#include <stdio.h>
#include <math.h>
#include "SDL/SDL.h"

#define WIDTH 900
#define HEIGHT 900
#define DEPTH 32

struct complex {
    double real;
    double img;
};

void setpixel(SDL_Surface *screen, int x, int y, int color)
{
    SDL_Rect rect = {x, y, 1, 1};
    SDL_FillRect(screen, &rect, color);
}

int mandelbrot(struct complex c, int itr) // returns the iterations performed
{
    struct complex z;
    z.real=0; z.img=0;
    int i;
    double absZ;

    for(i=0; i<=itr; i++) //set iterations
    {
        absZ=z.real;
        z.real=(z.real*z.real-z.img*z.img)+(c.real);
        z.img=(absZ*z.img)*2+c.img; // find z^2 + c


        absZ=z.real*z.real+z.img*z.img; // find abs(z)

        if( absZ>=4 )
            break; // outside circle with r=2
    }
    if(i>=itr-1)
        return 0;
    return i+1-log(log(sqrt(absZ*2000)))/log(2);
}


int main()
{
    SDL_Surface *screen;
    SDL_Event event;

    int quit=0;

    if( SDL_Init(SDL_INIT_VIDEO) < 0 )
        return 1;

    if(!(screen = SDL_SetVideoMode( WIDTH, HEIGHT, DEPTH, SDL_HWSURFACE)))
    {
        SDL_Quit();
        return 1;
    }
    int i,j,iter, itr=300;
    double yoff=-1.5, xoff=-2;
    double scale=(1/3.0);
    int draw=1;
    struct complex c;

    while(!quit)
    {
        while(SDL_PollEvent(&event))
        {
            if(event.type==SDL_QUIT)
                quit=1;
            switch(event.type)
            {
                case SDL_KEYDOWN:
                    switch(event.key.keysym.sym)
                    {
                        case SDLK_LEFT:
                            xoff-=.2/scale;
                            break;
                        case SDLK_RIGHT:
                            xoff+=.2/scale;
                            break;
                        case SDLK_UP:
                            yoff+=.2/scale;
                            break;
                        case SDLK_DOWN:
                            yoff-=.2/scale;
                            break;
                        case SDLK_SPACE:
                            draw=1;
                            printf("Drawing... ");
                            break;
                        case SDLK_1:
                            scale*=2;
                            printf("scale: %f\n", scale);
                            break;
                        case SDLK_2:
                            if(scale>.4)
                                scale/=2;
                            printf("scale: %f\n", scale);
                            break;
                        case SDLK_9:
                            itr+=1000;
                            printf("iterations: %d\n", itr);
                            break;
                        case SDLK_0:
                            if(itr>1000)
                                itr-=100;
                            printf("iterations: %d\n", itr);
                            break;
                        default:
                            break;
                    }
                    break;
                case SDL_MOUSEBUTTONDOWN:
                    if(event.button.button==SDL_BUTTON_LEFT){;
                        scale*=2;
                        xoff=xoff+(event.button.x)/(scale*WIDTH);
                        yoff=yoff+(event.button.y)/(scale*HEIGHT);
                        draw=1;
                    }
                    break;
                default:
                    break;

            }
        }
        if(draw){
            for(i=0; i<WIDTH; i++)
            {
                c.real=(double)(i/(scale*WIDTH))+xoff;
                for(j=0; j<HEIGHT; j++)
                {
                    c.img=(double)(j/(scale*HEIGHT))+yoff;
                    iter=mandelbrot(c, itr);
                    setpixel(screen, i, j, iter*0xF0FF);
                }
            }
            draw=0;
            printf("Done drawing!\n");
        }
        SDL_Flip(screen);
        SDL_Delay(30); // dont use 100% cpu!!!
    }

    SDL_Quit();

    return 0;
}