VRChat Optimization & Integration Guide (v3.5)

VRChat is a primary target for HoloScript environments. The v3.4 compiler target emits raw UdonSharp (U#) C# code, providing direct access to the VRChat SDK 3.x API. This guide covers how to optimize your scripts for the Udon VM and handle networked synchronization.

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🏗️ Udon VM Mapping

HoloScript traits are mapped to specialized UdonSharp behaviors and VRC SDK components.

HoloScript Trait	VRC Component / U# Behavior
@grabbable	VRC_Pickup component + OnPickup / OnDrop
@throwable	Rigidbody + velocity calculation on OnDrop
@networked	[UdonSynced] variables with RequestSerialization()
@portal	VRC_PortalMarker with destination mapping
@spatial_audio	VRC_SpatialAudioSource

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📡 Networking & Synchronization

HoloScript's @networked attribute is highly efficient in VRChat, utilizing Udon's serialization system.

Synced Variables

Variables marked with @networked are compiled to [UdonSynced] members.

// HoloScript
object ScoreDisplay @networked {
    var score: number = 0
}

// Resulting UdonSharp (simplified)
[UdonSynced] private float score;

Manual vs Continuous Sync

By default, HoloScript uses Manual Synchronization for better performance. It calls RequestSerialization() only when a variable changes. To force continuous sync for high-frequency updates (e.g., real-time movement):

object MovingPlatform @networked(sync: "continuous") {
    // ...
}

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⚡ Performance Optimization

The "Udon Update" Cost

The Udon VM has overhead for every behavior with an Update() loop. HoloScript optimizes this by:

1. Consolidating Updates: Merging multiple script updates into a single HoloManager behavior.
2. Event-Driven Interactions: Preferring OnVRCPickup and OnPlayerTrigger over polling in Update.

Memory Management

Udon has strict memory limits. Avoid creating many small objects dynamically. Instead, use HoloScript's composition blocks to define your scene statically at load time.

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🛡️ Security & Anti-Cheat

• Owner-Only Logic: Crucial interactions are protected by checking Networking.IsOwner(gameObject).
• Validation: HoloScript's ConstitutionalValidator (if enabled) runs locally on each client to prevent malicious script state from being processed.

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🚀 Pro Tips

• VRC_ObjectSync: For purely physical objects, HoloScript automatically adds VRC_ObjectSync to handle physics reproduction across the network.
• Layers: Map your geometry to VRChat-specific layers (e.g., Walkable, MirrorReflection) for correct visual behavior.