using System;

namespace AForge.Math;

public class PerlinNoise
{
	private double initFrequency = 1.0;

	private double initAmplitude = 1.0;

	private double persistence = 0.65;

	private int octaves = 4;

	public double InitFrequency
	{
		get
		{
			return initFrequency;
		}
		set
		{
			initFrequency = value;
		}
	}

	public double InitAmplitude
	{
		get
		{
			return initAmplitude;
		}
		set
		{
			initAmplitude = value;
		}
	}

	public double Persistence
	{
		get
		{
			return persistence;
		}
		set
		{
			persistence = value;
		}
	}

	public int Octaves
	{
		get
		{
			return octaves;
		}
		set
		{
			octaves = System.Math.Max(1, System.Math.Min(32, value));
		}
	}

	public PerlinNoise()
	{
	}

	public PerlinNoise(int octaves, double persistence)
	{
		this.octaves = octaves;
		this.persistence = persistence;
	}

	public PerlinNoise(int octaves, double persistence, double initFrequency, double initAmplitude)
	{
		this.octaves = octaves;
		this.persistence = persistence;
		this.initFrequency = initFrequency;
		this.initAmplitude = initAmplitude;
	}

	public double Function(double x)
	{
		double num = initFrequency;
		double num2 = initAmplitude;
		double num3 = 0.0;
		for (int i = 0; i < octaves; i++)
		{
			num3 += SmoothedNoise(x * num) * num2;
			num *= 2.0;
			num2 *= persistence;
		}
		return num3;
	}

	public double Function2D(double x, double y)
	{
		double num = initFrequency;
		double num2 = initAmplitude;
		double num3 = 0.0;
		for (int i = 0; i < octaves; i++)
		{
			num3 += SmoothedNoise(x * num, y * num) * num2;
			num *= 2.0;
			num2 *= persistence;
		}
		return num3;
	}

	private double Noise(int x)
	{
		int num = (x << 13) ^ x;
		return 1.0 - (double)((num * (num * num * 15731 + 789221) + 1376312589) & 0x7FFFFFFF) / 1073741824.0;
	}

	private double Noise(int x, int y)
	{
		int num = x + y * 57;
		num = (num << 13) ^ num;
		return 1.0 - (double)((num * (num * num * 15731 + 789221) + 1376312589) & 0x7FFFFFFF) / 1073741824.0;
	}

	private double SmoothedNoise(double x)
	{
		int num = (int)x;
		double a = x - (double)num;
		return CosineInterpolate(Noise(num), Noise(num + 1), a);
	}

	private double SmoothedNoise(double x, double y)
	{
		int num = (int)x;
		int num2 = (int)y;
		double a = x - (double)num;
		double a2 = y - (double)num2;
		double x2 = Noise(num, num2);
		double x3 = Noise(num + 1, num2);
		double x4 = Noise(num, num2 + 1);
		double x5 = Noise(num + 1, num2 + 1);
		double x6 = CosineInterpolate(x2, x3, a);
		double x7 = CosineInterpolate(x4, x5, a);
		return CosineInterpolate(x6, x7, a2);
	}

	private double CosineInterpolate(double x1, double x2, double a)
	{
		double num = (1.0 - System.Math.Cos(a * System.Math.PI)) * 0.5;
		return x1 * (1.0 - num) + x2 * num;
	}
}