code:

#include <iostream>
#include <complex>
#include <vector>
#include <chrono>
#include <thread>
#include <SDL/SDL.h>
#include "sdl_helpers.h"
#include "mandelbrot_common.h"

struct thread_params
{
	std::vector<std::vector<int>> *set;
	int min_x;
	int max_x;
	int width;
	int height;
};

void mandelbrot_thread(thread_params *p)
{
	for (int i = p->min_x; i < p->max_x; i++) {
		std::vector<int> column(p->height);
		for (int j = 0; j < p->height; j++) {
			double x_norm = (double)i / p->width;
			double y_norm = (double)j / p->height;
			int iters = mandelbrot(std::complex<double>(x_norm, y_norm));
			column[j] = iters;
		}
		(*p->set)[i] = column;
	}
}

std::vector<std::vector<int>> mandelbrot_set(int width, int height)
{
	constexpr int num_threads = 1024;
	std::cout << "Number of threads: " << num_threads << "\n";

	auto set = new std::vector<std::vector<int>>(width);
	std::vector<std::thread*> threads;

	int slice = width / num_threads;
	for (int i = 0; i < num_threads; i++) {
		struct thread_params *p = new struct thread_params;
		p->set = set;
		p->min_x = slice * i;
		p->max_x = slice * (i + 1);
		p->width = width;
		p->height = height;

		std::thread *t = new std::thread(mandelbrot_thread, p);
		threads.push_back(t);
	}
	for (std::thread *t : threads) {
		t->join();
		delete t;
	}

	return *set;
}

int main(int argc, char **argv)
{
	std::chrono::system_clock clock;

	auto before = clock.now();
	auto set = mandelbrot_set(MAX_X, MAX_Y);
	auto after = clock.now();
	std::chrono::duration<double> diff = after - before;
	render_mandelbrot(set, diff.count());

	return 0;
}