旋转扭曲特效是指在一个圆形区域内扭曲所渲染的图像，其他像素的旋转程度随着距离的变化而变化。具体可以通过修改Shader来实现。
原始图片
扭曲图片
/*====================================================
屏幕扭曲特效Shader
======================================================*/
Shader "Hidden/TwirlEffects"
{
Properties
{
_MainTex ("Texture", 2D) = "white" {}
}
SubShader
{
// No culling or depth
Cull Off ZWrite Off ZTest Always
Pass
{
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"
uniform sampler2D _MainTex;
uniform float4 _MainTex_TexelSize;
half4 _MainTex_ST;
//旋转扭曲的中心
uniform float4 _CenterRadius;
//将旋转矩阵传入
uniform float4x4 _RotationMatrix;
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 = mul(UNITY_MATRIX_MVP, v.vertex);
//将uv坐标变换到center坐标系中
o.uv = v.uv - _CenterRadius.xy;
return o;
}
fixed4 frag (v2f i) : SV_Target
{
float2 offest = i.uv;
//利用旋转矩阵旋转uv
float2 distortedOffset = MultiplyUV(_RotationMatrix,offest.xy);
//计算uv点在旋转圆中的位置
float2 tmp = offest / _CenterRadius.zw;
float t = min(1,length(tmp));
//根据uv点在圆中的位置插值uv移动的位置
offest =lerp(distortedOffset,offest,t);
//将uv坐标返回原坐标系中
offest += _CenterRadius.xy;
fixed4 col = tex2D(_MainTex, UnityStereoScreenSpaceUVAdjust(offest, _MainTex_ST));
return col;
}
ENDCG
}
}
}
此旋转特效主要就是对图像的uv值进行偏移，关键代码
float2 offest = i.uv; //利用旋转矩阵旋转uv float2 distortedOffset = MultiplyUV(_RotationMatrix,offest.xy); //计算uv点在旋转圆中的位置 float2 tmp = offest / _CenterRadius.zw; float t = min(1,length(tmp)); //根据uv点在圆中的位置插值uv移动的位置 offest =lerp(distortedOffset,offest,t); //将uv坐标返回原坐标系中 offest += _CenterRadius.xy;
根据uv点的位置，对图像进行扭曲。
下面是脚本的源码
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class TwirlScripts : MonoBehaviour {
[ExecuteInEditMode]
public Vector2 radius = new Vector2(0.3f, 0.3f);
public Vector2 center = new Vector2(0.5f, 0.5f);
[Range(0.0f, 360.0f)]
public float angle = 0.0f;
public Material material;
private void OnRenderImage(RenderTexture source, RenderTexture destination)
{
Matrix4x4 rotationMatrix = Matrix4x4.TRS(Vector3.zero, Quaternion.Euler(0, 0, angle), Vector3.one);
material.SetMatrix("_RotationMatrix", rotationMatrix);
material.SetVector("_CenterRadius", new Vector4(center.x, center.y, radius.x, radius.y));
Graphics.Blit(source, destination, material);
}
}
