res/draw.js
function createCubehelix (steps, opts) {
	var data = [];

	for (var i = 0; i < steps; i++ ){
		data.push(cubehelix.rgb(i/steps, opts).map((v) => v/255));
	}

	return data;
}
function createCubehelix (steps, opts) {
	var data = [];

	for (var i = 0; i < steps; i++ ){
		data.push(cubehelix.rgb(i/steps, opts).map((v) => v/255));
	}

	return data;
}
create colormap by rotating cubehelix