDK 3.7.1-3.10.5 entries are historical information only; they are not active support or validation targets for this Skill. This is the Skill's support boundary, not a statement about VRChat's own SDK policy. Primary generated examples target SDK 3.10.6 unless a reference explicitly marks a historical migration case.