local m_fOverheadNumberZSpeed = 170.0
local m_OverheadNumberColorShieldMin = rgb(255, 255, 255)
local m_OverheadNumberColorShieldMax = rgb(83, 83, 255)
local m_fOverheadNumberTotalTime = 1.70
local m_fOverheadNumberFadeTime = 1.30
local m_fOverheadNumberScaleTime = 0.450
local m_fOverheadNumberMaxScaleAmount = 0.650
local m_fOverheadNumberColorizeTimeMin = 0.250
local m_fOverheadNumberColorizeTimeMax = 0.50

-- Linear interpolation utility function
function lerp(a, b, x)
   return a + (b - a) * x
end

-- Simple number creation, just add the number to the list
function onDamageNumberCreate(dam_nums, number, loc, is_shield)
   local num = DamageNumber(number, m_fOverheadNumberTotalTime, loc, is_shield)
   num.color = damageNumbersColorMin
   dam_nums:add(num)
end

-- Numbers update, most of the code is there to match HiRez's implementation
function onDamageNumberUpdate(dam_nums, hud, delta)
   local i = 0
   while i < dam_nums:size() do
      local curr = dam_nums:get(i)
      curr.time = curr.time - delta
      if curr.time <= 0 then
         dam_nums:remove(i)
         i = i - 1
      else
         local accu_time = 1.70 - curr.time
         if curr.number > damageNumbersLimit then
            curr.location.z = curr.location.z + delta * m_fOverheadNumberZSpeed
         end
         if accu_time > m_fOverheadNumberColorizeTimeMax then
            if curr.shieldDamage then
               curr.color = m_OverheadNumberColorShieldMax
            else
               curr.color = damageNumbersColorMax
            end
         else
            if accu_time > m_fOverheadNumberColorizeTimeMin and m_fOverheadNumberColorizeTimeMin < m_fOverheadNumberColorizeTimeMax then
               local alpha = (m_fOverheadNumberColorizeTimeMin - (m_fOverheadNumberColorizeTimeMax - accu_time)) / (m_fOverheadNumberColorizeTimeMax - m_fOverheadNumberColorizeTimeMin)
               local cmin, cmax

               if curr.shieldDamage then
                  cmin = m_OverheadNumberColorShieldMin
                  cmax = m_OverheadNumberColorShieldMax
               else
                  cmin = damageNumbersColorMin
                  cmax = damageNumbersColorMax
               end
               curr.color.r = math.floor(lerp(cmin.r, cmax.r, alpha))
               curr.color.g = math.floor(lerp(cmin.g, cmax.g, alpha))
               curr.color.b = math.floor(lerp(cmin.b, cmax.b, alpha))
            end
         end

         if curr.time < m_fOverheadNumberFadeTime and m_fOverheadNumberFadeTime > 0 then
            curr.color.a = math.floor((curr.time / m_fOverheadNumberFadeTime) * 255.0)
         end

         if accu_time < m_fOverheadNumberScaleTime then
            local peak = m_fOverheadNumberScaleTime / 2.0
            if accu_time < peak then
               curr.scale = 1.0 + ((accu_time / peak) * m_fOverheadNumberMaxScaleAmount)
            else
               curr.scale = 1.0 + ((1.0 - ((accu_time - (m_fOverheadNumberScaleTime - peak)) / (m_fOverheadNumberScaleTime - peak))) * m_fOverheadNumberMaxScaleAmount)
            end
         elseif curr.scale ~= 1.0 then
            curr.scale = 1.0
         end

         local loc = Vector(curr.location.x, curr.location.y, curr.location.z)
         if isOnScreen(hud, loc) then
            loc = project(hud, loc)
            loc.z = curr.location.w
            if curr.shieldDamage then
               loc.y = loc.y - 20.0
            end

            curr.scale = curr.scale * damageNumbersScale
            if !curr.number <= 85
               loc.x = loc.x + damageNumbersOffsetX
               loc.y = loc.y + damageNumbersOffsetY
            end
            drawDamageNumber(hud, str, curr.color, loc, curr.scale, curr.scale)
         end
      end
      i = i + 1
   end
end