gamma: switch to wlsunset-style transitions

core/internal/server/wayland/gamma.go

@@ -2,8 +2,6 @@ package wayland
 
 import (
 	"math"
-
-	"github.com/AvengeMedia/DankMaterialShell/core/internal/utils"
 )
 
 type GammaRamp struct {
@@ -12,6 +10,126 @@ type GammaRamp struct {
 	Blue  []uint16
 }
 
+type rgb struct {
+	r, g, b float64
+}
+
+type xyz struct {
+	x, y, z float64
+}
+
+func illuminantD(temp int) (float64, float64, bool) {
+	var x float64
+	switch {
+	case temp >= 2500 && temp <= 7000:
+		t := float64(temp)
+		x = 0.244063 + 0.09911e3/t + 2.9678e6/(t*t) - 4.6070e9/(t*t*t)
+	case temp > 7000 && temp <= 25000:
+		t := float64(temp)
+		x = 0.237040 + 0.24748e3/t + 1.9018e6/(t*t) - 2.0064e9/(t*t*t)
+	default:
+		return 0, 0, false
+	}
+	y := -3*(x*x) + 2.870*x - 0.275
+	return x, y, true
+}
+
+func planckianLocus(temp int) (float64, float64, bool) {
+	var x, y float64
+	switch {
+	case temp >= 1667 && temp <= 4000:
+		t := float64(temp)
+		x = -0.2661239e9/(t*t*t) - 0.2343589e6/(t*t) + 0.8776956e3/t + 0.179910
+		if temp <= 2222 {
+			y = -1.1064814*(x*x*x) - 1.34811020*(x*x) + 2.18555832*x - 0.20219683
+		} else {
+			y = -0.9549476*(x*x*x) - 1.37418593*(x*x) + 2.09137015*x - 0.16748867
+		}
+	case temp > 4000 && temp < 25000:
+		t := float64(temp)
+		x = -3.0258469e9/(t*t*t) + 2.1070379e6/(t*t) + 0.2226347e3/t + 0.240390
+		y = 3.0817580*(x*x*x) - 5.87338670*(x*x) + 3.75112997*x - 0.37001483
+	default:
+		return 0, 0, false
+	}
+	return x, y, true
+}
+
+func srgbGamma(value, gamma float64) float64 {
+	if value <= 0.0031308 {
+		return 12.92 * value
+	}
+	return math.Pow(1.055*value, 1.0/gamma) - 0.055
+}
+
+func clamp01(v float64) float64 {
+	switch {
+	case v > 1.0:
+		return 1.0
+	case v < 0.0:
+		return 0.0
+	default:
+		return v
+	}
+}
+
+func xyzToSRGB(c xyz) rgb {
+	return rgb{
+		r: srgbGamma(clamp01(3.2404542*c.x-1.5371385*c.y-0.4985314*c.z), 2.2),
+		g: srgbGamma(clamp01(-0.9692660*c.x+1.8760108*c.y+0.0415560*c.z), 2.2),
+		b: srgbGamma(clamp01(0.0556434*c.x-0.2040259*c.y+1.0572252*c.z), 2.2),
+	}
+}
+
+func normalizeRGB(c *rgb) {
+	maxw := math.Max(c.r, math.Max(c.g, c.b))
+	if maxw > 0 {
+		c.r /= maxw
+		c.g /= maxw
+		c.b /= maxw
+	}
+}
+
+func calcWhitepoint(temp int) rgb {
+	if temp == 6500 {
+		return rgb{r: 1.0, g: 1.0, b: 1.0}
+	}
+
+	var wp xyz
+
+	switch {
+	case temp >= 25000:
+		x, y, _ := illuminantD(25000)
+		wp.x = x
+		wp.y = y
+	case temp >= 4000:
+		x, y, _ := illuminantD(temp)
+		wp.x = x
+		wp.y = y
+	case temp >= 2500:
+		x1, y1, _ := illuminantD(temp)
+		x2, y2, _ := planckianLocus(temp)
+		factor := float64(4000-temp) / 1500.0
+		sineFactor := (math.Cos(math.Pi*factor) + 1.0) / 2.0
+		wp.x = x1*sineFactor + x2*(1.0-sineFactor)
+		wp.y = y1*sineFactor + y2*(1.0-sineFactor)
+	default:
+		t := temp
+		if t < 1667 {
+			t = 1667
+		}
+		x, y, _ := planckianLocus(t)
+		wp.x = x
+		wp.y = y
+	}
+
+	wp.z = 1.0 - wp.x - wp.y
+
+	wpRGB := xyzToSRGB(wp)
+	normalizeRGB(&wpRGB)
+	return wpRGB
+}
+
 func GenerateGammaRamp(size uint32, temp int, gamma float64) GammaRamp {
 	ramp := GammaRamp{
 		Red:   make([]uint16, size),
@@ -19,16 +137,13 @@ func GenerateGammaRamp(size uint32, temp int, gamma float64) GammaRamp {
 		Blue:  make([]uint16, size),
 	}
 
+	wp := calcWhitepoint(temp)
+
 	for i := uint32(0); i < size; i++ {
 		val := float64(i) / float64(size-1)
-
-		valGamma := math.Pow(val, 1.0/gamma)
-
-		r, g, b := temperatureToRGB(temp)
-
-		ramp.Red[i] = uint16(utils.Clamp(valGamma*r*65535.0, 0, 65535))
-		ramp.Green[i] = uint16(utils.Clamp(valGamma*g*65535.0, 0, 65535))
-		ramp.Blue[i] = uint16(utils.Clamp(valGamma*b*65535.0, 0, 65535))
+		ramp.Red[i] = uint16(clamp01(math.Pow(val*wp.r, 1.0/gamma)) * 65535.0)
+		ramp.Green[i] = uint16(clamp01(math.Pow(val*wp.g, 1.0/gamma)) * 65535.0)
+		ramp.Blue[i] = uint16(clamp01(math.Pow(val*wp.b, 1.0/gamma)) * 65535.0)
 	}
 
 	return ramp
@@ -50,39 +165,3 @@ func GenerateIdentityRamp(size uint32) GammaRamp {
 
 	return ramp
 }
-
-func temperatureToRGB(temp int) (float64, float64, float64) {
-	tempK := float64(temp) / 100.0
-
-	var r, g, b float64
-
-	if tempK <= 66 {
-		r = 1.0
-	} else {
-		r = tempK - 60
-		r = 329.698727446 * math.Pow(r, -0.1332047592)
-		r = utils.Clamp(r, 0, 255) / 255.0
-	}
-
-	if tempK <= 66 {
-		g = tempK
-		g = 99.4708025861*math.Log(g) - 161.1195681661
-		g = utils.Clamp(g, 0, 255) / 255.0
-	} else {
-		g = tempK - 60
-		g = 288.1221695283 * math.Pow(g, -0.0755148492)
-		g = utils.Clamp(g, 0, 255) / 255.0
-	}
-
-	if tempK >= 66 {
-		b = 1.0
-	} else if tempK <= 19 {
-		b = 0.0
-	} else {
-		b = tempK - 10
-		b = 138.5177312231*math.Log(b) - 305.0447927307
-		b = utils.Clamp(b, 0, 255) / 255.0
-	}
-
-	return r, g, b
-}