Unity Shaders and Rendering

Overview

Reference for Unity's rendering systems, shader development, lighting configuration, and visual effects. Covers all three render pipelines, Shader Graph, hand-written shaders, and VFX Graph.

Render Pipeline Comparison

Recommendation: Use URP for new projects unless targeting high-end visuals exclusively (HDRP). Built-in RP is legacy -- migrate when possible.

Shader Graph

Getting Started

1. Right-click in Project: Create > Shader Graph > URP > Lit Shader Graph
2. Double-click to open Shader Graph editor
3. Build node network connecting to Master Stack outputs
4. Create a Material using the shader, assign to renderers

Master Stack Outputs (URP Lit)

Common Node Patterns

Shader Graph Sub Graphs

Extract reusable node groups into Sub Graphs (Create > Shader Graph > Sub Graph). Use for shared noise functions, UV transformations, or custom lighting models.

Hand-Written Shaders (ShaderLab + HLSL)

URP Shader Structure

Shader "Custom/SimpleUnlit"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _Color ("Color", Color) = (1,1,1,1)
    }

    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;
            };

            TEXTURE2D(_MainTex);
            SAMPLER(sampler_MainTex);

            CBUFFER_START(UnityPerMaterial)
                float4 _MainTex_ST;
                half4 _Color;
            CBUFFER_END

            Varyings vert(Attributes IN)
            {
                Varyings OUT;
                OUT.positionHCS = TransformObjectToHClip(IN.positionOS.xyz);
                OUT.uv = TRANSFORM_TEX(IN.uv, _MainTex);
                return OUT;
            }

            half4 frag(Varyings IN) : SV_Target
            {
                half4 tex = SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, IN.uv);
                return tex * _Color;
            }
            ENDHLSL
        }
    }
}

Key differences from Built-in shaders:

• Use HLSLPROGRAM/ENDHLSL (not CGPROGRAM/ENDCG)
• Include URP shader library, not UnityCG.cginc
• Use TEXTURE2D/SAMPLER macros (not sampler2D)
• Wrap properties in CBUFFER_START(UnityPerMaterial) for SRP Batcher compatibility

Lighting

Light Types

Lighting Modes

Lightmap Baking Tips

• Set lightmap resolution based on scene scale (10-40 texels/unit for indoor)
• Use Light Probes for dynamic objects in baked scenes
• Use Reflection Probes for metallic/reflective surfaces
• Enable GPU Lightmapper for faster bake times
• Mark objects as Contribute GI in the Static flags

Post-Processing (Volume System)

Setup:
1. Add a Volume (Global or Local) to the scene
2. Create a Volume Profile asset
3. Add overrides: Bloom, Color Adjustments, Tonemapping, etc.
4. Camera must have Post Processing enabled (URP Camera settings)

VFX Graph vs Particle System

Use Particle System for gameplay-integrated effects (physics collisions, small counts). Use VFX Graph for visual spectacles (rain, fire, magic, ambient particles).

URP Render Features

Extend URP rendering with custom ScriptableRendererFeatures:

public class OutlineFeature : ScriptableRendererFeature
{
    OutlinePass _pass;

    public override void Create()
    {
        _pass = new OutlinePass();
        _pass.renderPassEvent = RenderPassEvent.AfterRenderingOpaques;
    }

    public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData data)
    {
        renderer.EnqueuePass(_pass);
    }
}

Common uses: custom outlines, screen-space effects, render texture generation, stencil-based effects.

Additional Resources

Reference Files

• references/shader-recipes.md -- Complete shader implementations: toon/cel shading, water, dissolve, hologram, force field, procedural skybox, stencil portal, vertex animation, custom lighting models
• references/lighting-vfx-detail.md -- Advanced lighting setups, GI troubleshooting, VFX Graph cookbook (fire, smoke, electricity, portals), Scriptable Render Pipeline customization, custom render passes