interpolateBetween

[pa3ck]

Hi guys, I was looking at the interpolateBetween function, but I did not get it, I can't understand how it works.

The example was:

local g_Window = nil 
addCommandHandler("window", 
function () 
    if g_Window then return end 
  
    g_Window = {} 
  
    local screenWidth, screenHeight = guiGetScreenSize() 
    g_Window.windowWidth, g_Window.windowHeight = 400, 315 
    local left = screenWidth/2 - g_Window.windowWidth/2 
    local top = screenHeight/2 - g_Window.windowHeight/2 
  
    g_Window.window = guiCreateWindow(left, top, g_Window.windowWidth, g_Window.windowHeight, "Interpolation on GUI", false) 
  
    g_Window.closeBtn = guiCreateButton(320, 285, 75, 23, "Close", false, g_Window.window) 
  
    guiWindowSetSizable(g_Window.window, false) 
    guiWindowSetMovable(g_Window.window, false) 
    guiSetEnabled(g_Window.window, false) 
    guiSetVisible(g_Window.window, false) 
  
    g_Window.startTime = getTickCount() 
    g_Window.startSize = {0, 0} 
    g_Window.endSize = {g_Window.windowWidth, g_Window.windowHeight} 
    g_Window.endTime = g_Window.startTime + 1000 
    addEventHandler("onClientRender", getRootElement(), popWindowUp) 
end) 
  
function on_closeBtn_clicked(button, state, absoluteX, absoluteY) 
    if (button ~= "left") or (state ~= "up") then 
        return 
    end 
  
    if not g_Window then return end 
  
    showCursor(false) 
    guiSetEnabled(g_Window.window, false) 
    guiWindowSetMovable(g_Window.window, false) 
  
    local screenWidth, screenHeight = guiGetScreenSize() 
    local posX, posY = guiGetPosition(g_Window.window, false) 
  
    g_Window.startTime = getTickCount() 
    g_Window.startSize = {g_Window.windowWidth, g_Window.windowHeight} 
    g_Window.startCenter =  
    { 
        posX + g_Window.windowWidth/2, 
        posY + g_Window.windowHeight/2, 
    } 
  
    g_Window.endSize = {0, 0} 
    g_Window.endTime = g_Window.startTime + 1000 
    g_Window.endCenter =  
    { 
        screenWidth,  
        screenHeight 
    } 
  
    addEventHandler("onClientRender", getRootElement(), popWindowDown) 
end 
  
function popWindowUp() 
    local now = getTickCount() 
    local elapsedTime = now - g_Window.startTime 
    local duration = g_Window.endTime - g_Window.startTime 
    local progress = elapsedTime / duration 
  
    local width, height, _ = interpolateBetween (  
        g_Window.startSize[1], g_Window.startSize[2], 0,  
        g_Window.endSize[1], g_Window.endSize[2], 0,  
        progress, "OutElastic") 
  
    guiSetSize(g_Window.window, width, height, false) 
  
    local screenWidth, screenHeight = guiGetScreenSize() 
    guiSetPosition(g_Window.window, screenWidth/2 - width/2, screenHeight/2 - height/2, false) 
  
    if not guiGetVisible(g_Window.window) then 
        guiSetVisible(g_Window.window, true) 
        guiBringToFront(g_Window.window) 
    end 
  
    if now >= g_Window.endTime then 
        guiSetEnabled(g_Window.window, true) 
  
        guiBringToFront(g_Window.window) 
        removeEventHandler("onClientRender", getRootElement(), popWindowUp) 
        addEventHandler("onClientGUIClick", g_Window.closeBtn, on_closeBtn_clicked, false) 
        showCursor(true) 
        guiWindowSetMovable(g_Window.window, true) 
    end 
end 
  
function popWindowDown() 
    local now = getTickCount() 
    local elapsedTime = now - g_Window.startTime 
    local duration = g_Window.endTime - g_Window.startTime 
    local progress = elapsedTime / duration 
  
    local width, height, _ = interpolateBetween (  
        g_Window.startSize[1], g_Window.startSize[2], 0,  
        g_Window.endSize[1], g_Window.endSize[2], 0,  
        progress, "InQuad") 
  
    guiSetSize(g_Window.window, width, height, false) 
  
    local centerX, centerY, _ = interpolateBetween (  
        g_Window.startCenter[1], g_Window.startCenter[2], 0,  
        g_Window.endCenter[1], g_Window.endCenter[2], 0,  
        progress, "InQuad") 
  
    guiSetPosition(g_Window.window, centerX - width/2, centerY - height/2, false) 
  
    if now >= g_Window.endTime then 
        removeEventHandler("onClientRender", getRootElement(), popWindowDown) 
        destroyElement(g_Window.window) 
        g_Window = nil 
    end 
end 

I would need further explanation on this example code... Could anyone explain it further more please?