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https://gitea.com/Sirherobrine23/tea.git
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208 lines
6.0 KiB
Go
208 lines
6.0 KiB
Go
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package colorful
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import "math"
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// Source: https://github.com/hsluv/hsluv-go
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// Under MIT License
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// Modified so that Saturation and Luminance are in [0..1] instead of [0..100].
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// HSLuv uses a rounded version of the D65. This has no impact on the final RGB
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// values, but to keep high levels of accuracy for internal operations and when
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// comparing to the test values, this modified white reference is used internally.
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//
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// See this GitHub thread for details on these values:
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// https://github.com/hsluv/hsluv/issues/79
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var hSLuvD65 = [3]float64{0.95045592705167, 1.0, 1.089057750759878}
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func LuvLChToHSLuv(l, c, h float64) (float64, float64, float64) {
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// [-1..1] but the code expects it to be [-100..100]
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c *= 100.0
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l *= 100.0
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var s, max float64
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if l > 99.9999999 || l < 0.00000001 {
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s = 0.0
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} else {
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max = maxChromaForLH(l, h)
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s = c / max * 100.0
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}
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return h, clamp01(s / 100.0), clamp01(l / 100.0)
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}
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func HSLuvToLuvLCh(h, s, l float64) (float64, float64, float64) {
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l *= 100.0
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s *= 100.0
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var c, max float64
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if l > 99.9999999 || l < 0.00000001 {
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c = 0.0
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} else {
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max = maxChromaForLH(l, h)
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c = max / 100.0 * s
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}
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// c is [-100..100], but for LCh it's supposed to be almost [-1..1]
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return clamp01(l / 100.0), c / 100.0, h
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}
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func LuvLChToHPLuv(l, c, h float64) (float64, float64, float64) {
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// [-1..1] but the code expects it to be [-100..100]
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c *= 100.0
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l *= 100.0
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var s, max float64
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if l > 99.9999999 || l < 0.00000001 {
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s = 0.0
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} else {
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max = maxSafeChromaForL(l)
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s = c / max * 100.0
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}
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return h, s / 100.0, l / 100.0
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}
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func HPLuvToLuvLCh(h, s, l float64) (float64, float64, float64) {
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// [-1..1] but the code expects it to be [-100..100]
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l *= 100.0
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s *= 100.0
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var c, max float64
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if l > 99.9999999 || l < 0.00000001 {
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c = 0.0
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} else {
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max = maxSafeChromaForL(l)
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c = max / 100.0 * s
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}
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return l / 100.0, c / 100.0, h
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}
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// HSLuv creates a new Color from values in the HSLuv color space.
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// Hue in [0..360], a Saturation [0..1], and a Luminance (lightness) in [0..1].
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//
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// The returned color values are clamped (using .Clamped), so this will never output
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// an invalid color.
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func HSLuv(h, s, l float64) Color {
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// HSLuv -> LuvLCh -> CIELUV -> CIEXYZ -> Linear RGB -> sRGB
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l, u, v := LuvLChToLuv(HSLuvToLuvLCh(h, s, l))
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return LinearRgb(XyzToLinearRgb(LuvToXyzWhiteRef(l, u, v, hSLuvD65))).Clamped()
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}
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// HPLuv creates a new Color from values in the HPLuv color space.
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// Hue in [0..360], a Saturation [0..1], and a Luminance (lightness) in [0..1].
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//
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// The returned color values are clamped (using .Clamped), so this will never output
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// an invalid color.
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func HPLuv(h, s, l float64) Color {
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// HPLuv -> LuvLCh -> CIELUV -> CIEXYZ -> Linear RGB -> sRGB
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l, u, v := LuvLChToLuv(HPLuvToLuvLCh(h, s, l))
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return LinearRgb(XyzToLinearRgb(LuvToXyzWhiteRef(l, u, v, hSLuvD65))).Clamped()
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}
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// HSLuv returns the Hue, Saturation and Luminance of the color in the HSLuv
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// color space. Hue in [0..360], a Saturation [0..1], and a Luminance
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// (lightness) in [0..1].
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func (col Color) HSLuv() (h, s, l float64) {
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// sRGB -> Linear RGB -> CIEXYZ -> CIELUV -> LuvLCh -> HSLuv
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return LuvLChToHSLuv(col.LuvLChWhiteRef(hSLuvD65))
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}
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// HPLuv returns the Hue, Saturation and Luminance of the color in the HSLuv
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// color space. Hue in [0..360], a Saturation [0..1], and a Luminance
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// (lightness) in [0..1].
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//
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// Note that HPLuv can only represent pastel colors, and so the Saturation
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// value could be much larger than 1 for colors it can't represent.
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func (col Color) HPLuv() (h, s, l float64) {
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return LuvLChToHPLuv(col.LuvLChWhiteRef(hSLuvD65))
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}
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// DistanceHSLuv calculates Euclidan distance in the HSLuv colorspace. No idea
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// how useful this is.
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//
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// The Hue value is divided by 100 before the calculation, so that H, S, and L
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// have the same relative ranges.
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func (c1 Color) DistanceHSLuv(c2 Color) float64 {
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h1, s1, l1 := c1.HSLuv()
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h2, s2, l2 := c2.HSLuv()
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return math.Sqrt(sq((h1-h2)/100.0) + sq(s1-s2) + sq(l1-l2))
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}
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// DistanceHPLuv calculates Euclidean distance in the HPLuv colorspace. No idea
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// how useful this is.
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//
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// The Hue value is divided by 100 before the calculation, so that H, S, and L
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// have the same relative ranges.
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func (c1 Color) DistanceHPLuv(c2 Color) float64 {
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h1, s1, l1 := c1.HPLuv()
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h2, s2, l2 := c2.HPLuv()
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return math.Sqrt(sq((h1-h2)/100.0) + sq(s1-s2) + sq(l1-l2))
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}
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var m = [3][3]float64{
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{3.2409699419045214, -1.5373831775700935, -0.49861076029300328},
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{-0.96924363628087983, 1.8759675015077207, 0.041555057407175613},
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{0.055630079696993609, -0.20397695888897657, 1.0569715142428786},
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}
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const kappa = 903.2962962962963
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const epsilon = 0.0088564516790356308
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func maxChromaForLH(l, h float64) float64 {
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hRad := h / 360.0 * math.Pi * 2.0
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minLength := math.MaxFloat64
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for _, line := range getBounds(l) {
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length := lengthOfRayUntilIntersect(hRad, line[0], line[1])
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if length > 0.0 && length < minLength {
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minLength = length
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}
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}
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return minLength
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}
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func getBounds(l float64) [6][2]float64 {
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var sub2 float64
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var ret [6][2]float64
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sub1 := math.Pow(l+16.0, 3.0) / 1560896.0
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if sub1 > epsilon {
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sub2 = sub1
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} else {
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sub2 = l / kappa
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}
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for i := range m {
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for k := 0; k < 2; k++ {
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top1 := (284517.0*m[i][0] - 94839.0*m[i][2]) * sub2
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top2 := (838422.0*m[i][2]+769860.0*m[i][1]+731718.0*m[i][0])*l*sub2 - 769860.0*float64(k)*l
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bottom := (632260.0*m[i][2]-126452.0*m[i][1])*sub2 + 126452.0*float64(k)
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ret[i*2+k][0] = top1 / bottom
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ret[i*2+k][1] = top2 / bottom
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}
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}
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return ret
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}
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func lengthOfRayUntilIntersect(theta, x, y float64) (length float64) {
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length = y / (math.Sin(theta) - x*math.Cos(theta))
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return
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}
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func maxSafeChromaForL(l float64) float64 {
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minLength := math.MaxFloat64
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for _, line := range getBounds(l) {
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m1 := line[0]
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b1 := line[1]
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x := intersectLineLine(m1, b1, -1.0/m1, 0.0)
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dist := distanceFromPole(x, b1+x*m1)
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if dist < minLength {
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minLength = dist
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}
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}
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return minLength
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}
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func intersectLineLine(x1, y1, x2, y2 float64) float64 {
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return (y1 - y2) / (x2 - x1)
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}
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func distanceFromPole(x, y float64) float64 {
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return math.Sqrt(math.Pow(x, 2.0) + math.Pow(y, 2.0))
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}
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