function drawAngleGradient(ctx, options){
    var delta = options.endAngle - options.startAngle;
    for(var angle = options.startAngle; angle < options.endAngle; angle += options.angleStep){
        var t = (angle - options.startAngle) / delta;
        drawLine(ctx, {
            start: options.center,
            end: [
                options.center[0] + options.radius * Math.cos(angle),
                options.center[1] + options.radius * Math.sin(angle)
            ],
            color: mixColors(options.startColor, options.endColor, t)
        });
    }
}