PPM_Fractal.cpp

/*
Use these commands to render img.ppm:
w & h: 4000 4000
2 -.5 0 .3
1
*/

#include<stdio.h>
#include<stdlib.h>
#include<vector>

using namespace std;


struct Complex{ double x,y; };

struct Color{ unsigned char r,g,b; };


//e is ^ , t is * , p is +
//z^2 + c    (Mandelbrot set)
#define Ze2pC \
zt.x = z.x * z.x - z.y * z.y + c.x;\
zt.y = 2.0 * z.x * z.y + c.y;\
z = zt;


//Global settings

static unsigned int height = 1000, width = 1500;
static vector<Color> pixels;

//view x and y, zoom
static double vx = -.5, vy = 0, zoom = 1.0;

static double limit = 4.0; //2^2
static unsigned int maxIter = 200;

static Complex startPoint = Complex{0,0};



void SaveImage(){
	printf("Saving image...  ");

	FILE *fp = fopen("img.ppm", "wb");
	(void) fprintf(fp, "P6\n%u %u\n255\n", width, height);

	fwrite(&pixels[0], sizeof(vector<Color>::value_type), width*height, fp);

	fclose(fp);

	printf("  Saved\n");
}

void Render(){
	printf("Rendering...  ");

	Color white = Color{(unsigned char)255,(unsigned char)255,(unsigned char)255};
	Color black = Color{(unsigned char)0,(unsigned char)0,(unsigned char)0};

	for (int i = 0; i < (width*height); i++)
	{
		//Center & Scale pixels to view -1.0 to 1.0 for 1000x1000
		//get 2d index - offset to make centered, div by 2.0(turn -.5,.5 to -1,1)/1000.0(scale 1kx1k to -1,1) (500)
		double x = ((i % width) - (width / 2.0)) / 500.0;
		double y = ((i / width) - (height / 2.0)) / 500.0;

		//Move and zoom view
		x = x * zoom + vx;
		y = y * zoom + vy;

		Complex c = Complex {x, y};
		Complex z = startPoint;
		Complex zt = z; //z temp

		for (size_t j = 0; j < maxIter; j++)
		{
			Ze2pC
		}
		
		if((z.x*z.x+z.y*z.y) < limit){
			pixels[i] = white;
		}else{
			pixels[i] = black;
		}

	}

	printf("  Rendered\n");

	SaveImage();
}

bool ReadCmd(){

	int cmd = 0;

	printf("Enter a command (0 for help):\n");
	scanf("%d",&cmd);

	if(cmd == 0){
		printf("1 - render & save, 2 - set [vx vy zoom], 3 - set iterations [maxIter], 4 - set iteration start point, 5 - set [width height], 6 - quit\n");
	}else if(cmd == 1){
		Render();
	}else if(cmd == 2){
		scanf("%lf %lf %lf",&vx,&vy,&zoom);
	}else if(cmd == 3){
		scanf("%u",&maxIter);
	}else if(cmd == 4){
		scanf("%lf %lf",&startPoint.x,&startPoint.y);
	}else if(cmd == 5){
		scanf("%u %u",&width,&height);
		pixels.clear();
		pixels = vector<Color>(width * height);
	}else if(cmd == 6)
		return false;

	return true;
}


int main(int argc, char* argv[]) {
	int w,h;
	
	printf("width height: ");
	scanf("%u %u",&w,&h);

	width = w;
	height = h;
	pixels = vector<Color>(width * height);


	while(ReadCmd()){}

	return 0;
}