Twirl是一个全屏画面扭曲的效果，新仙剑的战斗切换有用到这个效果。
主要有三个设置:
center扭曲的中心点
radius扭曲的范围
angle扭曲的角度
用到了如下函数
Matrix4x4.TRS(Vector3 pos, Quaternion rotate,Vector3 scale)
创建一个包括位移，旋转，缩放的矩阵
Matrix4x4rotationMatrix =Matrix4x4.TRS(Vector3.zero,Quaternion.Euler(0,0, angle),Vector3.one);
然后通过material的以下函数向shader里传参数
material.SetMatrix("name",value)对应Shader里的 float4x4
material.SetVector("name",value)对应Shader里的 float4
float2 MultiplyUV (float4x4 mat, float2 inUV) {
float4 temp = float4 (inUV.x, inUV.y, 0, 0);
temp = mul (mat, temp);
return temp.xy;
}
步骤:
脚本
(1) 通过Angle得到旋转矩阵
Matrix4x4rotationMatrix =Matrix4x4.TRS(Vector3.zero,Quaternion.Euler(0,0, angle),Vector3.one);
(2) 将矩阵和 旋转中点 及 半径传入shader.
Shader
(1) 将坐标系从左下角的坐标系 转到 以旋转中点为 原点的坐标系
vert里 o.uv = v.texcoord- _CenterRadius.xy;
(2) 将旋转坐标系 里的uv乘以 旋转矩阵。
(3) 将uv除以 半径， 再取长度。长度超过1则为 旋转区域外，小于则在区域内
(4) 如果在区域外，则为默认offset, 在内则是旋转后的offset
脚本
usingUnityEngine;
usingSystem.Collections;
public classTwirlEffectMe :MonoBehaviour{
public Shadershader;
private Materialmat;
public Vector2radius =new Vector2(0.3F,0.3F);
publicfloatangle =50;
public Vector2center =new Vector2(0.5F,0.5F);
voidStart()
{
mat =newMaterial(shader);
}
voidOnRenderImage (RenderTexturesource,RenderTexturedestination) {
RenderDistortion (mat, source, destination, angle, center, radius);
}
publicstaticvoidRenderDistortion(Materialmaterial,RenderTexturesource,RenderTexturedestination,floatangle,Vector2center,Vector2radius)
{
Matrix4x4rotationMatrix =Matrix4x4.TRS(Vector3.zero,Quaternion.Euler(0,0, angle),Vector3.one);
material.SetMatrix("_RotationMatrix", rotationMatrix);
material.SetVector("_CenterRadius",newVector4(center.x, center.y, radius.x, radius.y));
Graphics.Blit(source, destination, material);
}
}
Shader脚本
Shader"Custom/TwirlEffectMe"{
Properties{
_MainTex ("Base (RGB)",2D) ="white"{}
}
SubShader{
Pass{
ZTestAlwaysCullOffZWriteOff
Fog{Modeoff}
CGPROGRAM
#pragmavertex vert
#pragmafragment frag
#include"UnityCG.cginc"
uniformsampler2D_MainTex;
uniformfloat4_MainTex_TexelSize;
uniformfloat4_CenterRadius;
uniformfloat4x4_RotationMatrix;
structv2f {
float4pos : POSITION;
float2uv :TEXCOORD0;
} ;
v2f vert( appdata_img v )
{
v2f o;
o.pos =mul(UNITY_MATRIX_MVP, v.vertex);
o.uv = v.texcoord- _CenterRadius.xy;
returno;
}
float4frag (v2f i) :COLOR
{
float2offset= i.uv;
float2distortedOffset = MultiplyUV (_RotationMatrix,offset.xy);
float2tmp =offset/ _CenterRadius.zw;
float2finalUV;
floatlen =length(tmp);
// out of twirl
if( len >1)
{
finalUV =offset;
}
else
{
finalUV =distortedOffset;
}
// back to normal uv coordinate
finalUV += _CenterRadius.xy;
returntex2D(_MainTex, finalUV);
}
ENDCG
}
}
Fallbackoff
}
但是运行后，发现仅仅是简单旋转。需要再加上模糊。
分析一下，发现是由内向外从distortedOffset 渐渐向 正常offset过度的过程
于是将43行的finalUV =distortedOffset;改为
finalUV =lerp(distortedOffset,offset, len );
整体代码如下：
Shader"Custom/TwirlEffectMe"{
Properties{
_MainTex ("Base (RGB)",2D) ="white"{}
}
SubShader{
Pass{
ZTestAlwaysCullOffZWriteOff
Fog{Modeoff}
CGPROGRAM
#pragmavertex vert
#pragmafragment frag
#include"UnityCG.cginc"
uniform sampler2D_MainTex;
uniformfloat4_MainTex_TexelSize;
uniformfloat4_CenterRadius;
uniformfloat4x4_RotationMatrix;
structv2f {
float4pos : POSITION;
float2uv :TEXCOORD0;
} ;
v2f vert( appdata_img v )
{
v2f o;
o.pos =mul(UNITY_MATRIX_MVP, v.vertex);
o.uv = v.texcoord- _CenterRadius.xy;
returno;
}
float4frag (v2f i) :COLOR
{
float2offset= i.uv;
float2distortedOffset = MultiplyUV (_RotationMatrix,offset.xy);
float2tmp =offset/ _CenterRadius.zw;
float2finalUV;
floatlen =length(tmp);
// out of twirl
if( len >1)
{
finalUV =offset;
}
else
{
finalUV =lerp(distortedOffset,offset, len );
}
// back to normal uv coordinate
finalUV += _CenterRadius.xy;
returntex2D(_MainTex, finalUV);
}
ENDCG
}
}
Fallbackoff
}
点击运行，效果对了。
