for (int y = 0; y < side; y++) {
for (int x = 0; x < side; x++) {
final int index = y * side + x;
final float h = (float) function.eval(x, y, 0);
heightData[index] = h;
int col = (int) (h * h * 255 * 0.6);
col = MathUtils.clamp(col, 0, 255);
colorData[index * 4 + 0] = (byte) (col * 1.0);