shader-techniques

What this skill does

# Shader Techniques

## Shader Pipeline Overview

```
┌─────────────────────────────────────────────────────────────┐
│                    RENDERING PIPELINE                        │
├─────────────────────────────────────────────────────────────┤
│  CPU (Game Logic)                                            │
│       ↓                                                      │
│  VERTEX SHADER                                               │
│  ├─ Transform vertices to clip space                        │
│  ├─ Calculate normals, tangents                             │
│  └─ Pass data to fragment shader                            │
│       ↓                                                      │
│  RASTERIZATION (Fixed function)                              │
│  ├─ Triangle setup                                          │
│  ├─ Pixel coverage                                          │
│  └─ Interpolation                                           │
│       ↓                                                      │
│  FRAGMENT/PIXEL SHADER                                       │
│  ├─ Sample textures                                         │
│  ├─ Calculate lighting                                      │
│  └─ Output final color                                      │
│       ↓                                                      │
│  OUTPUT (Framebuffer)                                        │
└─────────────────────────────────────────────────────────────┘
```

## Basic Shader Structure

```hlsl
// ✅ Production-Ready: Basic Surface Shader (Unity HLSL)
Shader "Custom/BasicSurface"
{
    Properties
    {
        _MainTex ("Albedo", 2D) = "white" {}
        _Color ("Color Tint", Color) = (1,1,1,1)
        _Metallic ("Metallic", Range(0,1)) = 0.0
        _Smoothness ("Smoothness", Range(0,1)) = 0.5
        _NormalMap ("Normal Map", 2D) = "bump" {}
        _NormalStrength ("Normal Strength", Range(0,2)) = 1.0
    }

    SubShader
    {
        Tags { "RenderType"="Opaque" "Queue"="Geometry" }
        LOD 200

        CGPROGRAM
        #pragma surface surf Standard fullforwardshadows
        #pragma target 3.0

        sampler2D _MainTex;
        sampler2D _NormalMap;
        half4 _Color;
        half _Metallic;
        half _Smoothness;
        half _NormalStrength;

        struct Input
        {
            float2 uv_MainTex;
            float2 uv_NormalMap;
        };

        void surf(Input IN, inout SurfaceOutputStandard o)
        {
            // Albedo
            half4 c = tex2D(_MainTex, IN.uv_MainTex) * _Color;
            o.Albedo = c.rgb;

            // Normal mapping
            half3 normal = UnpackNormal(tex2D(_NormalMap, IN.uv_NormalMap));
            normal.xy *= _NormalStrength;
            o.Normal = normalize(normal);

            // PBR properties
            o.Metallic = _Metallic;
            o.Smoothness = _Smoothness;
            o.Alpha = c.a;
        }
        ENDCG
    }
    FallBack "Diffuse"
}
```

## Advanced Effects

### Toon/Cel Shading

```hlsl
// ✅ Production-Ready: Toon Shader
Shader "Custom/Toon"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _Color ("Color", Color) = (1,1,1,1)
        _RampTex ("Ramp Texture", 2D) = "white" {}
        _OutlineColor ("Outline Color", Color) = (0,0,0,1)
        _OutlineWidth ("Outline Width", Range(0, 0.1)) = 0.02
    }

    SubShader
    {
        Tags { "RenderType"="Opaque" }

        // Outline Pass
        Pass
        {
            Cull Front

            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            struct appdata
            {
                float4 vertex : POSITION;
                float3 normal : NORMAL;
            };

            struct v2f
            {
                float4 pos : SV_POSITION;
            };

            float _OutlineWidth;
            float4 _OutlineColor;

            v2f vert(appdata v)
            {
                v2f o;
                // Expand vertices along normals
                float3 scaled = v.vertex.xyz + v.normal * _OutlineWidth;
                o.pos = UnityObjectToClipPos(float4(scaled, 1.0));
                return o;
            }

            half4 frag(v2f i) : SV_Target
            {
                return _OutlineColor;
            }
            ENDCG
        }

        // Main Toon Pass
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            sampler2D _MainTex;
            sampler2D _RampTex;
            float4 _Color;

            struct appdata
            {
                float4 vertex : POSITION;
                float3 normal : NORMAL;
                float2 uv : TEXCOORD0;
            };

            struct v2f
            {
                float4 pos : SV_POSITION;
                float2 uv : TEXCOORD0;
                float3 worldNormal : TEXCOORD1;
            };

            v2f vert(appdata v)
            {
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                o.worldNormal = UnityObjectToWorldNormal(v.normal);
                return o;
            }

            half4 frag(v2f i) : SV_Target
            {
                // Sample albedo
                half4 col = tex2D(_MainTex, i.uv) * _Color;

                // Calculate diffuse with ramp
                float3 lightDir = normalize(_WorldSpaceLightPos0.xyz);
                float NdotL = dot(i.worldNormal, lightDir) * 0.5 + 0.5;
                float3 ramp = tex2D(_RampTex, float2(NdotL, 0.5)).rgb;

                col.rgb *= ramp;
                return col;
            }
            ENDCG
        }
    }
}
```

### Dissolve Effect

```hlsl
// ✅ Production-Ready: Dissolve Shader
Shader "Custom/Dissolve"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _NoiseTex ("Noise Texture", 2D) = "white" {}
        _DissolveAmount ("Dissolve Amount", Range(0, 1)) = 0
        _EdgeColor ("Edge Color", Color) = (1, 0.5, 0, 1)
        _EdgeWidth ("Edge Width", Range(0, 0.2)) = 0.05
    }

    SubShader
    {
        Tags { "RenderType"="Opaque" }

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            sampler2D _MainTex;
            sampler2D _NoiseTex;
            float _DissolveAmount;
            float4 _EdgeColor;
            float _EdgeWidth;

            struct v2f
            {
                float4 pos : SV_POSITION;
                float2 uv : TEXCOORD0;
            };

            v2f vert(appdata_base v)
            {
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                o.uv = v.texcoord;
                return o;
            }

            half4 frag(v2f i) : SV_Target
            {
                half4 col = tex2D(_MainTex, i.uv);
                float noise = tex2D(_NoiseTex, i.uv).r;

                // Discard dissolved pixels
                clip(noise - _DissolveAmount);

                // Add edge glow
                float edge = 1 - smoothstep(0, _EdgeWidth, noise - _DissolveAmount);
                col.rgb = lerp(col.rgb, _EdgeColor.rgb, edge);

                return col;
            }
            ENDCG
        }
    }
}
```

## Post-Processing Effects

```hlsl
// ✅ Production-Ready: Screen-Space Vignette
Shader "PostProcess/Vignette"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _Intensity ("Intensity", Range(0, 1)) = 0.5
        _Smoothness ("Smoothness", Range(0.01, 1)) = 0.5
    }

    SubShader
    {
        Pass
        {
            CGPROGRAM
            #pragma vertex vert_img
            #pragma fragment frag

            sampler2D _MainTex;
            float _Intensity;
            float _Smoothness;

            half4 frag(v2f_img i) : SV_Target
            {
                half4 col = tex2D(_MainTex, i.uv);

                // Calculate vignette
                float