/** Prepare ball images with different sizes */
private void makeBalls() {
balls = new Image[nBalls];
byte red[] = new byte[256];
byte green[] = new byte[256];
byte blue[] = new byte[256];
for (int id = 0; id < nBalls; id++) {
// smaller `b' means closer to black
// if id == 0 (fartherest from the viewer)
// b = 1/(1 + zContrast)
// the outer blend() gives a color close to bgGrey
// if id == nBalls - 1 (closest to the viewer),
// b = 1, the outer blend() gives the color of
// the inner blend()
double b = (zContrast * id / (nBalls - 1) + 1) / (zContrast + 1);
for (int i = maxr; i >= 0; --i) {
// closeness to the spotlight
double q = 1 - 1. * i / maxr;
// dampness of the color along the radius
double p = 1 - rContrast * i / maxr;
// contrast of the spotlight
// if i == 0 (closest to the spotlight),
// d = 1.0 - spotlightAmp, the inner
// blend() gives a color close to 255
// (if spotlightAmp == 1).
// if i == maxr (fartherest from the spotlight),
// d = 1.0, the inner blend() gives
// the foreground color, i.e., Rl, Gl, Bl
// Thus, the inner blend() depends on the distance
// from the spotlight, i == 0 means to be closest
// to the spotlight
double d = 1 - q * spotlightAmp;
red[i] = (byte) blend(blend(Rl * p, 255, d), 0, b);
green[i] = (byte) blend(blend(Gl * p, 255, d), 0, b);
blue[i] = (byte) blend(blend(Bl * p, 255, d), 0, b);
}
// 256 color model
IndexColorModel model = new IndexColorModel(8, maxr + 1, red, green, blue, 0);
balls[id] = component.createImage(new MemoryImageSource(R * 2, R * 2, model, data, 0, R * 2));
}
}
