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simpler light tone mapping

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minjaesong
2024-02-03 15:13:33 +09:00
parent f91fbf6cf0
commit 808862c520
3 changed files with 49 additions and 57 deletions
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27
src/net/torvald/terrarum/audio/dsp/SoftClp.kt
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@@ -3,6 +3,7 @@ package net.torvald.terrarum.audio.dsp
import com.badlogic.gdx.graphics.g2d.SpriteBatch
import kotlin.math.absoluteValue
import kotlin.math.pow
import kotlin.math.sign
import kotlin.math.sqrt
/**
@@ -36,31 +37,29 @@ object SoftClp : TerrarumAudioFilter(), DspCompressor {
}
}
// private const val clip_p = 0.277777f // knee of around -1.94dB
private const val clip_p = 0.349f // knee of around -3.01dB
// private const val clip_p = 0.44444f // knee of around -6.02dB
private val clip_p1 = sqrt(1.0f - 2.0f * clip_p)
private val clip_lim = 1.0f / (1.0f + clip_p1)
/**
* https://www.desmos.com/calculator/syqd1byzzl
* @param x0 -0.5..0.5 ish
* @return -0.5..0.5
*/
private fun clipfun0(x0: Double): Double {
// val p = 0.277777 // knee of around -1.94dB
val p = 0.349 // knee of around -3.01dB
// val p = 0.44444 // knee of around -6.02dB
val p1 = sqrt(1.0 - 2.0 * p)
val x = x0 * (1.0f + clip_p1) / 2.0f
val t = 0.5f * clip_p1
val x = x0 * (1.0 + p1) / 2.0
val t = 0.5 * p1
val lim = 1.0 / (1.0 + p1)
if (x0 >= lim) return 0.5
if (x0 <= -lim) return -0.5
if (x0.absoluteValue >= clip_lim) return 0.5f * sign(x0)
val y0 = if (x < -t)
(1.0 / p) * (x + 0.5).pow(2) - 0.5
(x*x + x + 0.25f) / clip_p - 0.5f
else if (x > t)
-(1.0 / p) * (x - 0.5).pow(2) + 0.5
-(x*x - x + 0.25f) / clip_p + 0.5f
else
x * 2.0 * lim
x * 2.0f * clip_lim
return y0
}