project-swan/src/perlin-test.cc

#include <swan/log.h>

#include <PerlinNoise/PerlinNoise.hpp>
#include <png++/png.hpp>

static int grassLevel(const siv::PerlinNoise &perlin, int x) {
	return (int)(perlin.noise(x / 50.0, 0) * 13);
}

static int stoneLevel(const siv::PerlinNoise &perlin, int x) {
	return (int)(perlin.noise(x / 50.0, 10) * 10) + 10;
}

int main() {
	siv::PerlinNoise perlin = siv::PerlinNoise(100);

	int x1 = -1600;
	int x2 = 1600;
	int y1 = -800;
	int y2 = 800;

	png::image<png::gray_pixel> image(x2 - x1 + 1, y2 - y1 + 1);
	Swan::info << "perlin-test.png: " << (x2 - x1 + 1) << "x" << (y2 - y1 + 1);

	for (int x = x1; x <= x2; ++x) {
		int px = x - x1;
		int grass_level = grassLevel(perlin, x);
		int stone_level = stoneLevel(perlin, x);

		for (int y = y1; y <= y2; ++y) {
			int py = y - y1;

			if (y > grass_level + 10) {
				double l = perlin.noise(x / 41.37, y / 16.37);
				if (l > 0.2)
					image[py][px] = 255;
				else
					image[py][px] = 0;
			} else if (y >= grass_level) {
				image[py][px] = 0;
			} else {
				image[py][px] = 255;
			}

			if (y == grass_level) {
				image[py][px] = 128;
			}
		}
	}

	image.write("perlin-test.png");
}