旋轉公式為矩陣的旋轉公式，具體可以自行百度，這裡博主不在詳細解釋。

Shader "Hidden/TestStruct"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}
		_Speed("Speed",float)=1
	}
	SubShader
	{

		Pass
		{
			CGPROGRAM  
			#pragma vertex vert  
			#pragma fragment frag	
			
			#include "UnityCG.cginc"	
			float _Speed;
			sampler2D _MainTex;
			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;
			}
			
			
			fixed4 frag (v2f i) : SV_Target	
			{
				float2 tempUV = i.uv;

				//平移到原點位置
				tempUV -= float2(0.5, 0.5);
				//旋轉
				float angle = _Time.x*_Speed;
				float2 finalUV = 0;
				finalUV.x = tempUV.x*cos(angle) - tempUV.y*sin(angle);
				finalUV.y = tempUV.x*sin(angle) + tempUV.y*cos(angle);

				//平移回圖片原位置
				finalUV+= float2(0.5, 0.5);
				return tex2D(_MainTex, finalUV);
			}
			ENDCG
		}
	}
}