chameleon/Assets/Shaders/PoseIconToon.shader

// Minimal cel/toon shader with an inverted-hull outline for the Pose Icon stage
// (icon screenshots of the staged Paintman). Deliberately NOT a URP/Lit clone:
// the stage is a controlled studio setup, so main-light cel banding + ambient is
// all the lighting it needs. Outline runs as a second pass (SRPDefaultUnlit, so
// URP renders it without a Render Feature); width is screen-space (pixel-ish)
// and distance-independent for consistent icon thickness.
Shader "Custom/PoseIconToon"
{
    Properties
    {
        [MainTexture] _BaseMap("Albedo", 2D) = "white" {}
        [MainColor] _BaseColor("Color", Color) = (1,1,1,1)

        [Header(Toon Shading)]
        _ShadeThreshold("Shade Threshold", Range(0.0, 1.0)) = 0.5
        _ShadeSoftness("Shade Softness", Range(0.001, 0.5)) = 0.05
        _ShadowTint("Shadow Tint", Color) = (0.55, 0.5, 0.65, 1)

        [Header(Outline)]
        _OutlineColor("Outline Color", Color) = (0.1, 0.08, 0.2, 1)
        _OutlineWidth("Outline Width (px at 1080p)", Range(0.0, 20.0)) = 6.0
    }

    SubShader
    {
        Tags { "RenderType" = "Opaque" "RenderPipeline" = "UniversalPipeline" "Queue" = "Geometry" }

        HLSLINCLUDE
        #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"

        CBUFFER_START(UnityPerMaterial)
            float4 _BaseMap_ST;
            half4 _BaseColor;
            half _ShadeThreshold;
            half _ShadeSoftness;
            half4 _ShadowTint;
            half4 _OutlineColor;
            half _OutlineWidth;
        CBUFFER_END
        ENDHLSL

        Pass
        {
            Name "ToonForward"
            // UniversalForwardOnly (not UniversalForward): drawn by BOTH the Forward and the
            // Deferred renderer (the deferred path only picks up ForwardOnly/SRPDefaultUnlit
            // passes for materials without a GBuffer pass - plain UniversalForward is skipped).
            Tags { "LightMode" = "UniversalForwardOnly" }

            HLSLPROGRAM
            #pragma vertex ToonVertex
            #pragma fragment ToonFragment

            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Lighting.hlsl"

            TEXTURE2D(_BaseMap);
            SAMPLER(sampler_BaseMap);

            struct Attributes
            {
                float4 positionOS : POSITION;
                float3 normalOS   : NORMAL;
                float2 uv         : TEXCOORD0;
            };

            struct Varyings
            {
                float4 positionCS : SV_POSITION;
                float2 uv         : TEXCOORD0;
                float3 normalWS   : TEXCOORD1;
            };

            Varyings ToonVertex(Attributes input)
            {
                Varyings output;
                output.positionCS = TransformObjectToHClip(input.positionOS.xyz);
                output.normalWS = TransformObjectToWorldNormal(input.normalOS);
                output.uv = TRANSFORM_TEX(input.uv, _BaseMap);
                return output;
            }

            half4 ToonFragment(Varyings input) : SV_Target
            {
                half4 albedo = SAMPLE_TEXTURE2D(_BaseMap, sampler_BaseMap, input.uv) * _BaseColor;

                Light mainLight = GetMainLight();
                half ndl = dot(normalize(input.normalWS), mainLight.direction) * 0.5h + 0.5h;
                half lit = smoothstep(_ShadeThreshold - _ShadeSoftness, _ShadeThreshold + _ShadeSoftness, ndl);

                half3 litColor = albedo.rgb * mainLight.color;
                half3 shadeColor = albedo.rgb * _ShadowTint.rgb;
                half3 ambient = albedo.rgb * SampleSH(input.normalWS) * 0.25h;

                return half4(lerp(shadeColor, litColor, lit) + ambient, albedo.a);
            }
            ENDHLSL
        }

        Pass
        {
            Name "Outline"
            Tags { "LightMode" = "SRPDefaultUnlit" }
            Cull Front

            HLSLPROGRAM
            #pragma vertex OutlineVertex
            #pragma fragment OutlineFragment

            struct Attributes
            {
                float4 positionOS : POSITION;
                float3 normalOS   : NORMAL;
            };

            struct Varyings
            {
                float4 positionCS : SV_POSITION;
            };

            Varyings OutlineVertex(Attributes input)
            {
                Varyings output;
                output.positionCS = TransformObjectToHClip(input.positionOS.xyz);

                // Extrude in clip space: constant on-screen width regardless of distance.
                float3 normalWS = TransformObjectToWorldNormal(input.normalOS);
                float3 normalCS = normalize(mul((float3x3)UNITY_MATRIX_VP, normalWS).xyz);
                float2 offset = normalCS.xy * _OutlineWidth * 2.0 / 1080.0 * output.positionCS.w;
                offset.x *= _ScreenParams.y / _ScreenParams.x; // keep width uniform on non-square aspect
                output.positionCS.xy += offset;
                return output;
            }

            half4 OutlineFragment(Varyings input) : SV_Target
            {
                return _OutlineColor;
            }
            ENDHLSL
        }
    }
}