61 lines
1.6 KiB
Standard ML
61 lines
1.6 KiB
Standard ML
signature QUAD_FOLDER =
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sig
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type env
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type state
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val fold: int * env * state -> state
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end
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signature MAKE_QUAD_TREE_FOLD =
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sig
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structure Fn: QUAD_FOLDER
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val foldRegion: int * int * int * int *
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Fn.env * Fn.state * QuadTreeType.t
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-> Fn.state
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end
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functor MakeQuadTreeFold(Fn: QUAD_FOLDER): MAKE_QUAD_TREE_FOLD =
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struct
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structure Fn = Fn
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open QuadTreeType
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fun foldRegionVec (rx, ry, rw, rh, env, state, pos, elements) =
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if pos = Vector.length elements then
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state
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else
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let
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val item = Vector.sub (elements, pos)
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val state =
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if isCollidingItem (rx, ry, rw, rh, ~1, item) then
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Fn.fold (#itemID item, env, state)
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else
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state
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in
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foldRegionVec (rx, ry, rw, rh, env, state, pos + 1, elements)
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end
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fun foldRegion (rx, ry, rw, rh, env, state, tree) =
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case tree of
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NODE {nodes, x, y, w, h} =>
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if isCollidingPlus (rx, ry, rw, rh, x, y, w, h) then
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let
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val state =
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foldRegion (rx, ry, rw, rh, env, state, Vector.sub (nodes, tlIdx))
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val state =
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foldRegion (rx, ry, rw, rh, env, state, Vector.sub (nodes, trIdx))
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val state =
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foldRegion (rx, ry, rw, rh, env, state, Vector.sub (nodes, blIdx))
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in
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foldRegion (rx, ry, rw, rh, env, state, Vector.sub (nodes, brIdx))
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end
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else
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state
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| LEAF {items, x, y, w, h} =>
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if isCollidingPlus (rx, ry, rw, rh, x, y, w, h) then
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foldRegionVec (rx, ry, rw, rh, env, state, 0, items)
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else
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state
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end
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