I wrote the two methods below to automatically select N distinct colors. It works by defining a piecewise linear function on the RGB cube. The benefit of this is you can also get a progressive scale if that's what you want, but when N gets large the colors can start to look similar. I can also imagine evenly subdividing the RGB cube into a lattice and then drawing points. Does anyone know any other methods? I'm ruling out defining a list and then just cycling through it. I should also say I don't generally care if they clash or don't look nice, they just have to be visually distinct.
public static List<Color> pick(int num) {
List<Color> colors = new ArrayList<Color>();
if (num < 2)
return colors;
float dx = 1.0f / (float) (num - 1);
for (int i = 0; i < num; i++) {
colors.add(get(i * dx));
}
return colors;
}
public static Color get(float x) {
float r = 0.0f;
float g = 0.0f;
float b = 1.0f;
if (x >= 0.0f && x < 0.2f) {
x = x / 0.2f;
r = 0.0f;
g = x;
b = 1.0f;
} else if (x >= 0.2f && x < 0.4f) {
x = (x - 0.2f) / 0.2f;
r = 0.0f;
g = 1.0f;
b = 1.0f - x;
} else if (x >= 0.4f && x < 0.6f) {
x = (x - 0.4f) / 0.2f;
r = x;
g = 1.0f;
b = 0.0f;
} else if (x >= 0.6f && x < 0.8f) {
x = (x - 0.6f) / 0.2f;
r = 1.0f;
g = 1.0f - x;
b = 0.0f;
} else if (x >= 0.8f && x <= 1.0f) {
x = (x - 0.8f) / 0.2f;
r = 1.0f;
g = 0.0f;
b = x;
}
return new Color(r, g, b);
}
