Well

package window;

public class ColorLine {
public static int[] get(double a, double b, double t) {
    int[] color = new int[3];
    int where = (int)(1152.0*(t - a)/(b - a));
    if ((where >= 0)&&(where < 128))
    {
        color[0] = 128 - where;
        color[1] = 0;
        color[2] = 255;
    }
    else
        if ((where >= 128)&&(where < 384))
        {
            color[0] = 0;
            color[1] = where - 128;
            color[2] = 255;
        }
        else
            if ((where >= 384)&&(where < 640))
            {
                color[0] = 0;
                color[1] = 255;
                color[2] = 255-(where-384);
            }
            else
                if ((where >= 640)&&(where < 896))
                {
                    color[0] = where - 640;
                    color[1] = 255;
                    color[2] = 0;
                }
                else
                    if ((where >= 896)&&(where < 1152))
                    {
                        color[0] = 255;
                        color[1] = 255 - (where - 896);
                        color[2] = 0;
                    }
                    else
                        if (where >= 1152)
                        {
                            color[0] = 255;
                            color[1] = 0;
                            color[2] = 0;
                        }
                        else
                            if (where < 0)
                            {
                                color[0] = 128;
                                color[1] = 0;
                                color[2] = 255;
                            }

    return color;
}
}