UniVRM/Assets/VRM10/Runtime/TextureConvert/Resources/Shaders/MetallicRoughnessUnityToGltf.shader

Shader "UniVRM/MetallicRoughnessUnityToGltf"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}
		_Smoothness("Smoothness", Float) = 1.0
	}
	SubShader
	{
		// No culling or depth
		Cull Off ZWrite Off ZTest Always

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			
			#include "UnityCG.cginc"

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

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

			v2f vert (appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.uv = v.uv;
				return o;
			}
			
			sampler2D _MainTex;
			float _Smoothness;

			float4 frag (v2f i) : SV_Target
			{
				float4 col = tex2D(_MainTex, i.uv);
				float pixelSmoothness = (col.a * _Smoothness);
				float pixelRoughnessFactorSqrt = (1.0f - pixelSmoothness);
				float pixelRoughnessFactor = pixelRoughnessFactorSqrt * pixelRoughnessFactorSqrt;
				return float4(0, clamp(pixelRoughnessFactor, 0, 1.0), col.r, 1);
			}
			ENDCG
		}
	}
}