texture tex0;
sampler sBase=sampler_state{Texture=(tex0);};
float Angle = 0.0;

#define PI 3.14159265f

float4 ps1(float2 Base:TEXCOORD0):COLOR
{
    float4 color = tex2D( sBase, Base.xy );
    if( color.a != 0.0)
    {
        float2 vec1 = float2( 0.5, 1.0 );
        float2 vec2 = normalize( float2( 0.5 - Base.x, 0.5 - Base.y ) );
        float VecAngle = PI + atan2( vec1.x * vec2.y - vec1.y * vec2.x, dot( vec1, vec2 ) );
        if( VecAngle > radians( Angle ) )
            color.a = 0.0;
    }
    return color;
}

technique remover
{
    pass p0
    {
        PixelShader=compile ps_2_0 ps1();
    }
}