anime.d

import std.stdio;
import std.complex : complex, Complex, abs, arg;
import std.algorithm.comparison : clamp;
import std.format : format;
import conv = std.conv;
import math = std.math;
import IF = imageformats;

alias Image = IF.IFImage;

immutable int size = 128; // 画像サイズ
real cx = 0; // 描画域の中心X座標
immutable real cy = 0; // 描画域の中心Y座標
immutable real zoom = 1; // -2 <= Im(z),Re(z) <= 2 からどれだけズームしたか？
immutable real scale = 4.0 / size / zoom; // 1 ピクセルは座標平面においていくつか？

immutable real PI = 3.1415926535897932384626;

// immutable int max_iter = conv.to!int(math.sqrt(2.0 * math.sqrt(math.abs(1 - math.sqrt(5 * zoom)))) * 66.5);
immutable int max_iter = 64;

Complex!real exp (Complex!real z) {
	return math.exp(z.re) * complex!real(math.cos(z.im), math.sin(z.im));
}

Complex!real cos (Complex!real z) {
	return (exp(
		complex!real(-z.im, z.re)
	) + exp(
		complex!real(z.im, -z.re)
	)) / 2.0;
}

int mand (Complex!real z, Complex!real c, int n) {
	if (n >= max_iter) {
		return max_iter;
	}
	z = ((7.0 * z + 2.0) - exp(complex!real(-z.im, z.re) * PI) * (5.0 * z + 2.0)) / 4.0;
	// z = ((7.0 * z + 2.0) - cos(z * PI) * (5.0 * z + 2.0)) / 4.0;
	if (abs(z) >= 1000.0) {
		return n;
	}
	if (abs(z) == 0.0) {
		return 999;
	}
	return mand(z, c, n + 1);
}

void main () {
	auto logmax = math.log(max_iter);
	for (int i = 0; i < 100; i++) {
		ubyte[] pixels;
		pixels.length = size * size;
		for (int y = 0; y < size; y++) {
			real ry = (y - size / 2) * scale + cy;
			for (int x = 0; x < size; x++) {
				real rx = (x - size / 2) * scale + cx;
				// Complex!real z = complex!real(0, 0);
				Complex!real c = complex!real(rx, -ry);
				int n = mand(c, c, 0);
				if (n < max_iter) {
					auto v = conv.to!ubyte(clamp(math.log(n) * 0xFF / logmax, 0, 0xFF));
					pixels[y * size + x] = v;
				}
			}
		}
		IF.write_image(format("out/%03d.png", i), size, size, pixels, IF.ColFmt.Y);
		writeln(format("out/%03d.png", i));
		cx += 0.1;
	}
}