Find the coordinates of a point along a quadratic Bezier curve in dart.

quadraticCurvePoint.dart

// credit: https://stackoverflow.com/a/9195706/10976714

// The formulas to calculate the coordinates of a point at any given position (from 0 to 1) on the Bezier curve are:
//  x(t) = (1-t)^2 * x1 + 2 * (1-t) * t * x2 + t^2 * x3
//  y(t) = (1-t)^2 * y1 + 2 * (1-t) * t * y2 + t^2 * y3
//  where (x1, y1) is the starting point, (x2, y2) is the control point and (x3, y3) is the end point.

// get a point along the Bezier curve line
// If you pass the start, end & control points, along with 0.5 for the halfway position, you get the offset to that point
Offset getQuadraticCurvePoint(Offset start, Offset control, Offset end, double position) {
  return Offset(
    _getQBezierValue(position, start.dx, control.dx, end.dx),
    _getQBezierValue(position, start.dy, control.dy, end.dy),
  );
}

double _getQBezierValue(double t, double p1, double p2, double p3) {
  final iT = 1 - t;
  return iT * iT * p1 + 2 * iT * t * p2 + t * t * p3;
}