/* Sequential Mandelbrot program */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <GL/glut.h>

#define		X_RESN	800       /* x resolution */
#define		Y_RESN	600       /* y resolution */

typedef struct complextype
	{
        float real, imag;
	} Compl;

void init() {

	// Clear the window
 /* select clearing (background) color   */
   glClearColor(0.5, 0.5, 0.5, 0.0);     // These RGB values make gray
   
/* initialize viewing values */
   glMatrixMode(GL_PROJECTION);			// Select Matrix Mode
   glLoadIdentity();				// Provide Base Matrix 
   glOrtho(-50.0, 1000.0, -50.0, 500.0, -1.0, 1.0);   	// Set window dimensions
   // Parameters:  glOrtho(Left, Right, Bottom, Top, Front, Back)
}

void reshape(int width, int height) {

	// Set the new viewport size
	glViewport(0, 0, (GLint)width, (GLint)height);

	// Clear the window
	glClear(GL_COLOR_BUFFER_BIT);
}

void draw(void) {
        int k;
	float i,j;
        Compl	z, c;
        float	lengthsq, temp;
	float max=0.0,min=4.0, maxK=0.0;
	glClear(GL_COLOR_BUFFER_BIT);

	// Set the drawing color
	glColor3f(1.0, 1.0, 1.0);

        /* Calculate and draw points */

        for(i=0; i < X_RESN; i+=0.5) 
	     for(j=0; j < Y_RESN; j+=0.5) {

	          z.real = z.imag = 0.0;
 	      	  c.real = ((float) j - 400.0)/200.0; 
		  /* scale factors for 800 x 600 window */
		  c.imag = ((float) i - 400.0)/200.0;
        	  k = 0;
  	      do  {                       /* iterate for pixel color */

	        temp = z.real*z.real - z.imag*z.imag + c.real;
     		z.imag = 2.0*z.real*z.imag + c.imag;
            	z.real = temp;
	 	lengthsq = z.real*z.real+z.imag*z.imag;
	        k++;

          	} while (lengthsq < 4.0 && k < 100);
		if (k==100) {
			if (lengthsq > max) max = lengthsq;
			if (lengthsq < min) min = lengthsq;
			glColor3f(0.5,0.0,0.5);
			glBegin(GL_POINTS);
			glVertex3f((float)j, (float)i-100,0.0);
			glEnd();
		} else {
			if (k > maxK) maxK = k;
			glColor3f(k/99.0,0.0,0.0);
			glBegin(GL_POINTS);
			glVertex3f((float)j, (float)i-100,0.0);
			glEnd();
		}
    	 }
 // Flush the buffer to force drawing of all objects thus far
	glFlush();
	printf("MaxK=%f\n", maxK);
}

int main(int argc, char **argv) {

     /* Mandlebrot variables */

        int i, j, k;
        float	lengthsq, temp;


	// Open a window, name it "Hello World"
	glutInit(&argc, argv);  
	glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
	glutInitWindowSize(X_RESN, Y_RESN); 
	glutInitWindowPosition(10,10); 
	glutCreateWindow("Mandelbrot Set");	

	// Set the clear color to black
	glClearColor(0.0, 0.0, 0.0, 0.0);

	// Call an initialization function
	init();

	// Assign reshape() to be the function called whenever 
	// a reshape event occurs
	glutReshapeFunc(reshape);

	// Assign draw() to be the function called whenever a display
	// event occurs, generally after a resize or expose event
	glutDisplayFunc(draw);

	// Pass program control to tk's event handling code
	// In other words, loop forever
	glutMainLoop();

	return 0;
}