Struct SquareCornerCoord

Represents a corner vertex in a square grid.

Implements
Inherited Members
Namespace: Scylla.Core.Structures
Assembly: ScyllaCore.dll
Syntax
public readonly struct SquareCornerCoord : IEquatable<SquareCornerCoord>
Remarks

A square grid of W columns and H rows has (W+1) * (H+1) corner vertices, one at each lattice point. The coordinate (c, r) identifies the northwest (top-left) vertex of the cell at position (c, r). Equivalently:

  • Corner (0, 0) is the top-left vertex of cell (0, 0).
  • Corner (W, H) is the bottom-right vertex of the last cell (W-1, H-1).

Every interior corner is shared by up to four cells. The four cells that share corner (c, r) are (c, r), (c-1, r), (c-1, r-1), and (c, r-1). Use GetCellsNonAlloc(SquareCornerCoord, Span<SquareCoord>) to retrieve them without allocation.

The static topology helpers (GetCellsNonAlloc(SquareCornerCoord, Span<SquareCoord>), GetEdgesNonAlloc(SquareCornerCoord, Span<SquareEdgeCoord>), GetCornersOfCellNonAlloc(SquareCoord, Span<SquareCornerCoord>)) write into caller-supplied Span<T> buffers to remain allocation-free.

Constructors

SquareCornerCoord(int, int)

Creates a new square corner coordinate at the specified lattice point.

Declaration
public SquareCornerCoord(int col, int row)
Parameters
Type Name Description
int col

The column index of the lattice point. Valid range for a grid of width W is 0 to W (inclusive).
int row

The row index of the lattice point. Valid range for a grid of height H is 0 to H (inclusive).

Fields

Col

The column index of the lattice point. Corresponds to the left boundary of column Col in cell coordinates.

Declaration
public readonly int Col
Field Value
Type Description
int

Row

The row index of the lattice point. Corresponds to the top boundary of row Row in cell coordinates.

Declaration
public readonly int Row
Field Value
Type Description
int

Methods

Equals(SquareCornerCoord)

Determines whether this corner coordinate equals other.

Declaration
public bool Equals(SquareCornerCoord other)
Parameters
Type Name Description
SquareCornerCoord other

The corner coordinate to compare with.
Returns
Type Description
bool

true if both Col and Row are equal; false otherwise.

Equals(object)

Determines whether this corner coordinate equals an arbitrary object.

Declaration
public override bool Equals(object obj)
Parameters
Type Name Description
object obj

The object to compare with. May be null.
Returns
Type Description
bool

true if obj is a SquareCornerCoord with the same column and row values; false otherwise.
Overrides

GetCellsNonAlloc(SquareCornerCoord, Span<SquareCoord>)

Writes the (up to) four cells that share corner into buffer.

Declaration
public static int GetCellsNonAlloc(SquareCornerCoord corner, Span<SquareCoord> buffer)
Parameters
Type Name Description
SquareCornerCoord corner

The corner whose adjacent cells are requested.
Span<SquareCoord> buffer

A Span<T> of at least 4 elements to receive the cell coordinates. If the span is smaller than 4, the method writes nothing and returns 0.
Returns
Type Description
int

The number of cell coordinates written: always 4 when the buffer is large enough, or 0 when the buffer has fewer than 4 elements.
Remarks

Corner (c, r) is the northwest vertex of cell (c, r). The four cells that share this vertex are written in the following order:

  • Index 0: (c, r) - southeast cell (below-right)
  • Index 1: (c-1, r) - southwest cell (below-left)
  • Index 2: (c-1, r-1) - northwest cell (above-left)
  • Index 3: (c, r-1) - northeast cell (above-right)

The returned coordinates are not bounds-checked; callers should validate them against the grid before use.

GetCornersOfCellNonAlloc(SquareCoord, Span<SquareCornerCoord>)

Writes the four corner vertices of cell into buffer.

Declaration
public static int GetCornersOfCellNonAlloc(SquareCoord cell, Span<SquareCornerCoord> buffer)
Parameters
Type Name Description
SquareCoord cell

The cell whose four corner vertices are requested.
Span<SquareCornerCoord> buffer

A Span<T> of at least 4 elements to receive the corner coordinates. If the span is smaller than 4, the method writes nothing and returns 0.
Returns
Type Description
int

The number of corner coordinates written: always 4 when the buffer is large enough, or 0 when the buffer has fewer than 4 elements.
Remarks

The four corners of cell (c, r) are written in clockwise order starting from the northwest (top-left) vertex:

  • Index 0: (c, r) - northwest
  • Index 1: (c+1, r) - northeast
  • Index 2: (c+1, r+1) - southeast
  • Index 3: (c, r+1) - southwest

These corner coordinates can be converted to world-space positions using GridToWorld(SquareCoord), taking into account that each corner is offset from the cell center by half a cell width/height.

GetEdgesNonAlloc(SquareCornerCoord, Span<SquareEdgeCoord>)

Writes the four canonical edges that meet at corner into buffer.

Declaration
public static int GetEdgesNonAlloc(SquareCornerCoord corner, Span<SquareEdgeCoord> buffer)
Parameters
Type Name Description
SquareCornerCoord corner

The corner whose incident edges are requested.
Span<SquareEdgeCoord> buffer

A Span<T> of at least 4 elements to receive the edge coordinates. If the span is smaller than 4, the method writes nothing and returns 0.
Returns
Type Description
int

The number of edge coordinates written: always 4 when the buffer is large enough, or 0 when the buffer has fewer than 4 elements.
Remarks

Using the canonical N/W encoding (see SquareEdgeDirection), the four edges that terminate at corner (c, r) are:

  • Index 0: (c, r, N) - N edge of the cell to the south-east
  • Index 1: (c, r, W) - W edge of the cell to the south-east
  • Index 2: (c-1, r, N) - N edge of the cell to the south-west
  • Index 3: (c, r-1, W) - W edge of the cell to the north-east

GetHashCode()

Returns a hash code for this corner coordinate based on its column and row values.

Declaration
public override int GetHashCode()
Returns
Type Description
int

A hash code suitable for use in hash-based collections such as Dictionary<TKey, TValue>.
Overrides

ToString()

Returns a human-readable string representation of this corner coordinate.

Declaration
public override string ToString()
Returns
Type Description
string

A string in the format (Col, Row), e.g. (4, 2).
Overrides

Operators

operator +(SquareCornerCoord, SquareCornerCoord)

Adds two corner coordinates component-wise, computing a new lattice point offset from a by b.

Declaration
public static SquareCornerCoord operator +(SquareCornerCoord a, SquareCornerCoord b)
Parameters
Type Name Description
SquareCornerCoord a
SquareCornerCoord b
Returns
Type Description
SquareCornerCoord

operator ==(SquareCornerCoord, SquareCornerCoord)

Returns true if left and right refer to the same lattice point (equal column and row).

Declaration
public static bool operator ==(SquareCornerCoord left, SquareCornerCoord right)
Parameters
Type Name Description
SquareCornerCoord left
SquareCornerCoord right
Returns
Type Description
bool

operator !=(SquareCornerCoord, SquareCornerCoord)

Returns true if left and right refer to different lattice points.

Declaration
public static bool operator !=(SquareCornerCoord left, SquareCornerCoord right)
Parameters
Type Name Description
SquareCornerCoord left
SquareCornerCoord right
Returns
Type Description
bool

operator *(SquareCornerCoord, int)

Scales both components of coord by scalar.

Declaration
public static SquareCornerCoord operator *(SquareCornerCoord coord, int scalar)
Parameters
Type Name Description
SquareCornerCoord coord
int scalar
Returns
Type Description
SquareCornerCoord

operator *(int, SquareCornerCoord)

Scales both components of coord by scalar. Commutative overload of coord * scalar.

Declaration
public static SquareCornerCoord operator *(int scalar, SquareCornerCoord coord)
Parameters
Type Name Description
int scalar
SquareCornerCoord coord
Returns
Type Description
SquareCornerCoord

operator -(SquareCornerCoord, SquareCornerCoord)

Subtracts b from a component-wise, returning the displacement vector between the two lattice points.

Declaration
public static SquareCornerCoord operator -(SquareCornerCoord a, SquareCornerCoord b)
Parameters
Type Name Description
SquareCornerCoord a
SquareCornerCoord b
Returns
Type Description
SquareCornerCoord

operator -(SquareCornerCoord)

Returns a new corner coordinate with both components negated, mirroring coord through the origin.

Declaration
public static SquareCornerCoord operator -(SquareCornerCoord coord)
Parameters
Type Name Description
SquareCornerCoord coord
Returns
Type Description
SquareCornerCoord

Implements

See Also