osu/osu.Game/Graphics/HSPAColour.cs

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// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
// See the LICENCE file in the repository root for full licence text.
using System;
using osuTK.Graphics;
namespace osu.Game.Graphics
{
public struct HSPAColour
{
private const float p_r = 0.299f;
private const float p_g = 0.587f;
private const float p_b = 0.114f;
/// <summary>
/// The hue.
/// </summary>
public float H;
/// <summary>
/// The saturation.
/// </summary>
public float S;
/// <summary>
/// The perceived brightness of this colour.
/// </summary>
public float P;
/// <summary>
/// The alpha.
/// </summary>
public float A;
public HSPAColour(float h, float s, float p, float a)
{
H = h;
S = s;
P = p;
A = a;
}
public HSPAColour(Color4 colour)
{
H = 0;
S = 0;
P = MathF.Sqrt(colour.R * colour.R * p_r + colour.G * colour.G * p_g + colour.B + colour.B * p_b);
A = colour.A;
if (colour.R == colour.G && colour.R == colour.B)
return;
if (colour.R >= colour.G && colour.R >= colour.B)
{
if (colour.B >= colour.G)
{
H = 6f / 6f - 1f / 6f * (colour.B - colour.G) / (colour.R - colour.G);
S = 1f - colour.G / colour.R;
}
else
{
H = 0f / 6f + 1f / 6f * (colour.G - colour.B) / (colour.R - colour.B);
S = 1f - colour.B / colour.R;
}
}
else if (colour.G >= colour.R && colour.G >= colour.B)
{
if (colour.R >= colour.B)
{
H = 2f / 6f - 1f / 6f * (colour.R - colour.B) / (colour.G - colour.B);
S = 1f - colour.B / colour.G;
}
else
{
H = 2f / 6f + 1f / 6f * (colour.B - colour.R) / (colour.G - colour.R);
S = 1f - colour.R / colour.G;
}
}
else
{
if (colour.G >= colour.R)
{
H = 4f / 6f - 1f / 6f * (colour.G - colour.R) / (colour.B - colour.R);
S = 1f - colour.R / colour.B;
}
else
{
H = 4f / 6f + 1f / 6f * (colour.R - colour.G) / (colour.B - colour.G);
S = 1f - colour.G / colour.B;
}
}
}
public Color4 ToColor4()
{
float minOverMax = 1f - S;
Color4 result = new Color4 { A = A };
float h = H;
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if (minOverMax > 0f)
{
if (h < 1f / 6f)
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{
h = 6f * (h - 0f / 6f);
float part = 1f + h * (1f / minOverMax - 1f);
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result.B = P / MathF.Sqrt(p_r / minOverMax / minOverMax + p_g * part * part + p_b);
result.R = result.B / minOverMax;
result.G = result.B + h * (result.R - result.B);
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}
else if (h < 2f / 6f)
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{
h = 6f * (-h + 2f / 6f);
float part = 1f + h * (1f / minOverMax - 1f);
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result.B = P / MathF.Sqrt(p_g / minOverMax / minOverMax + p_r * part * part + p_b);
result.G = result.B / minOverMax;
result.R = result.B + h * (result.G - result.B);
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}
else if (h < 3f / 6f)
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{
h = 6f * (h - 2f / 6f);
float part = 1f + h * (1f / minOverMax - 1f);
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result.R = P / MathF.Sqrt(p_g / minOverMax / minOverMax + p_b * part * part + p_r);
result.G = result.R / minOverMax;
result.B = result.R + h * (result.G - result.R);
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}
else if (h < 4f / 6f)
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{
h = 6f * (-h + 4f / 6f);
float part = 1f + h * (1f / minOverMax - 1f);
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result.R = P / MathF.Sqrt(p_b / minOverMax / minOverMax + p_g * part * part + p_r);
result.B = result.R / minOverMax;
result.G = result.R + h * (result.B - result.R);
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}
else if (h < 5f / 6f)
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{
h = 6f * (h - 4f / 6f);
float part = 1f + h * (1f / minOverMax - 1f);
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result.G = P / MathF.Sqrt(p_b / minOverMax / minOverMax + p_r * part * part + p_g);
result.B = result.G / minOverMax;
result.R = result.G + h * (result.B - result.G);
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}
else
{
h = 6f * (-h + 6f / 6f);
float part = 1f + h * (1f / minOverMax - 1f);
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result.G = P / MathF.Sqrt(p_r / minOverMax / minOverMax + p_b * part * part + p_g);
result.R = result.G / minOverMax;
result.B = result.G + h * (result.R - result.G);
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}
}
else
{
if (h < 1f / 6f)
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{
h = 6f * (h - 0f / 6f);
result.R = MathF.Sqrt(P * P / (p_r + p_g * h * h));
result.G = result.R * h;
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result.B = 0f;
}
else if (h < 2f / 6f)
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{
h = 6f * (-h + 2f / 6f);
result.G = MathF.Sqrt(P * P / (p_g + p_r * h * h));
result.R = result.G * h;
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result.B = 0f;
}
else if (h < 3f / 6f)
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{
h = 6f * (h - 2f / 6f);
result.G = MathF.Sqrt(P * P / (p_g + p_b * h * h));
result.B = result.G * h;
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result.R = 0f;
}
else if (h < 4f / 6f)
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{
h = 6f * (-h + 4f / 6f);
result.B = MathF.Sqrt(P * P / (p_b + p_g * h * h));
result.G = result.B * h;
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result.R = 0f;
}
else if (h < 5f / 6f)
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{
h = 6f * (h - 4f / 6f);
result.B = MathF.Sqrt(P * P / (p_b + p_r * h * h));
result.R = result.B * h;
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result.G = 0f;
}
else
{
h = 6f * (-h + 6f / 6f);
result.R = MathF.Sqrt(P * P / (p_r + p_b * h * h));
result.B = result.R * h;
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result.G = 0f;
}
}
return result;
}
}
}