#include "noise.hpp"

float mapfloat(float x, float in_min, float in_max, float out_min, float out_max)
{
  return (float)(x - in_min) * (out_max - out_min) / (float)(in_max - in_min) + out_min;
}


//using the algorithm from http://freespace.virgin.net/hugo.elias/models/m_perlin.html
// thanks to hugo elias
float Noise2(float x, float y)
{
  long noise;
  noise = x + y * 57;
  //noise = pow(noise << 13,noise);
  noise = (noise << 13)*noise;
  return ( 1.0 - ( long(noise * (noise * noise * 15731L + 789221L) + 1376312589L) & 0x7fffffff) / 1073741824.0);
}

float SmoothNoise2(float x, float y)
{
  float corners, sides, center;
  corners = ( Noise2(x-1, y-1)+Noise2(x+1, y-1)+Noise2(x-1, y+1)+Noise2(x+1, y+1) ) / 16;
  sides   = ( Noise2(x-1, y)  +Noise2(x+1, y)  +Noise2(x, y-1)  +Noise2(x, y+1) ) /  8;
  center  =  Noise2(x, y) / 4;
  return (corners + sides + center);
}

float InterpolatedNoise2(float x, float y)
{
  float v1,v2,v3,v4,i1,i2,fractionX,fractionY;
  long longX,longY;

  longX = long(x);
  fractionX = x - longX;

  longY = long(y);
  fractionY = y - longY;

  v1 = SmoothNoise2(longX, longY);
  v2 = SmoothNoise2(longX + 1, longY);
  v3 = SmoothNoise2(longX, longY + 1);
  v4 = SmoothNoise2(longX + 1, longY + 1);

  i1 = Interpolate(v1 , v2 , fractionX);
  i2 = Interpolate(v3 , v4 , fractionX);

  
  return(Interpolate(i1 , i2 , fractionY));
}

float Interpolate(float a, float b, float x)
{
  //cosine interpolations
  return(CosineInterpolate(a, b, x));
}

float LinearInterpolate(float a, float b, float x)
{
  return(a*(1-x) + b*x);
}

float CosineInterpolate(float a, float b, float x)
{
  float ft = x * 3.1415927;
  float f = (1 - cos(ft)) * .5;

  return(a*(1-f) + b*f);
}

float PerlinNoise2(float x, float y, float persistance, int octaves)
{
  float frequency, amplitude;
  float total = 0.0;

  for (int i = 0; i <= octaves - 1; i++)
  {
    frequency = pow(2,i);
    amplitude = pow(persistance,i);

    total = total + InterpolatedNoise2(x * frequency, y * frequency) * amplitude;
  }

  return(total);
}