/// <summary>
/// casts a line through the spatial hash and fills the hits array up with any colliders that the line hits
/// </summary>
/// <returns>the number of Colliders returned</returns>
/// <param name="start">Start.</param>
/// <param name="end">End.</param>
/// <param name="hits">Hits.</param>
/// <param name="layerMask">Layer mask.</param>
public int linecast(Vector2 start, Vector2 end, RaycastHit[] hits, int layerMask)
{
var ray = new Ray2D(start, end);
_raycastParser.start(ref ray, hits, layerMask);
// get our start/end position in the same space as our grid
start.X *= _inverseCellSize;
start.Y *= _inverseCellSize;
var endCell = cellCoords(end.X, end.Y);
// TODO: check gridBounds to ensure the ray starts/ends in the grid. watch out for end cells since they report out of bounds due to int comparison
// what voxel are we on
var intX = Mathf.fastFloorToInt(start.X);
var intY = Mathf.fastFloorToInt(start.Y);
// which way we go
var stepX = Math.Sign(ray.direction.X);
var stepY = Math.Sign(ray.direction.Y);
// Calculate cell boundaries. when the step is positive, the next cell is after this one meaning we add 1.
// If negative, cell is before this one in which case dont add to boundary
var boundaryX = intX + (stepX > 0 ? 1 : 0);
var boundaryY = intY + (stepY > 0 ? 1 : 0);
// determine the value of t at which the ray crosses the first vertical voxel boundary. same for y/horizontal.
// The minimum of these two values will indicate how much we can travel along the ray and still remain in the current voxel
// may be infinite for near vertical/horizontal rays
var tMaxX = (boundaryX - start.X) / ray.direction.X;
var tMaxY = (boundaryY - start.Y) / ray.direction.Y;
if (ray.direction.X == 0f)
{
tMaxX = float.PositiveInfinity;
}
if (ray.direction.Y == 0f)
{
tMaxY = float.PositiveInfinity;
}
// how far do we have to walk before crossing a cell from a cell boundary. may be infinite for near vertical/horizontal rays
var tDeltaX = stepX / ray.direction.X;
var tDeltaY = stepY / ray.direction.Y;
// start walking and returning the intersecting cells.
var cell = cellAtPosition(intX, intY);
//debugDrawCellDetails( intX, intY, cell != null ? cell.Count : 0 );
if (cell != null && _raycastParser.checkRayIntersection(intX, intY, cell))
{
Array.Sort(hits, RaycastResultParser.compareRaycastHits);
_raycastParser.reset();
return(_raycastParser.hitCounter);
}
while (intX != endCell.X || intY != endCell.Y)
{
if (tMaxX < tMaxY)
{
intX += stepX;
tMaxX += tDeltaX;
}
else
{
intY += stepY;
tMaxY += tDeltaY;
}
cell = cellAtPosition(intX, intY);
if (cell != null && _raycastParser.checkRayIntersection(intX, intY, cell))
{
Array.Sort(hits, RaycastResultParser.compareRaycastHits);
_raycastParser.reset();
return(_raycastParser.hitCounter);
}
}
// make sure we are reset
Array.Sort(hits, RaycastResultParser.compareRaycastHits);
_raycastParser.reset();
return(_raycastParser.hitCounter);
}
/// <summary>
/// casts a line through the spatial hash and fills the hits array up with any colliders that the line hits.
/// https://github.com/francisengelmann/fast_voxel_traversal/blob/master/main.cpp
/// http://www.cse.yorku.ca/~amana/research/grid.pdf
/// </summary>
/// <returns>the number of Colliders returned</returns>
/// <param name="start">Start.</param>
/// <param name="end">End.</param>
/// <param name="hits">Hits.</param>
/// <param name="layerMask">Layer mask.</param>
public int linecast(Vector2 start, Vector2 end, RaycastHit[] hits, int layerMask)
{
var ray = new Ray2D(start, end);
_raycastParser.start(ref ray, hits, layerMask);
// get our start/end position in the same space as our grid
var currentCell = cellCoords(start.X, start.Y);
var lastCell = cellCoords(end.X, end.Y);
// what direction are we incrementing the cell checks?
var stepX = Math.Sign(ray.direction.X);
var stepY = Math.Sign(ray.direction.Y);
// we make sure that if we're on the same line or row we don't step in the unneeded direction
if (currentCell.X == lastCell.X)
{
stepX = 0;
}
if (currentCell.Y == lastCell.Y)
{
stepY = 0;
}
// Calculate cell boundaries. when the step is positive, the next cell is after this one meaning we add 1.
// If negative, cell is before this one in which case dont add to boundary
var xStep = stepX < 0 ? 0f : (float)stepX;
var yStep = stepY < 0 ? 0f : (float)stepY;
var nextBoundaryX = ((float)currentCell.X + xStep) * _cellSize;
var nextBoundaryY = ((float)currentCell.Y + yStep) * _cellSize;
// determine the value of t at which the ray crosses the first vertical voxel boundary. same for y/horizontal.
// The minimum of these two values will indicate how much we can travel along the ray and still remain in the current voxel
// may be infinite for near vertical/horizontal rays
var tMaxX = ray.direction.X != 0 ? (nextBoundaryX - ray.start.X) / ray.direction.X : float.MaxValue;
var tMaxY = ray.direction.Y != 0 ? (nextBoundaryY - ray.start.Y) / ray.direction.Y : float.MaxValue;
// how far do we have to walk before crossing a cell from a cell boundary. may be infinite for near vertical/horizontal rays
var tDeltaX = ray.direction.X != 0 ? _cellSize / (ray.direction.X * stepX) : float.MaxValue;
var tDeltaY = ray.direction.Y != 0 ? _cellSize / (ray.direction.Y * stepY) : float.MaxValue;
// start walking and returning the intersecting cells.
var cell = cellAtPosition(currentCell.X, currentCell.Y);
// Debug.log( $"cell: {currentCell.X}, {currentCell.Y}" );
// debugDrawCellDetails( intX, intY, cell != null ? cell.Count : 10 );
if (cell != null && _raycastParser.checkRayIntersection(currentCell.X, currentCell.Y, cell))
{
_raycastParser.reset();
return(_raycastParser.hitCounter);
}
while (currentCell.X != lastCell.X || currentCell.Y != lastCell.Y)
{
if (tMaxX < tMaxY)
{
// HACK: ensures we never overshoot our values
currentCell.X = (int)Mathf.approach(currentCell.X, lastCell.X, Math.Abs(stepX));
// currentCell.X += stepX;
tMaxX += tDeltaX;
}
else
{
currentCell.Y = (int)Mathf.approach(currentCell.Y, lastCell.Y, Math.Abs(stepY));
// currentCell.Y += stepY;
tMaxY += tDeltaY;
}
// Debug.log( $"cell: {currentCell.X}, {currentCell.Y}" );
cell = cellAtPosition(currentCell.X, currentCell.Y);
if (cell != null && _raycastParser.checkRayIntersection(currentCell.X, currentCell.Y, cell))
{
_raycastParser.reset();
return(_raycastParser.hitCounter);
}
}
// make sure we are reset
_raycastParser.reset();
return(_raycastParser.hitCounter);
}