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Binary search for point on path (https://stackoverflow.com/q/72764799/6509751)
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import 'dart:math'; | |
import 'dart:ui'; | |
void main() { | |
final path = Path(); | |
path.moveTo(0, 200); | |
path.lineTo(10, 210); | |
path.lineTo(30, 190); | |
path.lineTo(55, 150); | |
path.lineTo(80, 205); | |
path.lineTo(100, 0); | |
const searchDx = 75; | |
const iterations = 20; | |
final pathMetric = path.computeMetrics().first; | |
final pathDistance = pathMetric.length; | |
late Offset closestOffset; | |
var closestDistance = pathDistance / 2; | |
for (var n = 1; n <= iterations; n++) { | |
closestOffset = pathMetric.getTangentForOffset(closestDistance)!.position; | |
if (closestOffset.dx == searchDx) break; | |
final change = pathDistance / pow(2, n); | |
if (closestOffset.dx < searchDx) { | |
closestDistance += change; | |
} else { | |
closestDistance -= change; | |
} | |
} | |
print(closestOffset); | |
} |
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