Unity Twist Effect Black Hole

Shader "Hidden/Twist Effect" {
Properties {
_MainTex ("Base (RGB)", 2D) = "white" {}
}

SubShader
{
Pass
{
ZTest Always Cull Off ZWrite Off
Fog { Mode off }

CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma fragmentoption ARB_precision_hint_fastest

#include "UnityCG.cginc"

uniform sampler2D _MainTex;

uniform float4 _MainTex_ST;

uniform float4 _MainTex_TexelSize;
uniform float _Angle;
uniform float4 _CenterRadius;

inline float TriWave(float x)
{
return abs(frac(x) * 2-1 )-0.5;

}
struct v2f {
float4 pos : POSITION;
float2 uv : TEXCOORD0;
float2 uvOrig : TEXCOORD1;
};

v2f vert (appdata_img v)
{
v2f o;
o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
float2 uv = v.texcoord.xy - _CenterRadius.xy;
o.uv = TRANSFORM_TEX(uv, _MainTex); //MultiplyUV (UNITY_MATRIX_TEXTURE0, uv);
o.uvOrig = uv;
return o;
}

float4 frag (v2f i) : COLOR
{
float2 offset = i.uvOrig;
float t = TriWave(_Time.y * 0.05);
float angle = 1.0 - length(offset / (_CenterRadius.zw*t ));
angle = max (0, angle);
angle = angle * _Angle * t;
float cosLength, sinLength;
sincos (angle, sinLength, cosLength);

float2 uv;
uv.x = cosLength * offset[0] - sinLength * offset[1];
uv.y = sinLength * offset[0] + cosLength * offset[1];
uv += _CenterRadius.xy;

return tex2D(_MainTex, uv) * (1 - abs(angle * 0.5));
}
ENDCG

}
}

Fallback off

}

Shader "Hidden/Twist Effect" {
Properties {
_MainTex ("Base (RGB)", 2D) = "white" {}
}
SubShader
{
Pass
{
ZTest Always Cull Off ZWrite Off
Fog { Mode off }
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma fragmentoption ARB_precision_hint_fastest
#include "UnityCG.cginc"
uniform sampler2D _MainTex;
uniform float4 _MainTex_ST;
uniform float4 _MainTex_TexelSize;
uniform float _Angle;
uniform float4 _CenterRadius;
inline float TriWave(float x)
{
return abs(frac(x) * 2-1 )-0.5;
}
struct v2f {
float4 pos : POSITION;
float2 uv : TEXCOORD0;
float2 uvOrig : TEXCOORD1;
};
v2f vert (appdata_img v)
{
v2f o;
o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
float2 uv = v.texcoord.xy - _CenterRadius.xy;
o.uv = TRANSFORM_TEX(uv, _MainTex); //MultiplyUV (UNITY_MATRIX_TEXTURE0, uv);
o.uvOrig = uv;
return o;
}
float4 frag (v2f i) : COLOR
{

float t = clamp(TriWave(_Time.y * 0.05), 0.3, 0.8);
float2 offset = i.uvOrig;
float angle = 1.0 - length(offset / (_CenterRadius.zw *t));
float a = angle;
angle += _Time.y;
angle = max (0, angle);
angle = angle * _Angle;
float cosLength, sinLength;
sincos (angle, sinLength, cosLength);

float2 uv;
uv.x = cosLength * offset[0] - sinLength * offset[1];
uv.y = sinLength * offset[0] + cosLength * offset[1];
uv += _CenterRadius.xy;

return tex2D(_MainTex, uv) * (1 - abs(a * 0.5));//(abs(a * 0.5)-1) //black hole
}
ENDCG
}
}
Fallback off
}

Combine with NeoOcean in vertex shader

inline void Vortex(inout half3 localSpaceVertex)
{
half3 vortexC = mul(_World2Object, half4(_LocalVortex.x, 0, _LocalVortex.z,1)).xyz;
half2 offset = localSpaceVertex.xz - vortexC.xz;
half angle = max(0,1.0 - length(offset / (_LocalVortex.ww)));
half rot = -angle * 6.28;
half rotcos, rotsin;
sincos (rot, rotsin, rotcos);
localSpaceVertex.x = vortexC.x + rotcos * offset.x - rotsin * offset.y;
localSpaceVertex.y += _LocalVortex.y * angle;
localSpaceVertex.z = vortexC.z + rotsin * offset.x + rotcos * offset.y;
}