mandelbrot.cpp

#include <stdint.h>
#include <complex>

#include <CL/sycl.hpp>

#include <png++/png.hpp>

namespace sycl = cl::sycl;

class GenerateFractal;

constexpr size_t width = 1280, height = 960;
constexpr size_t max_iterations = 16;

// Change these to get a different window
constexpr float min_x = -2, max_x = 1,
		min_y = -9.0 / 8, max_y = 9.0 / 8;

constexpr const uint8_t mandelbrot_colors[][3] = {
	{0x0A, 0x2F, 0x51},
	{0x0C, 0x3D, 0x5B},
	{0x0E, 0x4D, 0x64},
	{0x10, 0x5E, 0x6E},
	{0x13, 0x71, 0x77},
	{0x15, 0x80, 0x7B},
	{0x18, 0x89, 0x77},
	{0x1A, 0x91, 0x72},
	{0x1D, 0x9A, 0x6C},
	{0x32, 0xA6, 0x6B},
	{0x48, 0xB1, 0x6D},
	{0x5E, 0xBC, 0x72},
	{0x74, 0xC6, 0x7A},
	{0x8F, 0xD0, 0x8A},
	{0xAD, 0xDA, 0xA1},
	{0xC7, 0xE4, 0xB8},
	{0xDE, 0xED, 0xCF},
};

size_t escape_time(std::complex<float> c) {
	std::complex<float> z = 0;
	for (size_t i = 0; i < max_iterations; ++i) {
		z = z * z + c;
		if (std::abs(z) > 2) return i;
	}
	return max_iterations;
}

float mix(float x, float y, float a) {
	return x + a * (y - x); // Good enough for our purposes
}

std::complex<float> get_coordinates(size_t pixel_x, size_t pixel_y) {
	return std::complex{
		mix(min_x, max_x, ((float) pixel_x) / width),
		mix(max_y, min_y, ((float) pixel_y) / height)};
}

int main() {
	sycl::queue q;
	sycl::buffer<uint8_t, 2> image{{height, width}};

	q.submit([&](sycl::handler& cgh) {
		auto I = image.get_access<sycl::access::mode::write>(cgh);
		cgh.parallel_for<GenerateFractal>(sycl::range<2>{height, width}, [=](sycl::id<2> index) {
			I[index] = (uint8_t) escape_time(get_coordinates(index[1], index[0]));
		});
	});
	
	auto I = image.get_access<sycl::access::mode::read>();

	png::image<png::rgb_pixel> png_image(width, height);
	for (png::uint_32 y = 0; y < height; ++y) {
		for (png::uint_32 x = 0; x < height; ++x) {
			uint8_t idx = I[y][x];
			const uint8_t* col = mandelbrot_colors[idx];
			png_image[y][x] = png::rgb_pixel(col[0], col[1], col[2]);
		}
	}

	png_image.write("mandelbrot.png");

	return 0;
}