package com.bartsent.simpleresizer.lib

import kotlin.math.PI
import kotlin.math.abs
import kotlin.math.sin

object LanczosKernel: ScalingKernel {
    override val size = 3.0

    private fun sinc(x: Double): Double {
        if (x == 0.0)
            return 1.0
        val pix = PI * x
        return sin(pix) / pix
    }

    override fun weight(x: Double): Double =
        if (abs(x) < size) sinc(x) * sinc(x/size) else 0.0
}