43 lines
989 B
Dart
43 lines
989 B
Dart
part of sprites;
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abstract class Constraint {
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void preUpdate(Node node, double dt) {
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}
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void constrain(Node node, double dt);
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}
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double _dampenRotation(double src, double dst, double dampening) {
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double delta = dst - src;
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while (delta > 180.0) delta -= 360;
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while (delta < -180) delta += 360;
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delta *= dampening;
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return src + delta;
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}
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class ConstraintRotationToMovement {
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ConstraintRotationToMovement([this.dampening]);
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final double dampening;
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Point _lastPosition;
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void preUpdate(Node node, double dt) {
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_lastPosition = node.position;
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}
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void constrain(Node node, double dt) {
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assert(_lastPosition != null);
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if (_lastPosition == node.position) return;
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// Get the target angle
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Offset offset = node.position - _lastPosition;
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double target = degrees(GameMath.atan2(offset.dy, offset.dx));
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if (dampening == null)
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node.rotation = target;
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else
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node.rotation = _dampenRotation(node.rotation, target, dampening);
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}
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}
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