/// <summary>
/// Returns the position of the nearest vertex.
/// </summary>
/// <returns>
/// Grid position of the nearest vertex.
/// </returns>
///
/// <param name="grid">
/// The rectangular grid instance.
/// </param>
/// <param name="point">
/// Point in world space.
/// </param>
/// <param name="system">
/// Coordinate system to use.
/// </param>
///
/// <remarks>
/// Returns the position of the nearest vertex from a given point in
/// either grid- or world space.
/// </remarks>
public static Vector3 NearestVertex(this RectGrid grid, Vector3 point, CSystem system)
{
var gridPoint = grid.WorldToGrid(point);
var roundedPoint = RoundVector3(gridPoint);
return(system == CSystem.Grid ? roundedPoint : grid.GridToWorld(roundedPoint));
}
/// <summary>
/// Returns the grid position of the nearest box.
/// </summary>
/// <returns>
/// Grid position of the nearest box.
/// </returns>
/// <param name="grid">
/// The rectangular grid instance.
/// </param>
/// <param name="point">
/// Point in world space.
/// </param>
/// <param name="system">
/// Coordinate system to use.
/// </param>
/// <remarks>
/// <para>
/// returns the coordinates of a cell in the grid. Since cell lies
/// between vertices all three values will always have +0.5
/// compared to vertex coordinates.
/// </para>
/// </remarks>
/// <example>
/// <code>
/// GFRectGrid myGrid;
/// Vector3 worldPoint;
/// // something like (2.5, -1.5, 3.5)
/// Vector3 box = myGrid.NearestBoxG(worldPoint);
/// </code>
/// </example>
public static Vector3 NearestCell(this RectGrid grid, Vector3 point, CSystem system)
{
var shift = .5f * Vector3.one;
var gridPoint = grid.WorldToGrid(point);
var shifted = gridPoint - shift;
var rounded = RoundVector3(shifted);
var gridCell = rounded + shift;
return(system == CSystem.Grid ? gridCell : grid.GridToWorld(gridCell));
}
/// <summary>
/// Aligns a position vector onto the grid.
/// </summary>
/// <param name="grid">
/// The grid instance to extend.
/// </param>
/// <param name="vector">
/// The position in world-coordinates.
/// </param>
/// <param name="scale">
/// Used to determine whether to align to a cell or an edge, see
/// remarks.
/// </param>
/// <returns>
/// Position of the nearest face.
/// </returns>
/// <remarks>
/// <para>
/// The position will be interpreted to be the position of an
/// object that has the size <c>scale</c>. If the scale in an odd
/// multiple of the grid's spacing the position will be aligned to
/// an edge, otherwise to a cell.
/// </para>
/// </remarks>
public static Vector3 AlignVector3(this RectGrid grid, Vector3 vector, Vector3 scale)
{
const CoordinateSystem system = CoordinateSystem.Grid;
var vertex = grid.NearestVertex(vector, system);
var cell = grid.NearestCell(vector, system);
var spacing = grid.Spacing;
var aligned = new Vector3();
for (var i = 0; i < 3; ++i)
{
var fraction = Mathf.Max(scale[i] / spacing[i], 1f);
var even = Mathf.RoundToInt(fraction) % 2 == 0;
aligned[i] = even ? vertex[i] : cell[i];
}
return(grid.GridToWorld(aligned));
}