mandelbrot_original.cpp

/*
Modified from: http://rosettacode.org/wiki/Mandelbrot_set#PPM_non_interactive
c program:
--------------------------------
1. draws Mandelbrot set for Fc(z)=z*z +c
using Mandelbrot algorithm ( boolean escape time )
-------------------------------
2. technique of creating ppm file is  based on the code of Claudio Rocchini
http://en.wikipedia.org/wiki/Image:Color_complex_plot.jpg
create 24 bit color graphic file ,  portable pixmap file = PPM
see http://en.wikipedia.org/wiki/Portable_pixmap
to see the file use external application ( graphic viewer)
*/
#include <stdio.h>
#include <math.h>
#include <time.h>

int main()
{

	clock_t start, end;
	double cpu_time_used;

	/* screen ( integer) coordinate */
	int iX, iY;
	const int iXmax = 16384;
	const int iYmax = 16384;
	/* world ( double) coordinate = parameter plane*/
	double Cx, Cy;
	const double CxMin = -2.5;
	const double CxMax = 1.5;
	const double CyMin = -2.0;
	const double CyMax = 2.0;
	/* */
	double PixelWidth = (CxMax - CxMin) / iXmax;
	double PixelHeight = (CyMax - CyMin) / iYmax;
	/* color component ( R or G or B) is coded from 0 to 255 */
	/* it is 24 bit color RGB file */
	const int MaxColorComponentValue = 255;
	FILE * fp;
	char *filename = "mandelbrot.ppm";
	static unsigned char color[3];
	/* Z=Zx+Zy*i  ;   Z0 = 0 */
	double Zx, Zy;
	double Zx2, Zy2; /* Zx2=Zx*Zx;  Zy2=Zy*Zy  */
	/*  */
	int Iteration;
	const int IterationMax = 256;
	/* bail-out value , radius of circle ;  */
	const double EscapeRadius = 2;
	double ER2 = EscapeRadius*EscapeRadius;
	/*create new file,give it a name and open it in binary mode  */
	fp = fopen(filename, "wb"); /* b -  binary mode */
	/*write ASCII header to the file*/
	fprintf(fp, "P6\n %d\n %d\n %d\n", iXmax, iYmax, MaxColorComponentValue);
	/* compute and write image data bytes to the file*/
	start = clock();
	for (iY = 0; iY<iYmax; iY++)
	{
		Cy = CyMin + iY*PixelHeight;
		if (fabs(Cy)< PixelHeight / 2) Cy = 0.0; /* Main antenna */
		for (iX = 0; iX<iXmax; iX++)
		{
			Cx = CxMin + iX*PixelWidth;
			/* initial value of orbit = critical point Z= 0 */
			Zx = 0.0;
			Zy = 0.0;
			Zx2 = Zx*Zx;
			Zy2 = Zy*Zy;
			/* */
			for (Iteration = 0; Iteration<IterationMax && ((Zx2 + Zy2)<ER2); Iteration++)
			{
				Zy = 2 * Zx*Zy + Cy;
				Zx = Zx2 - Zy2 + Cx;
				Zx2 = Zx*Zx;
				Zy2 = Zy*Zy;
			};
			/* compute  pixel color (24 bit = 3 bytes) */
			if (Iteration == IterationMax)
			{ /*  interior of Mandelbrot set = black */
				color[0] = 0;
				color[1] = 0;
				color[2] = 0;
			}
			else
			{ /* exterior of Mandelbrot set = white */
				color[0] = ((IterationMax - Iteration) % 8) * 63;  /* Red */
				color[1] = ((IterationMax - Iteration) % 4) * 127;  /* Green */
				color[2] = ((IterationMax - Iteration) % 2) * 255;  /* Blue */
			};
			/*write color to the file*/
			fwrite(color, 1, 3, fp);
		}
	}
	end = clock();

	cpu_time_used = ((double)(end - start)) / CLOCKS_PER_SEC;
	printf("time = %f seconds\n", cpu_time_used);
	fclose(fp);
	int TESTE;
	scanf("%d", &TESTE);
	return 0;
}