linee

local points, sticks = {}, {}
local gravity = 0.1

function point(x, y, z, pinned)
    return {
        pos = Vector3(x, y, z),
        oldPos = Vector3(x, y, z),
        pinned = (pinned or false)
    }
end

function stick(a, b)
    return {
        p0 = points[a],
        p1 = points[b],
        length = getDistanceBetweenPoints3D(points[a].pos, points[b].pos)*2
    }
end

function updatePoints(dt)
    for k,v in pairs(points) do
        if not v.pinned then
            if isLineOfSightClear(v.pos, Vector3(v.pos.x, v.pos.y, v.pos.z - gravity*dt), true, false, false, true) then
                v.pos.z = v.pos.z - gravity*dt
            end
            while not isLineOfSightClear(v.pos, Vector3(v.pos.x, v.pos.y, v.pos.z + 0.1), true, false, false, true) do
                v.pos.z = v.pos.z + 0.1
            end
        end
    end
end

function updateSticks(dt)
    for k,v in pairs(sticks) do
        local dx = v.p1.pos.x - v.p0.pos.x
        local dy = v.p1.pos.y - v.p0.pos.y
        local dz = v.p1.pos.z - v.p0.pos.z
        local dist = math.sqrt(dx * dx + dy * dy + dz * dz)
        local diff = v.length - dist

        local percent = diff / dist / 2
        local offsetX = dx * percent
        local offsetY = dy * percent
        local offsetZ = dz * percent

        if not v.p0.pinned then
            v.p0.pos.x = v.p0.pos.x - offsetX
            v.p0.pos.y = v.p0.pos.y - offsetY
            v.p0.pos.z = v.p0.pos.z - offsetZ
        end

        if not v.p1.pinned then
            v.p1.pos.x = v.p1.pos.x + offsetX
            v.p1.pos.y = v.p1.pos.y + offsetY
            v.p1.pos.z = v.p1.pos.z + offsetZ
        end
    end
end

function renderPoints()
    for k,v in pairs(points) do
        local x, y = getScreenFromWorldPosition(v.pos)
        if x and y then
            dxDrawRectangle(x-2, y-2, 4, 4, white)
        end
    end
end

function renderSticks()
    for k,v in pairs(sticks) do
        dxDrawLine3D(v.p0.pos, v.p1.pos, tocolor(0, 0, 0), 3)
    end
end

function init()
    table.insert(points, point(0, 0, 6, true))
    for i = 1, 20 do
        table.insert(points, point(0, 0, 6 - 0.1*i))
        table.insert(sticks, stick(i, i+1))
    end
end
init()

addEventHandler("onClientPreRender", root, function(dt)
    updatePoints(dt/100)
    updateSticks(dt/10)
    --renderPoints()
    renderSticks()
end)



-- debug

addEventHandler("onClientRender", root, function(dt)
    points[1].pos = Vector3(getElementPosition(localPlayer))
end)