nandi/vflutter_ffi · mandelbrot_dart.dart

⑂ 59a731a766d2baec2d522605425d2fce9c6c7209

mandelbrot_dart.dart · 55 lines · 1.7 KBDart    Blame HistoryRaw
Add a Mandelbrot example app, and a V kernel worth demonstrating  nandithebull 1// A straight Dart transliteration of the V kernel in src/vflutter.v.
3// It exists purely so the example can render the *same* image both ways and
4// put a number on the difference. Keep it in sync with the V version — if the
5// two drift, the comparison stops being honest.
6import 'dart:math' as math;
7import 'dart:typed_data';
9import 'package:vflutter_ffi/vflutter_ffi.dart' as v;
11Uint8List renderDart(v.FractalView view) {
final out = Uint8List(view.width * view.height * 4);
final aspect = view.width / view.height;
final invW = 1.0 / view.width;
final invH = 1.0 / view.height;
final ln2 = math.log(2.0);
for (var y = 0; y < view.height; y++) {
  final im = view.centerY + (y * invH - 0.5) * view.scale;
  final row = y * view.width * 4;
  for (var x = 0; x < view.width; x++) {
    final re = view.centerX + (x * invW - 0.5) * view.scale * aspect;
    var zr = 0.0, zi = 0.0, zr2 = 0.0, zi2 = 0.0;
    var i = 0;
    while (i < view.maxIter) {
      zr2 = zr * zr;
      zi2 = zi * zi;
      if (zr2 + zi2 > 4.0) break;
      zi = 2.0 * zr * zi + im;
      zr = zr2 - zi2 + re;
      i++;
    final idx = row + x * 4;
    if (i >= view.maxIter) {
      out[idx + 3] = 255;
      continue;
    final mag = math.sqrt(zr2 + zi2);
    var nu = i.toDouble();
    if (mag > 1.0) {
      nu = i + 1.0 - math.log(math.log(mag) / ln2) / ln2;
    final t = nu / view.maxIter;
    out[idx] = (255.0 * (0.5 + 0.5 * math.sin(3.0 + t * 18.0))).toInt();
    out[idx + 1] = (255.0 * (0.5 + 0.5 * math.sin(3.6 + t * 18.0))).toInt();
    out[idx + 2] = (255.0 * (0.5 + 0.5 * math.sin(4.2 + t * 18.0))).toInt();
    out[idx + 3] = 255;
return out;

Add a Mandelbrot example app, and a V kernel worth demonstrating 81540bb nandithebull 21h ago	1	// A straight Dart transliteration of the V kernel in src/vflutter.v.
	2	//
	3	// It exists purely so the example can render the same image both ways and
	4	// put a number on the difference. Keep it in sync with the V version — if the
	5	// two drift, the comparison stops being honest.
	6	import 'dart:math' as math;
	7	import 'dart:typed_data';
	8
	9	import 'package:vflutter_ffi/vflutter_ffi.dart' as v;
	10
	11	Uint8List renderDart(v.FractalView view) {
	12	final out = Uint8List(view.width * view.height * 4);
	13	final aspect = view.width / view.height;
	14	final invW = 1.0 / view.width;
	15	final invH = 1.0 / view.height;
	16	final ln2 = math.log(2.0);
	17
	18	for (var y = 0; y < view.height; y++) {
	19	final im = view.centerY + (y * invH - 0.5) * view.scale;
	20	final row = y * view.width * 4;
	21	for (var x = 0; x < view.width; x++) {
	22	final re = view.centerX + (x * invW - 0.5) * view.scale * aspect;
	23
	24	var zr = 0.0, zi = 0.0, zr2 = 0.0, zi2 = 0.0;
	25	var i = 0;
	26	while (i < view.maxIter) {
	27	zr2 = zr * zr;
	28	zi2 = zi * zi;
	29	if (zr2 + zi2 > 4.0) break;
	30	zi = 2.0 * zr * zi + im;
	31	zr = zr2 - zi2 + re;
	32	i++;
	33	}
	34
	35	final idx = row + x * 4;
	36	if (i >= view.maxIter) {
	37	out[idx + 3] = 255;
	38	continue;
	39	}
	40
	41	final mag = math.sqrt(zr2 + zi2);
	42	var nu = i.toDouble();
	43	if (mag > 1.0) {
	44	nu = i + 1.0 - math.log(math.log(mag) / ln2) / ln2;
	45	}
	46	final t = nu / view.maxIter;
	47
	48	out[idx] = (255.0 * (0.5 + 0.5 * math.sin(3.0 + t * 18.0))).toInt();
	49	out[idx + 1] = (255.0 * (0.5 + 0.5 * math.sin(3.6 + t * 18.0))).toInt();
	50	out[idx + 2] = (255.0 * (0.5 + 0.5 * math.sin(4.2 + t * 18.0))).toInt();
	51	out[idx + 3] = 255;
	52	}
	53	}
	54	return out;
	55	}