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add function to get ID of first item found at location in quad tree (returns ~1 instead of NONE if no item is found)

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Humza Shahid
2025-01-17 21:48:18 +00:00
parent cbddc03a88
commit 560ef3f99a
1 changed files with 104 additions and 0 deletions
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104
fcore/quad-tree.sml
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@@ -34,6 +34,10 @@ sig
val hasCollisionAt: int * int * int * int * val hasCollisionAt: int * int * int * int *
int * int * int * int * int * int * int * int *
int * t -> bool int * t -> bool
val getItemID: int * int * int * int *
int * int * int * int *
t -> int
end end
structure QuadTree: QUAD_TREE = structure QuadTree: QUAD_TREE =
@@ -1273,4 +1277,104 @@ struct
| LEAF elements => | LEAF elements =>
hasCollisionAtVec hasCollisionAtVec
(itemX, itemY, itemWidth, itemHeight, itemID, 0, elements) (itemX, itemY, itemWidth, itemHeight, itemID, 0, elements)
fun getItemIDVec (iX, iY, iW, iH, pos, elements) =
if pos = Vector.length elements then
~1
else
let
val item = Vector.sub (elements, pos)
in
if isColliding (iX, iY, iW, iH, ~1, item) then #itemID item
else getItemIDVec (iX, iY, iW, iH, pos + 1, elements)
end
fun getItemID (itemX, itemY, itemW, itemH, quadX, quadY, quadW, quadH, tree) =
case tree of
NODE {topLeft, topRight, bottomLeft, bottomRight, elements} =>
let
val tryID = getItemIDVec (itemX, itemY, itemW, itemH, 0, elements)
in
if tryID = ~1 then
(case
whichQuadrant
(itemX, itemY, itemW, itemH, quadX, quadY, quadW, quadH)
of
TOP_LEFT =>
let
val halfWidth = quadW div 2
val halfHeight = quadH div 2
in
getItemID
( itemX
, itemY
, itemW
, itemH
, quadX
, quadY
, halfWidth
, halfHeight
, tree
)
end
| TOP_RIGHT =>
let
val halfWidth = quadW div 2
val halfHeight = quadH div 2
val middleX = quadX + halfWidth
in
getItemID
( itemX
, itemY
, itemW
, itemH
, middleX
, quadY
, halfWidth
, halfHeight
, tree
)
end
| BOTTOM_LEFT =>
let
val halfWidth = quadW div 2
val halfHeight = quadH div 2
val middleY = quadY + halfHeight
in
getItemID
( itemX
, itemY
, itemW
, itemH
, quadX
, middleY
, halfWidth
, halfHeight
, tree
)
end
| BOTTOM_RIGHT =>
let
val halfWidth = quadW div 2
val halfHeight = quadH div 2
val middleX = quadX + halfWidth
val middleY = quadY + halfHeight
in
getItemID
( itemX
, itemY
, itemW
, itemH
, middleX
, middleY
, halfWidth
, halfHeight
, tree
)
end
| PARENT_QUADRANT => ~1)
else
tryID
end
| LEAF elements => getItemIDVec (itemX, itemY, itemW, itemH, 0, elements)
end end