Computes conservative line raster/voxelization across a grid for use in walking a grid spatial data structure or or voxel scene searching for intersections. More...

Public Member Functions
	RayGridIterator (Ray ray, const Vector3int32 &numCells, const Vector3 &cellSize=Vector3(1, 1, 1), const Point3 &minBoundsLocation=Point3(0, 0, 0), const Point3int32 &minBoundsCellIndex=Point3int32(0, 0, 0))
	Initialize the iterator to the first grid cell hit by the ray and precompute traversal variables. More...

const Vector3 &	cellSize () const
	Size of each cell along each axis. More...

bool	containsRayOrigin () const
	True if this cell contains the ray origin. More...

int	enterAxis () const
	The axis along which the ray entered the cell; X = 0, Y = 1, Z = 2. More...

float	enterDistance () const
	Distance along the ray of the first intersection with the current cell (i.e., that given by m_index). More...

Vector3int32	enterNormal () const
	Outward-facing normal to the current grid cell along the partition just entered. More...

Point3	enterPoint () const
	Location where the ray entered the current grid cell. More...

float	exitDistance () const
	Distance from the ray origin to the exit point in this cell. More...

Point3	exitPoint () const
	Location where the ray exits the current grid cell. More...

const Vector3int32 &	index () const
	Current grid cell m_index. More...

bool	insideGrid () const
	True if index() refers to a valid cell inside the grid. More...

Vector3int32	numCells () const
	Extent of the grid in each dimension, in grid cell units. More...

RayGridIterator &	operator++ ()
	Increment the iterator, moving to the next grid cell. More...

const Ray &	ray () const
	The original ray. More...

const Vector3int32 &	step () const
	Sign of the direction that the ray moves along each axis; +/-1 or 0. More...

const Vector3 &	tDelta () const
	Size of one cell in units of t along each axis. More...

Protected Attributes
Vector3int32	m_boundaryIndex
	The value that the index will take on along each boundary when it just leaves the grid. More...

Vector3	m_cellSize
	Size of each cell along each axis. More...

bool	m_containsRayOrigin
	True if this cell contains the ray origin. More...

int	m_enterAxis
	The axis along which the ray entered the cell; X = 0, Y = 1, Z = 2. More...

float	m_enterDistance
	Distance along the ray of the first intersection with the current cell (i.e., that given by m_index). More...

Vector3	m_exitDistance
	Distance along the ray to the intersection with the next grid cell. More...

Vector3int32	m_index
	Current grid cell m_index. More...

bool	m_insideGrid
	True if index() refers to a valid cell inside the grid. More...

Vector3int32	m_numCells
	Extent of the grid in each dimension, in grid cell units. More...

Ray	m_ray
	The original ray. More...

Vector3int32	m_step
	Sign of the direction that the ray moves along each axis; +/-1 or 0. More...

Vector3	m_tDelta
	Size of one cell in units of t along each axis. More...

Detailed Description

Computes conservative line raster/voxelization across a grid for use in walking a grid spatial data structure or or voxel scene searching for intersections.

At each iteration, the iterator steps exactly one cell in exactly one dimension.

Example of this iterator applied to ray-primitive intersection in a grid:

bool firstRayIntersection(const Ray& ray, Value*& value, float& distance) const {
    for (RayGridIterator it(ray, cellSize); inBounds(it.index); ++it) {
        // Search for an intersection within this grid cell
        const Cell& c = cell(it.index);
        float maxdistance = min(distance, t.tExit);
        if (c.firstRayIntersection(ray, value, maxdistance)) {
            distance = maxdistance;
            return true;
        }
    }
}

See also: CollisionDetection, PointHashGrid, Ray, Intersect

Constructor & Destructor Documentation

◆ RayGridIterator()

G3D::RayGridIterator::RayGridIterator	(	Ray	ray,
		const Vector3int32 &	numCells,
		const Vector3 &	cellSize = `Vector3(1, 1, 1)`,
		const Point3 &	minBoundsLocation = `Point3(0, 0, 0)`,
		const Point3int32 &	minBoundsCellIndex = `Point3int32(0, 0, 0)`
	)

Initialize the iterator to the first grid cell hit by the ray and precompute traversal variables.

The grid is assumed to have a corner at (0,0,0) and extend along the canonical axes. For intersections grids transformed by a rigid body transformation, first transform the ray into the grid's object space with CFrame::rayToObjectSpace.

If the ray never passes through the grid, insideGrid() will be false immediately after intialization.

If using for 2D iteration, set numCells.z = 1 and ray.origin().z = 0.5

Parameters

cellSize	The extent of one cell
minBoundsLocation	The location of the lowest corner of grid cell minBoundsCellIndex along each axis. This translates the grid relative to the ray's coordinate frame.
minBoundsCellIndex	The index of the first grid cell. This allows operation with grids defined on negative indices. This translates all grid indices.

Member Function Documentation

◆ cellSize()

const Vector3& G3D::RayGridIterator::cellSize ( ) const

inline

Size of each cell along each axis.

◆ containsRayOrigin()

bool G3D::RayGridIterator::containsRayOrigin ( ) const

inline

True if this cell contains the ray origin.

◆ enterAxis()

int G3D::RayGridIterator::enterAxis ( ) const

inline

The axis along which the ray entered the cell; X = 0, Y = 1, Z = 2.

This is always set to X for the cell that contains the ray origin.

◆ enterDistance()

float G3D::RayGridIterator::enterDistance ( ) const

inline

Distance along the ray of the first intersection with the current cell (i.e., that given by m_index).

Zero for the cell that contains the ray origin.

◆ enterNormal()

Vector3int32 G3D::RayGridIterator::enterNormal ( ) const

inline

Outward-facing normal to the current grid cell along the partition just entered.

Initially zero.

◆ enterPoint()

Point3 G3D::RayGridIterator::enterPoint ( ) const

inline

Location where the ray entered the current grid cell.

◆ exitDistance()

float G3D::RayGridIterator::exitDistance ( ) const

inline

Distance from the ray origin to the exit point in this cell.

◆ exitPoint()

Point3 G3D::RayGridIterator::exitPoint ( ) const

inline

Location where the ray exits the current grid cell.

◆ index()

const Vector3int32& G3D::RayGridIterator::index ( ) const

inline

Current grid cell m_index.

◆ insideGrid()

bool G3D::RayGridIterator::insideGrid ( ) const

inline

True if index() refers to a valid cell inside the grid.

This is usually employed as the loop termination condition.

◆ numCells()

Vector3int32 G3D::RayGridIterator::numCells ( ) const

inline

Extent of the grid in each dimension, in grid cell units.

◆ operator++()

RayGridIterator& G3D::RayGridIterator::operator++ ( )

inline

Increment the iterator, moving to the next grid cell.

◆ ray()

const Ray& G3D::RayGridIterator::ray ( ) const

inline

The original ray.

◆ step()

const Vector3int32& G3D::RayGridIterator::step ( ) const

inline

Sign of the direction that the ray moves along each axis; +/-1 or 0.

◆ tDelta()

const Vector3& G3D::RayGridIterator::tDelta ( ) const

inline

Size of one cell in units of t along each axis.

Member Data Documentation

◆ m_boundaryIndex

Vector3int32 G3D::RayGridIterator::m_boundaryIndex

protected

The value that the index will take on along each boundary when it just leaves the grid.

Referenced by operator++().

◆ m_cellSize

Vector3 G3D::RayGridIterator::m_cellSize

protected

Size of each cell along each axis.

Referenced by cellSize().

◆ m_containsRayOrigin

bool G3D::RayGridIterator::m_containsRayOrigin

protected

True if this cell contains the ray origin.

Referenced by containsRayOrigin(), and operator++().

◆ m_enterAxis

int G3D::RayGridIterator::m_enterAxis

protected

The axis along which the ray entered the cell; X = 0, Y = 1, Z = 2.

This is always set to X for the cell that contains the ray origin.

Referenced by enterAxis(), enterNormal(), and operator++().

◆ m_enterDistance

float G3D::RayGridIterator::m_enterDistance

protected

Distance along the ray of the first intersection with the current cell (i.e., that given by m_index).

Zero for the cell that contains the ray origin.

Referenced by enterDistance(), enterPoint(), and operator++().

◆ m_exitDistance

Vector3 G3D::RayGridIterator::m_exitDistance

protected

Distance along the ray to the intersection with the next grid cell.

enterDistance and m_exitDistance can be used to bracket ray ray-primitive intersection tests within a cell.

Referenced by exitDistance(), exitPoint(), and operator++().

◆ m_index

Vector3int32 G3D::RayGridIterator::m_index

protected

Current grid cell m_index.

Referenced by index(), and operator++().

◆ m_insideGrid

bool G3D::RayGridIterator::m_insideGrid

protected

True if index() refers to a valid cell inside the grid.

This is usually employed as the loop termination condition.

Referenced by insideGrid(), and operator++().

◆ m_numCells

Vector3int32 G3D::RayGridIterator::m_numCells

protected

Extent of the grid in each dimension, in grid cell units.

Referenced by numCells().

◆ m_ray

Ray G3D::RayGridIterator::m_ray

protected

The original ray.

Referenced by enterPoint(), exitPoint(), and ray().

◆ m_step

Vector3int32 G3D::RayGridIterator::m_step

protected

Sign of the direction that the ray moves along each axis; +/-1 or 0.

Referenced by enterNormal(), operator++(), and step().

◆ m_tDelta

Vector3 G3D::RayGridIterator::m_tDelta

protected

Size of one cell in units of t along each axis.

Referenced by operator++(), and tDelta().

Public Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ RayGridIterator()

Member Function Documentation

◆ cellSize()

◆ containsRayOrigin()

◆ enterAxis()

◆ enterDistance()

◆ enterNormal()

◆ enterPoint()

◆ exitDistance()

◆ exitPoint()

◆ index()

◆ insideGrid()

◆ numCells()

◆ operator++()

◆ ray()

◆ step()

◆ tDelta()

Member Data Documentation

◆ m_boundaryIndex

◆ m_cellSize

◆ m_containsRayOrigin

◆ m_enterAxis

◆ m_enterDistance

◆ m_exitDistance

◆ m_index

◆ m_insideGrid

◆ m_numCells

◆ m_ray

◆ m_step

◆ m_tDelta