4.使用结构体简化Shader代码

无返回值（in,out）

Shader"Custom/Struct"
{
    Properties
    {
        //通过材质面板的颜色和纹理来修改fragment
        _MainColor("MainColor",Color) = (1,1,1,1)
        _MainTex("MainTex",2D) = "white"{}
    }
    SubShader
    {
        Pass
        {
            CGPROGRAM
            //在CG中调用属性变量
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"

            //定义顶点着色器的输入结构体
            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };
            //定义顶点着色器的输出结构体
            struct v2f
            {
                float4 position : SV_POSITION;
                float2 texcoord : TEXCOORD0;
            };
            fixed4 _MainColor;
            sampler2D _MainTex;
            float4 _MainTex_ST;
            void vert (in appdata v, out v2f o)
            {
                o.position = UnityObjectToClipPos(v.vertex);
                o.texcoord = v.uv * _MainTex_ST.xy + _MainTex_ST.zw;
            }

            void frag(in v2f i ,out fixed4 color : SV_TARGET)
            {
                color = tex2D(_MainTex,i.texcoord) * _MainColor;
            }
            ENDCG
        }
    }
    Fallback "Diffuse"
}

有返回值

        Pass
        {
            CGPROGRAM
            //在CG中调用属性变量
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"

            //定义顶点着色器的输入结构体
            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };
            //定义顶点着色器的输出结构体
            struct v2f
            {
                float4 position : SV_POSITION;
                float2 texcoord : TEXCOORD0;
            };
            fixed4 _MainColor;
            sampler2D _MainTex;
            float4 _MainTex_ST;
            v2f vert (appdata v)
            {
                v2f o;
                o.position = UnityObjectToClipPos(v.vertex);
                o.texcoord = v.uv * _MainTex_ST.xy + _MainTex_ST.zw;
                return o;
            }

            fixed4 frag(v2f i) : SV_TARGET
            {
                return tex2D(_MainTex,i.texcoord) * _MainColor;               
            }
            ENDCG
        }