/* Compute/draw mandelbrot set using MPI/MPE commands
 * Written Winter, 1998, W. David Laverell.
 * Simplified Winter 2002, Joel Adams. 
 */

#include <stdio.h>
#include <math.h>
#include <sys/time.h>
#include "mpi.h"
#include "mpe.h"
#include "display.h"


/* compute the mandelbrot-set function for a given
 *  point in the complex plane.
 * Receive: doubles x and y,
 *          complex c.
 * Modify: doubles ans_x and ans_y.
 * POST: ans_x and ans_y contain the results of the mandelbrot-set
 *        function for x, y, and c.
 */
void compute(double x, double y, double c_real, double c_imag,
        double *ans_x, double *ans_y)
{
        *ans_x = x*x - y*y + c_real;
        *ans_y = 2*x*y + c_imag;
}

/* compute the 'distance' between x and y.
 * Receive: doubles x and y.
 * Return: x^2 + y^2.
 */
double distance(double x, double y)
{
        return(x*x + y*y);
}


int main(int argc, char* argv[])
{
    const int  WINDOW_SIZE = 1024;

    int        n,
               ix,
               iy;
    double     spacing=.005,
               x,
               y,
               c_real,
               c_imag,
               x_center = 0.0,
               y_center = 0.0;
    MPE_XGraph graph;

    MPI_Init(&argc,&argv);

    printf("\nEnter spacing (.005): ");
    scanf("%lf",&spacing);
    printf("\nEnter coordinates of center point (0,0): ");
    scanf("%lf %lf", &x_center, &y_center);
    printf("\nSpacing=%lf, center=(%lf,%lf)\n",
            spacing, x_center, y_center);

    MPE_Open_graphics( &graph, MPI_COMM_WORLD, 
                         getDisplay(),
                         -1, -1,
                         WINDOW_SIZE, WINDOW_SIZE, 0 );

    for (ix = 0; ix < WINDOW_SIZE; ix++)
    {
       for (iy = 0; iy < WINDOW_SIZE; iy++)
       {
         c_real=(ix - 400) * spacing - x_center;
         c_imag=(iy - 400) * spacing - y_center;
         x = y = 0.0;
         n = 0;

         while (n < 50 && distance(x,y) < 4.0)
         {
            compute(x,y,c_real,c_imag,&x,&y);
            n++;
         }

        if (n < 50)
          MPE_Draw_point(graph,ix,iy,MPE_RED);
        else
          MPE_Draw_point(graph,ix,iy,MPE_BLACK);
       }
    }
    getchar();
    getchar();
    MPE_Close_graphics( &graph );

    MPI_Finalize();
    return 0;
}