97 lines
2.4 KiB
Standard ML
97 lines
2.4 KiB
Standard ML
signature PHYSICS_INPUT =
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sig
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type t
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type patch
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(* constants for physics *)
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val moveBy: int
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val floatLimit: int
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val jumpLimit: int
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(* destructuring functions *)
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val getX: t -> int
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val getY: t -> int
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val getXAxis: t -> GameType.x_axis
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val getYAxis: t -> GameType.y_axis
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val W_X: int -> patch
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val W_Y: int -> patch
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val W_Y_AXIS: GameType.y_axis -> patch
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end
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functor MakePhysics(Fn: PHYSICS_INPUT) =
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struct
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open GameType
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fun getPatches input =
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let
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val x = Fn.getX input
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val y = Fn.getY input
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val xAxis = Fn.getXAxis input
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val yAxis = Fn.getYAxis input
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val desiredX =
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case xAxis of
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STAY_STILL => x
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| MOVE_LEFT => x - Fn.moveBy
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| MOVE_RIGHT => x + Fn.moveBy
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in
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case yAxis of
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ON_GROUND => [Fn.W_X desiredX]
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| FLOATING floated =>
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let
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val yAxis =
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if floated = Fn.floatLimit then FALLING
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else FLOATING (floated + 1)
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in
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[Fn.W_X desiredX, Fn.W_Y_AXIS yAxis]
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end
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| FALLING =>
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let val desiredY = y + Fn.moveBy
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in [Fn.W_X desiredX, Fn.W_Y desiredY]
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end
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| DROP_BELOW_PLATFORM =>
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let val desiredY = y + Fn.moveBy
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in [Fn.W_X desiredX, Fn.W_Y desiredY]
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end
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| JUMPING jumped =>
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if jumped + Fn.moveBy > Fn.jumpLimit then
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(* if we are above the jump limit, trigger a fall *)
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let val newYAxis = FLOATING 0
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in [Fn.W_X desiredX, Fn.W_Y_AXIS newYAxis]
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end
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else
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(* jump *)
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let
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val newJumped = jumped + Fn.moveBy
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val newYAxis = JUMPING newJumped
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val desiredY = y - Fn.moveBy
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in
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[Fn.W_X desiredX, Fn.W_Y desiredY, Fn.W_Y_AXIS newYAxis]
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end
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end
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end
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structure PlayerPhysics =
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MakePhysics
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(struct
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type t = GameType.player
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type patch = PlayerPatch.player_patch
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(* constants for physics *)
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val moveBy = Constants.movePlayerBy
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val floatLimit = Constants.floatLimit
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val jumpLimit = Constants.jumpLimit
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(* destructuring functions *)
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fun getX ({x, ...}: t) = x
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fun getY ({y, ...}: t) = y
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fun getXAxis ({xAxis, ...}: t) = xAxis
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fun getYAxis ({yAxis, ...}: t) = yAxis
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val W_X = PlayerPatch.W_X
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val W_Y = PlayerPatch.W_Y
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val W_Y_AXIS = PlayerPatch.W_Y_AXIS
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end)
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