48 lines
1.2 KiB
Dart
48 lines
1.2 KiB
Dart
import 'dart:math';
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import 'dart:ui';
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int highestPowerOf2(num x) => x < 1 ? 0 : pow(2, (log(x) / ln2).floor()).toInt();
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num smallestPowerOf2(num x, {bool allowNegativePower = false}) {
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return x < 1 && !allowNegativePower ? 1 : pow(2, (log(x) / ln2).ceil());
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}
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double roundToPrecision(final double value, {required final int decimals}) => (value * pow(10, decimals)).round() / pow(10, decimals);
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// cf https://en.wikipedia.org/wiki/Intersection_(geometry)#Two_line_segments
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Offset? segmentIntersection((Offset, Offset) s1, (Offset, Offset) s2) {
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final x1 = s1.$1.dx;
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final y1 = s1.$1.dy;
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final x2 = s1.$2.dx;
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final y2 = s1.$2.dy;
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final x3 = s2.$1.dx;
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final y3 = s2.$1.dy;
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final x4 = s2.$2.dx;
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final y4 = s2.$2.dy;
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final a1 = x2 - x1;
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final b1 = -(x4 - x3);
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final c1 = x3 - x1;
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final a2 = y2 - y1;
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final b2 = -(y4 - y3);
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final c2 = y3 - y1;
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final denom = a1 * b2 - a2 * b1;
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if (denom == 0) {
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// lines are parallel
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return null;
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}
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final s0 = (c1 * b2 - c2 * b1) / denom;
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final t0 = (a1 * c2 - a2 * c1) / denom;
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if (!(0 <= s0 && s0 <= 1 && 0 <= t0 && t0 <= 1)) {
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// segments do not intersect
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return null;
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}
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final x0 = x1 + s0 * (x2 - x1);
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final y0 = y1 + s0 * (y2 - y1);
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return Offset(x0, y0);
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}
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