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module Utils.Physics exposing
( getNewPosAndSpeed
, getMove
, getWaveMove
, getSawToothMove
)
import Model.Vec2 exposing (..)
getNewPosAndSpeed : Float -> Vec2 -> (Float -> Float) -> (Vec2, Vec2) -> (Vec2, Vec2)
getNewPosAndSpeed dt dir computeSpeed (pos, speed) =
let move = getMove (computeSpeed dt) dir
acc = getAcc move speed
newPos = getNewPos dt acc speed pos
newSpeed = getNewSpeed dt acc speed
in ( newPos
, newSpeed
)
getMove : Float -> Vec2 -> Vec2
getMove dist dir =
if (isNull dir)
then {x = 0, y = 0}
else
let angle = atan2 dir.y dir.x
in { x = dist * cos angle
, y = dist * sin angle
}
getWaveMove : Float -> Vec2 -> Float -> Float -> Vec2
getWaveMove dist dir amplitude period =
let move = getMove dist dir
perpendMove =
getMove
(amplitude * (sin ((norm move) / period)))
(clockwiseRotate90 move)
in move `add` perpendMove
getSawToothMove : Float -> Vec2 -> Float -> Float -> Vec2
getSawToothMove dist dir amplitude period =
let move = getMove dist dir
perpendMove =
getMove
( let max = 1000 / period
middle = max / 2
modulo = toFloat <| round (norm move) % round max
in amplitude * (if modulo < middle then modulo else max - modulo) / middle
)
(clockwiseRotate90 move)
in move `add` perpendMove
getAcc : Vec2 -> Vec2 -> Vec2
getAcc move speed = (move `div` 300) `sub` (speed `div` 300)
getNewPos : Float -> Vec2 -> Vec2 -> Vec2 -> Vec2
getNewPos dt acc speed pos =
((dt^2 / 2) `mul` acc) `add` ((dt `mul` speed) `add` pos)
getNewSpeed : Float -> Vec2 -> Vec2 -> Vec2
getNewSpeed dt acc speed = add (mul dt acc) speed
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