Fan2Variation.cs

using System;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Model;
 
namespace Waher.Script.Fractals.IFS.Variations.Flame
{
    public class Fan2Variation : FlameVariationMultipleParameters
    {
        private readonly double x;
        private readonly double y;
 
        public Fan2Variation(ScriptNode x, ScriptNode y, int Start, int Length, Expression Expression)
            : base(new ScriptNode[] { x, y }, new ArgumentType[] { ArgumentType.Scalar, ArgumentType.Scalar },
                  Start, Length, Expression)
        {
            this.x = 0;
            this.y = 0;
        }
 
        private Fan2Variation(double X, double Y, ScriptNode x, ScriptNode y, int Start, int Length,
            Expression Expression)
            : base(new ScriptNode[] { x, y }, new ArgumentType[] { ArgumentType.Scalar, ArgumentType.Scalar },
                  Start, Length, Expression)
        {
            this.x = X;
            this.y = Y;
        }
 
        public override string[] DefaultArgumentNames
        {
            get
            {
                return new string[] { "x", "y" };
            }
        }
 
        public override IElement Evaluate(IElement[] Arguments, Variables Variables)
        {
            double X = Expression.ToDouble(Arguments[0].AssociatedObjectValue);
            double Y = Expression.ToDouble(Arguments[1].AssociatedObjectValue);
 
            return new Fan2Variation(X, Y, this.Arguments[0], this.Arguments[1], this.Start, this.Length, this.Expression);
        }
 
        public override void Operate(ref double x, ref double y)
        {
            double r = Math.Sqrt(x * x + y * y);
            double a = Math.Atan2(x, y);
            double p1 = Math.PI * this.x * this.x / 2 + 1e-6;
            double t = a + this.y - 2 * p1 * Math.Floor(a * this.y / p1);
            
            if (t > p1)
                a -= p1;
            else
                a += p1;
 
            x = r * Math.Sin(a);
            y = r * Math.Cos(a);
        }
 
        public override string FunctionName => nameof(Fan2Variation);
    }
}