[游戏开发]Unity UV基于中心点旋转/缩放/位移 Shader

先上效果图:

?接下来是参数控制面板:

?再接下来是代码:

Shader "Unlit/UV_R_S_T"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}
		[Toggle(OpenScale)]_OpenScale("OpenScale",float)=0
		_Scale("Scale",Range(0,10)) = 1
		[Toggle(OpenRotate)]_OpenRotate("OpenScale",float)=0
		_Rotate("Rotate",float) = 0
		[Toggle(OpenOffset)]_OpenOffset("OpenOffset",float)=0
		_Offset("Offset",float) =(0,0,0,0)
	}
	SubShader
	{
		Tags { "RenderType"="Opaque" }
		LOD 100

		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;
			};

			sampler2D _MainTex;
			float4 _MainTex_ST;
			float _OpenScale;
			float _Scale;
			float _OpenRotate;
			float _Rotate;
			float _OpenOffset;
			float4 _Offset;
			
			v2f vert (appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.uv = TRANSFORM_TEX(v.uv, _MainTex);
				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{
				float2 newUV = i.uv;
				if(_OpenScale)
				{
					newUV -= float2(0.5,0.5);
					newUV *= _Scale;
					newUV += float2(0.5,0.5);
				}
				if(_OpenRotate)
				{
					float angle = _Rotate*0.017453292519943295;
					newUV -= float2(0.5,0.5);
					newUV = float2(newUV.x*cos(angle)-newUV.y*sin(angle),newUV.y*cos(angle) + newUV.x*sin(angle));
					newUV += float2(0.5,0.5);
				}
				if(_OpenOffset)newUV += _Offset.xy;
				fixed4 col = tex2D(_MainTex, newUV);
				return col;
			}
			ENDCG
		}
	}
}

技术难点在于如何让UV至于中心点并且可以旋转，缩放.

需要先把? uv -= float2(0.5,0.5);? UV的中心点移动到中间?然后在此基础上做旋转，缩放等操作后再把 uv += float2(0.5,0.5);? ?表面看上去先减0.5?然后再加0.5像是什么也没有做?但是在+0.5之前进行过的操作就会被记录在uv里?然后在操作后的基础上把UV再加回去一半就可以实现中心点操作了.(0.5代表的是UV一半?因为UV本身是0-1的映射)

如果有不明白的可以把工程下载下来查看!

https://download.csdn.net/download/haseef520s/20680741