struct PixelInput
{
    float4 position : SV_Position;
    float4 color : COLOR0;
    float2 localPosition : TEXCOORD0;
};

float4 MainPS(PixelInput input) : SV_Target0
{
    float alpha = exp(-dot(input.localPosition, input.localPosition));
    alpha = saturate(alpha * input.color.a);

    if (alpha < (1.0 / 255.0))
    {
        discard;
    }

    return float4(input.color.rgb * alpha, alpha);
}