Custom Physics System

--[[ This is the Physics Manager ]]

local RunService = game:GetService("RunService")

local constants = {
    GRAVITY = 1,
    AIR_RESISTANCE = 0.08
}

local Objects = {}

function PrepareObject(Object: BasePart)
    if not Object then return end

    print("Prepared "..Object.Name)

    Object:SetAttribute("Force", Vector3.new(0, 0, 0))

    if Object:HasTag("AlwaysIgnore") then
        Object:SetAttribute("IgnorePhysics", true)
        return
    end

    Object:SetAttribute("IgnorePhysics", false)
end

function Initialize()
    local gameArray = game:GetDescendants()
    if gameArray then
        for _, item in ipairs(gameArray) do
            if item:IsA("BasePart") and not item:IsA("Terrain") then
                PrepareObject(item)
                table.insert(Objects, item)
            end
        end
    end
end

function CalculatePosition(Object: BasePart, deltaTime: number) : Vector3
    if not Object then return end

    local Force: Vector3 = Object:GetAttribute("Force")
    local IgnorePhysics: boolean = Object:GetChildren("IgnorePhysics")

    if Force and IgnorePhysics then
        if IgnorePhysics == true then
            return Object.Position
        end

        local newPosition = Object.Position + Force

        return newPosition
    end
end

function CalculateForce(Object: BasePart, deltaTime: number) : Vector3
    if not Object then return end

    local Force = Object:GetAttribute("Force")

    if Force then
        return Force + Vector3.new(constants.AIR_RESISTANCE * (math.pow(Force.X, 2) * deltaTime), (Force.Y - constants.GRAVITY) * deltaTime, constants.AIR_RESISTANCE * (math.pow(Force.Z, 2) * deltaTime))
    end
end

function InvertForce(Object: BasePart) : Vector3
    local Force = Object:GetAttribute("Force")
    if Force then
        if Force.Y <= 0 then
            if Force.Y < 1 and Force.Y > -1 then
                Force = Vector3.new(Force.X, 0, Force.Z)
            end

            local newForce = Vector3.new(Force.X, -Force.Y / 2.5, Force.Z)

            return newForce
        else
            return Force
        end
    end
end

function IsColliding(Object: BasePart) : boolean
    local objectsColliding = Object:GetTouchingParts()
    if #objectsColliding ~= 0 then
        return true
    else
        return false
    end
end

function GetObjectsColliding(Object: BasePart): {Instance}
    local objectsColliding = Object:GetTouchingParts()

    return objectsColliding
end

function SetOutOfPart(Object: BasePart, CollidingObject: BasePart)
    local O_Position = Object.Position
    local CO_Position = CollidingObject.Position

    local O_Size = Object.Size
    local CO_Size = CollidingObject.Size


end

function UpdatePhysics(deltaTime: number)
    for _, object in ipairs(Objects) do
        if object:GetAttribute("IgnorePhysics") == false then
            object.Position = CalculatePosition(object, deltaTime)
            object:SetAttribute("Force", CalculateForce(object, deltaTime))

            local colliding = IsColliding(object)
            if colliding == true then
                object:SetAttribute("Force", InvertForce(object))
            end
        end
    end
end

Initialize()

RunService.Heartbeat:Connect(UpdatePhysics)