public void setOxygen( int n ) {
			oxygen = n;
			if ( oxygen == 100 ) {
				bgColor = maxColor;
			} else if ( oxygen == 0 ) {
				bgColor = minColor;
			} else {
				double p = oxygen / 100.0;
				int maxRed = maxColor.getRed();
				int maxGreen = maxColor.getGreen();
				int maxBlue = maxColor.getBlue();
				int minRed = minColor.getRed();
				int minGreen = minColor.getGreen();
				int minBlue = minColor.getBlue();
				bgColor = new Color( (int)(minRed+p*(maxRed-minRed)), (int)(minGreen+p*(maxGreen-minGreen)), (int)(minBlue+p*(maxBlue-minBlue)) );
			}
		}