BossHealthGui(STORY GAME)

local Humanoid = script:WaitForChild("Humanoid").Value;

local HealthBar = script.Parent:WaitForChild("HealthBar");
local Main = HealthBar:WaitForChild("Main");
local HealthText = HealthBar:WaitForChild("HealthText");
local NameText = script.Parent:WaitForChild("NameText");

local healthBarColors = {
    Color3.fromRGB(0,200,0);
    Color3.fromRGB(200,200,0);
    Color3.fromRGB(200,200/3*2,0);
    Color3.fromRGB(200,0,0);
    Color3.fromRGB(200/3,0,0);
};

local function rangePercentage(input,min,max)
    return ((input-min)*100)/(max-min);
end;

Main.BackgroundColor3 = healthBarColors[1];

local function updateBar(health,maxHealth)
    NameText.Text = Humanoid.DisplayName ~= ""
    and Humanoid.DisplayName or Humanoid.Parent.Name;
    NameText.Text = string.upper(NameText.Text);

    HealthText.Text = string.format("%02i / %02i",health,maxHealth);
    Main.Size = UDim2.new(health/maxHealth,0,1,0);

    if health/maxHealth <= 0.2 then
        local alpha = 1 - rangePercentage(health,0,maxHealth*0.2)/100;
        Main.BackgroundColor3 = healthBarColors[4]:lerp(healthBarColors[5],alpha);
    elseif health/maxHealth <= 1/3 then
        local alpha = 1 - rangePercentage(health,maxHealth*0.2,maxHealth*(1/3))/100;
        Main.BackgroundColor3 = healthBarColors[3]:lerp(healthBarColors[4],alpha);
    elseif health/maxHealth <= 0.5 then
        local alpha = 1 - rangePercentage(health,maxHealth*(1/3),maxHealth*0.5)/100;
        Main.BackgroundColor3 = healthBarColors[2]:lerp(healthBarColors[3],alpha);
    else
        local alpha = 1 - rangePercentage(health,maxHealth*0.5,maxHealth)/100;
        Main.BackgroundColor3 = healthBarColors[1]:lerp(healthBarColors[2],alpha);
    end;
end;

updateBar(Humanoid.Health,Humanoid.MaxHealth);
Humanoid.HealthChanged:Connect(function(health)
    updateBar(health,Humanoid.MaxHealth);
end);