SATv2

--!optimize 2
--!native

local PointToWorldSpace = CFrame.identity.PointToWorldSpace

local BOX_POINT_2 = Vector3.new( 1, 1,-1)
local BOX_POINT_3 = Vector3.new( 1,-1, 1)
local BOX_POINT_4 = Vector3.new( 1,-1,-1)
local BOX_POINT_5 = Vector3.new(-1, 1, 1)
local BOX_POINT_6 = Vector3.new(-1, 1,-1)
local BOX_POINT_7 = Vector3.new(-1,-1, 1)

--

local function GetBoxData(box1CFrame: CFrame, box1Size: Vector3, box2CFrame: CFrame, box2Size: Vector3)
    local box1HalfSize = box1Size / 2
    local box2HalfSize = box2Size / 2

    return {
        PointToWorldSpace(box1CFrame,
            box1HalfSize,
            box1HalfSize * BOX_POINT_2,
            box1HalfSize * BOX_POINT_3,
            box1HalfSize * BOX_POINT_4,
            box1HalfSize * BOX_POINT_5,
            box1HalfSize * BOX_POINT_6,
            box1HalfSize * BOX_POINT_7,
            -box1HalfSize
        )
    }, {
        PointToWorldSpace(box2CFrame,
            box2HalfSize,
            box2HalfSize * BOX_POINT_2,
            box2HalfSize * BOX_POINT_3,
            box2HalfSize * BOX_POINT_4,
            box2HalfSize * BOX_POINT_5,
            box2HalfSize * BOX_POINT_6,
            box2HalfSize * BOX_POINT_7,
            -box2HalfSize
        )
    }, {
        [box1HalfSize.X] = box1CFrame.XVector,
        [box1HalfSize.Y] = box1CFrame.YVector,
        [box1HalfSize.Z] = box1CFrame.ZVector
    }, {
        [box2HalfSize.X] = box2CFrame.XVector,
        [box2HalfSize.Y] = box2CFrame.YVector,
        [box2HalfSize.Z] = box2CFrame.ZVector
    }
end

local function SATCheck(box1CFrame: CFrame, box1Size: Vector3, box2CFrame: CFrame, box2Size: Vector3): boolean
    local box1Points, box2Points, box1Normals, box2Normals = GetBoxData(box1CFrame, box1Size, box2CFrame, box2Size)

    local box1Pos = box1CFrame.Position
    local box2Pos = box2CFrame.Position

    --

    for axisSize, box1normal in box1Normals do
        local p1,p2,p3,p4,p5,p6,p7,p8=
            vector.dot(box1normal, box2Points[1]),
            vector.dot(box1normal, box2Points[1]),
            vector.dot(box1normal, p3),
            vector.dot(box1normal, p4),
            vector.dot(box1normal, p5),
            vector.dot(box1normal, p6),
            vector.dot(box1normal, p7),
            vector.dot(box1normal, p8),

        local originDist = vector.dot(box1Pos, box1normal)

        if
            (originDist + axisSize) < math.min(p1,p2,p3,p4,p5,p6,p7,p8)
            or (originDist - axisSize) > math.max(p1,p2,p3,p4,p5,p6,p7,p8) then
            return false --returns false if theres a seperating axis
        end
    end

    for axisSize, box2Normal in box2Normals do
        local box1Min = math.huge
        local box1Max = -math.huge

        for _, point in box1Points do
            local dist = vector.dot(box2Normal, point)

            if dist > box1Max then
                box1Max = dist
            end

            if dist < box1Min then
                box1Min = dist
            end
        end

        local originDist = vector.dot(box2Pos, box2Normal)

        if (originDist + axisSize) < box1Min or (originDist - axisSize) > box1Max then
            return false
        end

        --

        for _, box1Normal in box1Normals do
            local dir = vector.cross(box1Normal, box2Normal)

            local box1Min = math.huge
            local box1Max = -math.huge

            local box2Min = math.huge
            local box2Max = -math.huge

            for _, point in box1Points do
                local dist = vector.dot(dir, point)

                if dist > box1Max then
                    box1Max = dist
                end

                if dist < box1Min then
                    box1Min = dist
                end
            end

            for _, point in box2Points do
                local dist = vector.dot(dir, point)

                if dist > box2Max then
                    box2Max = dist
                end

                if dist < box2Min then
                    box2Min = dist
                end
            end

            if box1Max < box2Min or box1Min > box2Max then
                return false
            end
        end
    end

    return true
end

return SATCheck