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perf: expose
isPointInPolygon and make 40% faster (at least in JIT …
…mode) (#1907) Co-authored-by: Sebastian <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,76 @@ | ||
| import 'dart:async'; | ||
| import 'dart:math' as math; | ||
| import 'dart:ui'; | ||
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| import 'package:flutter_map/src/misc/point_in_polygon.dart'; | ||
| import 'package:logger/logger.dart'; | ||
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| class NoFilter extends LogFilter { | ||
| @override | ||
| bool shouldLog(LogEvent event) => true; | ||
| } | ||
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| typedef Result = ({ | ||
| String name, | ||
| Duration duration, | ||
| }); | ||
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| Future<Result> timedRun(String name, dynamic Function() body) async { | ||
| Logger().i('running $name...'); | ||
| final watch = Stopwatch()..start(); | ||
| await body(); | ||
| watch.stop(); | ||
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| return (name: name, duration: watch.elapsed); | ||
| } | ||
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| List<Offset> makeCircle(int points, double radius, double phase) { | ||
| final slice = math.pi * 2 / (points - 1); | ||
| return List.generate(points, (i) { | ||
| // Note the modulo is only there to deal with floating point imprecision | ||
| // and ensure first == last. | ||
| final angle = slice * (i % (points - 1)) + phase; | ||
| return Offset(radius * math.cos(angle), radius * math.sin(angle)); | ||
| }, growable: false); | ||
| } | ||
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| // NOTE: to have a more prod like comparison, run with: | ||
| // $ dart compile exe benchmark/crs.dart && ./benchmark/crs.exe | ||
| // | ||
| // If you run in JIT mode, the resulting execution times will be a lot more similar. | ||
| Future<void> main() async { | ||
| Logger.level = Level.all; | ||
| Logger.defaultFilter = NoFilter.new; | ||
| Logger.defaultPrinter = SimplePrinter.new; | ||
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| final results = <Result>[]; | ||
| const N = 3000000; | ||
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| final circle = makeCircle(1000, 1, 0); | ||
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| results.add(await timedRun('In circle', () { | ||
| const point = math.Point(0, 0); | ||
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| bool yesPlease = true; | ||
| for (int i = 0; i < N; ++i) { | ||
| yesPlease = yesPlease && isPointInPolygon(point, circle); | ||
| } | ||
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| assert(yesPlease, 'should be in circle'); | ||
| return yesPlease; | ||
| })); | ||
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| results.add(await timedRun('Not in circle', () { | ||
| const point = math.Point(4, 4); | ||
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| bool noSir = false; | ||
| for (int i = 0; i < N; ++i) { | ||
| noSir = noSir || isPointInPolygon(point, circle); | ||
| } | ||
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| assert(!noSir, 'should not be in circle'); | ||
| return noSir; | ||
| })); | ||
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| Logger().i('Results:\n${results.map((r) => r.toString()).join('\n')}'); | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,29 @@ | ||
| import 'dart:math' as math; | ||
| import 'dart:ui'; | ||
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| /// Checks whether point [p] is within the specified closed [polygon] | ||
| /// | ||
| /// Uses the even-odd algorithm and requires closed loop polygons, i.e. | ||
| /// `polygon.first == polygon.last`. | ||
| bool isPointInPolygon(math.Point p, List<Offset> polygon) { | ||
| final len = polygon.length; | ||
| assert(len >= 3, 'not a polygon'); | ||
| assert(polygon.first == polygon.last, 'polygon not closed'); | ||
| final double px = p.x.toDouble(); | ||
| final double py = p.y.toDouble(); | ||
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| bool isInPolygon = false; | ||
| for (int i = 0, j = len - 1; i < len; j = i++) { | ||
| final double poIx = polygon[i].dx; | ||
| final double poIy = polygon[i].dy; | ||
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| final double poJx = polygon[j].dx; | ||
| final double poJy = polygon[j].dy; | ||
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| if ((((poIy <= py) && (py < poJy)) || ((poJy <= py) && (py < poIy))) && | ||
| (px < (poJx - poIx) * (py - poIy) / (poJy - poIy) + poIx)) { | ||
| isInPolygon = !isInPolygon; | ||
| } | ||
| } | ||
| return isInPolygon; | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,41 @@ | ||
| import 'dart:math' as math; | ||
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| import 'package:flutter_map/src/misc/point_in_polygon.dart'; | ||
| import 'package:flutter_test/flutter_test.dart'; | ||
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| List<Offset> makeCircle(int points, double radius, double phase) { | ||
| final slice = math.pi * 2 / (points - 1); | ||
| return List.generate(points, (i) { | ||
| // Note the modulo is only there to deal with floating point imprecision | ||
| // and ensure first == last. | ||
| final angle = slice * (i % (points - 1)) + phase; | ||
| return Offset(radius * math.cos(angle), radius * math.sin(angle)); | ||
| }, growable: false); | ||
| } | ||
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| void main() { | ||
| test('Smoke test for points in and out of polygons', () { | ||
| final circle = makeCircle(100, 1, 0); | ||
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| // Inside points | ||
| for (final point in makeCircle(32, 0.8, 0.0001)) { | ||
| final p = math.Point(point.dx, point.dy); | ||
| expect(isPointInPolygon(p, circle), isTrue); | ||
| } | ||
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| // Edge-case: check origin | ||
| expect(isPointInPolygon(const math.Point(0, 0), circle), isTrue); | ||
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| // Outside points: small radius | ||
| for (final point in makeCircle(32, 1.1, 0.0001)) { | ||
| final p = math.Point(point.dx, point.dy); | ||
| expect(isPointInPolygon(p, circle), isFalse); | ||
| } | ||
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| // Outside points: large radius | ||
| for (final point in makeCircle(32, 100000, 0.0001)) { | ||
| final p = math.Point(point.dx, point.dy); | ||
| expect(isPointInPolygon(p, circle), isFalse); | ||
| } | ||
| }); | ||
| } |