// Mandelbrot/Julia Set Program
// Tom Dixon - Supercomp Period 3
//
// Left: Box zoom; Middle: Show iteration; Right: Default window
// Space Bar: Shows Julia set for current point, returns to Mandelbrot

#include<GL/glut.h>
#include<iostream.h>
#include<malloc.h>
#include<assert.h>

int xsize = 500, ysize = 500, mode = 0, ok=0;

double x1=-2.5, x2=1.5, y1=-2, y2=2, zx, zy, jx=0, jy=0, ***screen;

#include "mtga.h"

void init() {
  glClearColor(0,0,0,0);
  glShadeModel(GL_FLAT);
}

void display() {
  if (ok) {
    glBegin(GL_POINTS);
    for(int x=0; x<xsize; x++)
      for(int y=0; y<ysize; y++) {
        glColor3f(screen[x][y][0], screen[x][y][1], screen[x][y][2]);
        glVertex3f(x+0.5, y+0.5, 0);
      }
    glEnd();
  }
  else {
    free(screen);
    screen = (double ***)malloc(sizeof(double **)*xsize);
    for (int i = 0; i < xsize; i++)
      screen[i] = (double **)malloc(sizeof(double *)*ysize);
    for (i = 0; i < xsize; i++)
      for (int j = 0; j < ysize; j++)
        screen[i][j] = (double *)malloc(sizeof(double)*3);
    assert(screen);
    glClear(GL_COLOR_BUFFER_BIT);
    glLoadIdentity();
    glBegin(GL_POINTS);
    double a, b, ta, x ,y;
    int it, max=-1, min=10000, maxit=int(1/(x2-x1)+1/(y2-y1)+20);
    for(int i=0; i<xsize; i++)
      for(int j=0; j<ysize; j++) {
        x=x1+(x2-x1)*i/xsize;
        y=y2-(y2-y1)*j/ysize;
        it=0;
        a=x; b=y;
        while (it<maxit && a*a+b*b<4) {
          ta=a*a-b*b+(mode ? jx : x);
          b=2*a*b+(mode ? jy : y);
          a=ta;
          it++;
        }
        if (it>max) max=it;
        if (it<min) min=it;
      }
    maxit=max;
    for(int i=0; i<xsize; i++)
      for(int j=0; j<ysize; j++) {
        it=0;
        x=x1+(x2-x1)*i/xsize;
        y=y2-(y2-y1)*j/ysize;
        a=x; b=y;
        while (it<maxit && a*a+b*b<4) {
          ta=a*a-b*b+(mode ? jx : x);
          b=2*a*b+(mode ? jy : y);
          a=ta;
          it++;
        }
        if (it<maxit) {
          screen[i][j][0]=double(it-min)/(max-min);
          screen[i][j][1]=1-double(it-min)/(max-min);
          screen[i][j][2]=double(it-min)/(max-min);
        }
        else screen[i][j][0]=screen[i][j][1]=screen[i][j][2]=0;
        glColor3f(screen[i][j][0], screen[i][j][1], screen[i][j][2]);        
        glVertex3f(i+0.5, j+0.5, 0);
      }
    glEnd();
    ok=1;
  }
}

void reshape(int w, int h) {
  xsize=w; ysize=h;
  glViewport(0, 0, GLsizei(w), GLsizei(h));
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  glOrtho(0, xsize, 0, ysize, -1, 1);
  glMatrixMode(GL_MODELVIEW);
  ok=0;
}

void showit(int x, int y) {
  double a=x1+(x2-x1)*x/xsize, ia=a, b=y2-(y2-y1)*y/ysize, ib=b, ta;
  int it=0;
  glColor3f(1.0, 1.0, 1.0);
  glBegin(GL_LINE_STRIP);
  while (it<100 && a*a+b*b<4) {
    glVertex3f(a, b, 0);
    ta=a*a-b*b+ia;
    b=2*a*b+ib;
    a=ta;
    it++;
  }
  glVertex3f(a, b, 0);
  glEnd();
  ok=0;
}

void zoom(int button, int state, int x, int y) {
  if (button==GLUT_MIDDLE_BUTTON) showit(x, y);
  else if (button==GLUT_RIGHT_BUTTON) {
    x1=-2.5; x2=2; y1=-2; y2=2;
    reshape(xsize, ysize);
    glutPostRedisplay();
  }
  else if (button==GLUT_LEFT_BUTTON) {
    if (state==GLUT_DOWN) {
      zx=x1+(x2-x1)*x/xsize;
      zy=y2-(y2-y1)*y/ysize;
    }
    else {
      x2=x1+(x2-x1)*x/xsize;
      y1=y2-(y2-y1)*y/ysize;
      x1=zx; y2=zy;
      reshape(xsize, ysize);
      glutPostRedisplay();
    }
  }
}

void keyboard(unsigned char ch, int x, int y) {
  if (ch==' ') {
    mode=!mode;
    if (mode) {
      jx=x1+(x2-x1)*x/xsize;
      jy=y2-(y2-y1)*y/ysize;
    }
    x1=-2.5; x2=1.5; y1=-2; y2=2;
    reshape(xsize, ysize);
    glutPostRedisplay();
  }
  if (ch=='t' || ch=='T') writetga();
}

void main(int argc, char* argv[]) {
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
  glutInitWindowSize(xsize, ysize);
  glutInitWindowPosition(100, 100);
  glutCreateWindow("Mandelbrot/Julia-o-Rama");
  init();
  glutDisplayFunc(display);
  glutReshapeFunc(reshape);
  glutMouseFunc(zoom);
  glutKeyboardFunc(keyboard);
  glutMainLoop();
}