shader

Shader "Custom/Area Fan"
{
Properties
{
_Color ("Main Color", Color) = (1,1,1,1)
_Angle ("Angle", Float) = 360.0
}
SubShader
{
Tags
{ 
"Queue" = "Transparent"
"IgnoreProjector" = "True"
"RenderType" = "Transparent"
}
    Pass {
Lighting Off
ZWrite Off
Blend SrcAlpha OneMinusSrcAlpha
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma fragmentoption ARB_fog_exp2
#include "UnityCG.cginc"


float4 _Color;
float _Angle;
struct v2f {
   float4 pos : SV_POSITION;
   float2 texcoord: TEXCOORD0;
};

v2f vert (appdata_base v)
{
   v2f o;
   o.pos = mul (UNITY_MATRIX_MVP, v.vertex);
   o.texcoord = v.texcoord;
   return o;
}


float4 frag (v2f i) : COLOR
{
float2 tex_pos = i.texcoord - float2(0.5,0.5);
float rad = atan2( tex_pos.x,tex_pos.y );
float alpha = _Color.a;
if ( rad > radians( _Angle - 180 ) )
{
alpha = 0;
}
else
{
float area_length = tex_pos.x * tex_pos.x + tex_pos.y * tex_pos.y;
alpha =  area_length > 0.25 ? 0 : alpha * area_length / 0.25;
}
return float4( _Color.rgb, alpha );
}

ENDCG


    }
}


Fallback "VertexLit"
}