#include <stdio.h>
#include "bmpfile.h"

/*Mandelbrot values*/
#define RESOLUTION 8700.0
#define XCENTER -0.55
#define YCENTER 0.6
#define MAX_ITER 1000
#define WIDTH 1920.0
#define HEIGHT 1080.0

/*Colour Values*/
#define COLOUR_DEPTH 255
#define COLOUR_MAX 240.0
#define GRADIENT_COLOUR_MAX 230.0

#define FILENAME "my_mandelbrot_fractal.bmp"

 /** 
   * Computes the color gradiant
   * color: the output vector 
   * x: the gradiant (beetween 0 and 360)
   * min and max: variation of the RGB channels (Move3D 0 -> 1)
   * Check wiki for more details on the colour science: en.wikipedia.org/wiki/HSL_and_HSV 
   */
void GroundColorMix(double* color, double x, double min, double max)
{
  /*
   * Red = 0
   * Green = 1
   * Blue = 2
   */
    double posSlope = (max-min)/60;
    double negSlope = (min-max)/60;

    if( x < 60 )
    {
        color[0] = max;
        color[1] = posSlope*x+min;
        color[2] = min;
        return;
    }
    else if ( x < 120 )
    {
        color[0] = negSlope*x+2.0*max+min;
        color[1] = max;
        color[2] = min;
        return;
    }
    else if ( x < 180  )
    {
        color[0] = min;
        color[1] = max;
        color[2] = posSlope*x-2.0*max+min;
        return;
    }
    else if ( x < 240  )
    {
        color[0] = min;
        color[1] = negSlope*x+4.0*max+min;
        color[2] = max;
        return;
    }
    else if ( x < 300  )
    {
        color[0] = posSlope*x-4.0*max+min;
        color[1] = min;
        color[2] = max;
        return;
    }
    else
    {
        color[0] = max;
        color[1] = min;
        color[2] = negSlope*x+6*max;
        return;
    }
}

/* Mandelbrot Set Image Demonstration  
 *
 * This is a simple single-process/single thread implementation
 * that computes a mandelbrot set and produces a corresponding
 * Bitmap image. The program demonstrates the use of a colour
 * gradient
 * 
 * This program uses the algorithm outlined in:
 *   "Building Parallel Programs: SMPs, Clusters And Java", Alan Kaminsky
 * 
 * This program requires libbmp for all bitmap operations. 
 *
 */

int main(int argc, char **argv)
{
  bmpfile_t *bmp;
  rgb_pixel_t pixel = {0, 0, 0, 0};
  int xoffset = -(WIDTH - 1) /2;
  int yoffset = (HEIGHT -1) / 2;
  bmp = bmp_create(WIDTH, HEIGHT, 32);
  int col = 0;
  int row = 0; 
  for(col = 0; col < WIDTH; col++){
     for(row = 0; row < HEIGHT; row++){
        
        //Determine where in the mandelbrot set, the pixel is referencing
        double x = XCENTER + (xoffset + col) / RESOLUTION;
        double y = YCENTER + (yoffset - row) / RESOLUTION;

        //Mandelbrot stuff

        double a = 0;
        double b = 0;
        double aold = 0;
        double bold = 0;
        double zmagsqr = 0;
        int iter =0;
	double x_col;
        double color[3];
        //Check if the x,y coord are part of the mendelbrot set - refer to the algorithm
        while(iter < MAX_ITER && zmagsqr <= 4.0){
           ++iter;
	   a = (aold * aold) - (bold * bold) + x;
           b = 2.0 * aold*bold + y;

           zmagsqr = a*a + b*b;

           aold = a;
           bold = b;	

        }
        
        /* Generate the colour of the pixel from the iter value */
        /* You can mess around with the colour settings to use different gradients */
        /* Colour currently maps from royal blue to red */ 
        x_col =  (COLOUR_MAX - (( ((float) iter / ((float) MAX_ITER) * GRADIENT_COLOUR_MAX))));
        GroundColorMix(color, x_col, 1, COLOUR_DEPTH);
        pixel.red = color[0];
        pixel.green = color[1];
	pixel.blue = color[2];
        bmp_set_pixel(bmp, col, row, pixel);

     }


  }


  bmp_save(bmp, FILENAME);
  bmp_destroy(bmp);

  return 0;
}