/// <param name="paletteCount">Min 3.</param>
public ColorGenerator(int paletteCount)
{
if (paletteCount < 3)
return;
// generate at least as many colors that we need
const double exponent = 3;
double a = Math.Pow(paletteCount, 1 / exponent);
double @base = Math.Ceiling(a);
double max = Math.Pow(@base, exponent);
for (int i = 0; i < max; i++)
{
double red = Math.Floor(i / (@base * @base))
/ (@base - 1);
double yellow = Math.Floor((i / @base) % @base)
/ (@base - 1);
double blue = Math.Floor(i % @base)
/ (@base - 1);
RybColor color = new RybColor(red, yellow, blue);
m_colorPalette.Add(color);
}
m_picked = null;
}
/// <summary>
/// Euclidian distance
/// </summary>
public static double DistanceSquared(RybColor color, RybColor other)
{
double redDistance = Math.Pow(color.Red - other.Red, 2);
double yellowDistance = Math.Pow(color.Yellow - other.Yellow, 2);
double blueDistance = Math.Pow(color.Blue - other.Blue, 2);
return redDistance + yellowDistance + blueDistance;
}
public static Color ToColor(RybColor rybColor)
{
Color color = new Color()
{
A = 255,
R = (byte)GetRed(rybColor),
G = (byte)GetGreen(rybColor),
B = (byte)GetBlue(rybColor),
};
return color;
}
private static double GetRed(RybColor rybColor)
{
var iR = rybColor.Red;
var iY = rybColor.Yellow;
var iB = rybColor.Blue;
var x0 = CubicInterpolate(iB, 1.0, 0.163);
var x1 = CubicInterpolate(iB, 1.0, 0.0);
var x2 = CubicInterpolate(iB, 1.0, 0.5);
var x3 = CubicInterpolate(iB, 1.0, 0.2);
var y0 = CubicInterpolate(iY, x0, x1);
var y1 = CubicInterpolate(iY, x2, x3);
return Math.Ceiling(255 * CubicInterpolate(iR, y0, y1));
}
public RybColor PickNextColor()
{
if (m_picked == null)
{
m_picked = m_colorPalette.FirstOrDefault();
if (m_picked == null)
return null;
m_colorPalette.RemoveAt(0);
Debug.WriteLine("Initial color is {0}", m_picked);
m_pickedColorCount = 1;
return m_picked;
}
// pick (close to) the color that is farthest away from the last picked color
var result = m_colorPalette.Aggregate<RybColor,Tuple<RybColor, double>>(
Tuple.Create(m_colorPalette[0], DistanceFromLastPickedColor(m_colorPalette[0])),
(acc, color) =>
{
var currentDistance = DistanceFromLastPickedColor(color);
if (acc.Item2 < currentDistance)
return Tuple.Create(color, currentDistance);
else
return acc;
});
m_colorPalette.Remove(result.Item1);
var pick = result.Item1;
m_picked = new RybColor(
(m_pickedColorCount * m_picked.Red + pick.Red)
/ (m_pickedColorCount + 1),
(m_pickedColorCount * m_picked.Yellow + pick.Yellow)
/ (m_pickedColorCount + 1),
(m_pickedColorCount * m_picked.Blue + pick.Blue)
/ (m_pickedColorCount + 1));
m_pickedColorCount++;
System.Diagnostics.Debug.WriteLine("Farthest color is " + pick.ToString());
return pick;
}
private double DistanceFromLastPickedColor(RybColor color)
{
return RybColor.DistanceSquared(color, m_picked);
}
