color mappings

	static int hotColdMapping(double f){
		f*=Math.PI;
		if(f < Math.PI/2){
			float r = (float) Math.cos(f);
			float g = (float) (1-Math.sin(f));
			return Pixel.rgb_fromNormalized(r, g, 0);
		} else {
			float b = (float) -Math.cos(f);
			float g = (float) (1-Math.sin(f));
			return Pixel.rgb_fromNormalized(0, g, b);
		}
	}
	
	static int rgbMapping(double f, int color0, int color1, int ...colors){
		int[] c = new int[colors.length+2];
		c[0] = color0;
		c[1] = color1;
		System.arraycopy(colors, 0, c, 2, colors.length);
		//
		int idx = (int)(f*(c.length-1));
		double stepSize = 1.0/(c.length-1);
		f = (f-idx*stepSize)/stepSize;
		int c0 = c[idx];
		int c1 = c[Math.min(idx+1, c.length-1)];
		return Pixel.rgb_fromNormalized(
				interpolateLinear((float)f, Pixel.r_normalized(c0), Pixel.r_normalized(c1)),
				interpolateLinear((float)f, Pixel.g_normalized(c0), Pixel.g_normalized(c1)),
				interpolateLinear((float)f, Pixel.b_normalized(c0), Pixel.b_normalized(c1)));
	}
	
	static float interpolateLinear(float m, float v0, float v1){
		return Math.min(1, v0+m*(v1-v0));
	}