DOS Borland-C++ old source code of mine

Mandel.c

//---------------------------------------------------------------
//	Mandel.c
//---------------------------------------------------------------
//	Fractal de Mandelbrot - Esau R.O
//---------------------------------------------------------------

#include "mandel.h"
#include "graficos.h"

extern double gf_x1;
extern double gf_y1;
extern double gf_x2;
extern double gf_y2;

extern int gn_max_x;
extern int gn_max_y;

extern int gn_pasos;

extern int gn_Estilo;


int Mandelbrot (int inicializar, int metodo)
{
	int		max_x,	max_y,
			k,		p,		q,
			pasos,	terminar,
			color = 1;

	double	paso_x, paso_y,
			pos_x,	pos_y,
			iter_x, iter_y,
			temp_x;

	char 	c;


	if (inicializar == TRUE)
	{
		gf_x1 = -2.5;
		gf_y1 = -1.2;
		gf_x2 = 0.7;
		gf_y2 = 1.2;
		gn_pasos = 256;
	}

	if (metodo == EX_M_INCREMENTAL)
	{
		cleardevice();
	}

	MarcarEnProgreso (TRUE);

	paso_x = (gf_x2 - gf_x1) / gn_max_x;
	paso_y = (gf_y2 - gf_y1) / gn_max_y;

	for ((metodo == EX_M_INCREMENTAL)?(q = 64):(q = gn_pasos); q <= gn_pasos; q += 64)
	{
		for (k = 0; k <= gn_max_x; k++)
		{
			for (p = 0; p <= gn_max_y; p++)
			{
				pos_x = gf_x1 + k * paso_x;
				pos_y = gf_y2 - p * paso_y;

				iter_x = 0.0;
				iter_y = 0.0;

				terminar = FALSE;
				pasos = 0;

				while (! terminar)
				{
					temp_x = (iter_x * iter_x) - (iter_y * iter_y) + pos_x;

					iter_y = 2 * (iter_x * iter_y) + pos_y;

					iter_x = temp_x;

					pasos++;

					if ((iter_x * iter_x + iter_y * iter_y) >= 4.0)
					{
						terminar = TRUE;
					}

					if (pasos >= q)
					{
						terminar = TRUE;
					}
				}

				if (pasos < q)
				{
					if (gn_Estilo == EX_E_CONTRASTE)
					{
						putpixel (k, p, (pasos - 1) % 15 + 1);
					}
					else
					{
						color = (pasos - 1) % 28 + 1;

						if (color > 15)
						{
							color = 30 - color;
						}

						putpixel (k, p, color);
					}
				}
				else
				{
					if (metodo == EX_M_DIRECTO)
					{
						putpixel (k, p, 0);
					}
				}
			}

			if (kbhit())
			{
				c = getch();

				//------------------------------------------
				// para poder detener con teclas de funcion
				if (c == 0)
				{
					getch();
				}

				MarcarEnProgreso (FALSE);

				return FALSE;
			}
		}
	}

	return TRUE;
}