UnityShaderBook/Assets/Shaders/Extra/Bump/MineBumpTestShader2.shader

Shader "Unlit/MineBumpTestShader2"
{
	Properties {
        _BumpMap("Normal Map", 2D) = "bump" {}
    }
    SubShader
    {
        Pass
        {
            Tags{"LightMode"="ForwardBase"}
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "Lighting.cginc"
            #include "UnityCG.cginc"

            sampler2D _BumpMap;

            struct a2v{
                float4 vertex : POSITION;
                float3 normal : NORMAL;
                float4 tangent : TANGENT;
                float2 uv : TEXCOORD0;
            };

            struct v2f {
                float3 worldPos : TEXCOORD0;
                float2 uv : TEXCOORD1;
                float4 pos : SV_POSITION;
                half3 wNormal : TEXCOORD2;
                half3 wTangent : TEXCOORD3;
                half3 wBitangent : TEXCOORD4;
            };

            // vertex shader now also needs a per-vertex tangent vector.
            // 顶点着色器现在也需要一个逐顶点的切线向量。
            // in Unity tangents are 4D vectors, with the .w component used to
            // 在Unity中，切线是一个四维的向量，w分向量用于
            // indicate direction of the bitangent vector.
            // 表现二次切线向量的方向
            // we also need the texture coordinate.
            // 我们仍然需要贴图来配合
            v2f vert (a2v v)
            {
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;
                o.uv = v.uv;
                o.wTangent = UnityObjectToWorldDir(v.tangent.xyz);
                o.wNormal = UnityObjectToWorldNormal(v.normal);
                // compute bitangent from cross product of normal and tangent
                // 通过计算法线与切线的叉积，得到二次切线bitangent,叉积*切线方向
                // half tangentSign = v.tangent.w * unity_WorldTransformParams.w;
                // output the tangent space matrix
                half tangentSign = v.tangent.w;
                o.wBitangent = cross(o.wNormal, o.wTangent) * tangentSign;
                
                return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {
                half3 tnormal = UnpackNormal(tex2D(_BumpMap, i.uv));
                // transform normal from tangent to world space
                // 将法线方向从切线空间转换到世界空间中。
                float3x3 TBNMatrix = float3x3(i.wTangent,i.wBitangent,i.wNormal);
                half3 worldNormal = mul(tnormal,TBNMatrix);
                half3 worldLightDir = normalize(_WorldSpaceLightPos0.xyz);
                fixed3 ambient = ShadeSH9(fixed4(worldNormal,1));
				fixed3 diffuse = _LightColor0.rgb * saturate(dot(worldNormal, worldLightDir));
                fixed4 c = fixed4(ambient+diffuse,1);
                return c;
                //return fixed4(tnormal,1);
            }
            ENDCG
        }
    }
}