Unity Shader 纹理映射的实现

// 纹理映射的编写
Shader "TMoon/04-Texture" {
    Properties{
        _Color("Color",Color) = (1,1,1,1)
        _MainTex("Main Tex",2D) = "white"{}
    }

    SubShader{

        Pass{
        
            Tags {"LightMode" = "ForwardBase"}

            CGPROGRAM

            #include "Lighting.cginc"

            #pragma vertex vert
            #pragma fragment frag

            fixed4 _Color;
            sampler2D _MainTex;
            float4 _MainTex_ST; //命名必须根据_MainTex 这里自动匹配面板的Tiling和Offset

            // application to vertex
            // 由应用程序传递给顶点函数
            struct a2v {
                float4 vertex:POSITION;
                float3 normal:NORMAL;
                float4 texcoord:TEXCOORD0; // 模型的纹理坐标
            };

            // vertex to fragment
            // 由顶点函数传递给片元函数
            struct v2f {
                float4 svPos:SV_POSITION;
                float3 worldNormal:TEXCOORD0;
                float4 worldVertex:TEXCOORD1;
                float2 uv:TEXCOORD2;
            };

            v2f vert(a2v v) {
                v2f f;

                f.svPos = mul(UNITY_MATRIX_MVP, v.vertex);
                f.worldNormal = normalize(UnityObjectToWorldNormal(v.normal));
                // 将模型空间的顶点坐标变换到世界空间上
                f.worldVertex = mul(v.vertex, unity_WorldToObject);
                // 将纹理坐标赋值给v2f.uv并赋值面板贴图的旋转缩放
                f.uv = v.texcoord.xy * _MainTex_ST.xy + _MainTex_ST.zw;

                return f;
            }

            float4 frag(v2f f) : SV_Target{

                fixed3 lightDir = normalize(WorldSpaceLightDir(f.worldVertex));

                // tex2D 根据贴图获取模型纹理坐标身上对应的像素点颜色值
                fixed3 texColor = tex2D(_MainTex,f.uv.xy) * _Color.rgb;

                // 为漫反射混合上每个像素点的纹理颜色
                fixed3 diffuse = _LightColor0.rgb * texColor * max(dot(f.worldNormal, lightDir), 0);

                return fixed4(diffuse,1);
            }

            ENDCG
        }
    }

    Fallback "VertexLit"
}