discontinuedPackage jet_cad_floor_plan has been discontinued and replaced by jet_cad_2d_plan.

placementTransform function

Transform2 placementTransform({ required Vector2 at, required Vector2 basePoint, int? quarterTurns, (double, double)? rotation, bool mirrored = false, })

translation(at) · rotation · scale(mirrored ? -1 : 1, 1) · translation(-basePoint): the definition's base point lands on at (spec F-2), and a mirror flips the local x axis whatever the rotation.

The rotation is given one of two ways, never both (an ArgumentError, in release builds too):

• quarterTurns counter-clockwise, taken modulo 4 (negative allowed), with exact cosine and sine from a table (0 and ±1, never 6e-17);
• rotation, a unit vector (cos, sin) used exactly as given (spec 09c D5: a wall face's t).

Neither is no turn. The quarter-turn form is the rotation form at its table entry, so the two give the same bytes. No stored component is -0.0 in either form, so a placement stores clean numbers in a file.

Implementation

Transform2 placementTransform({
  required Vector2 at,
  required Vector2 basePoint,
  int? quarterTurns,
  (double, double)? rotation,
  bool mirrored = false,
}) {
  if (quarterTurns != null && rotation != null) {
    throw ArgumentError(
        'placementTransform takes quarterTurns or rotation, not both');
  }
  final (cos, sin) = rotation ?? _quarterTurn(quarterTurns ?? 0);
  final m = Transform2.translation(at.x, at.y)
      .multiply(Transform2(cos, sin, -sin, cos, 0, 0))
      .multiply(Transform2.scale(mirrored ? -1 : 1, 1))
      .multiply(Transform2.translation(-basePoint.x, -basePoint.y));
  double clean(double v) => v == 0 ? 0.0 : v;
  return Transform2(
      clean(m.a), clean(m.b), clean(m.c), clean(m.d), clean(m.e), clean(m.f));
}