unity-development

Unity development pattern library

Reference patterns for Unity 6 development. Use as lookup.

Architecture decision tree

Project type: 2D? 3D? Mixed?
  Pick Render Pipeline: URP (most), HDRP (high-end), Built-in (legacy maintenance only)

Entity count at peak: < 100? 100-1000? > 1000?
  < 100: MonoBehaviour everywhere
  100-1000: MonoBehaviour with pooling
  > 1000: Consider ECS/DOTS — does team have experience?

Multiplayer?
  No: skip
  Cooperative / co-op: Netcode for GameObjects (current Unity recommendation)
  Competitive < 16 players: Netcode for GameObjects or Mirror
  Competitive 16+ players: dedicated server architecture, possibly DOTS for sim

Platform mix:
  PC only: easiest, no compromise
  PC + mobile: bake compromises in early (texture sizes, shader complexity)
  Console: budget for cert (3+ months); platform-specific work isolated to per-platform modules
  WebGL: GC pauses are devastating; profile early

Render Pipeline migration recipes

Built-in → URP

1. Install URP via Package Manager
2. Create URP Asset (right-click → Create → Rendering → URP Asset)
3. Project Settings → Graphics → Scriptable Render Pipeline Settings: drag URP Asset
4. Window → Rendering → Render Pipeline Converter (Unity 6 has automated converter)
5. Migrate custom shaders to Shader Graph or rewrite as URP-compatible HLSL
6. Verify post-processing — old PostProcessing Stack v2 replaced by URP Volume system

Built-in → HDRP

Heavier lift. Materials rebuild, lighting re-bake, custom shaders rewritten. Allocate weeks for a small project, months for a large one.

Custom shader patterns

// URP unlit shader skeleton
Shader "Custom/MyUnlit"
{
    Properties { _MainTex ("Texture", 2D) = "white" {} }
    SubShader
    {
        Tags { "RenderType"="Opaque" "RenderPipeline"="UniversalPipeline" }
        Pass
        {
            HLSLPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
            struct Attributes { float4 positionOS : POSITION; float2 uv : TEXCOORD0; };
            struct Varyings { float4 positionHCS : SV_POSITION; float2 uv : TEXCOORD0; };
            Varyings vert(Attributes IN) {
                Varyings OUT;
                OUT.positionHCS = TransformObjectToHClip(IN.positionOS.xyz);
                OUT.uv = IN.uv;
                return OUT;
            }
            half4 frag(Varyings IN) : SV_Target { return tex2D(_MainTex, IN.uv); }
            ENDHLSL
        }
    }
}