Ground Slam

Lesson 9 of 20 in Coddy's Roblox Game: Battlegrounds course.

A second ability, on E: a ground slam that hits everyone around you and throws them away. workspace:GetPartBoundsInRadius(position, radius, params) finds the parts within a distance, and ApplyImpulse on a root gives its whole body a push. An impulse is a change of speed times mass, so multiplying by AssemblyMass throws light and heavy rigs the same way:

theirRoot:ApplyImpulse((away * Settings.SlamKnockback + Vector3.new(0, 40, 0)) * theirRoot.AssemblyMass)

Now the game has two ways to hurt someone, and more are coming. Every hit goes through one function, hurt(humanoid, amount), so a rule about damage (blocking, next lesson) is written once.

Challenge

Medium

Write hurt(humanoid, amount) above swing: return if the Humanoid is already beaten, otherwise TakeDamage(amount). Make swing call it.
Add abilities.Slam: everyone (once each, not you) with a root within Settings.SlamRadius takes Settings.SlamDamage through hurt, and is pushed away from you with Settings.SlamKnockback and 40 up.
In BattleClient, bind "Slam" to E, and add it to the cooldown display.

Press Play, then Check.

Try it yourself

local Players = game:GetService("Players")
local ServerStorage = game:GetService("ServerStorage")
local Settings = require(game.ReplicatedStorage.Settings)

local remotes = game.ReplicatedStorage.Remotes
local lastSwing = {} -- player -> when they last swung

-- Roblox's own sword animations
local slash = Instance.new("Animation")
slash.AnimationId = "rbxassetid://522635514"

print("Swords deal " .. Settings.SwordDamage .. " damage")

-- A swing: the animation, then everyone in the box in front of you is hit
local function swing(player)
	local character = player.Character
	local root = character and character:FindFirstChild("HumanoidRootPart")
	if not root or character.Humanoid.Health <= 0 then
		return
	end
	local now = time()
	if lastSwing[player] and now - lastSwing[player] < Settings.SwingCooldown then
		return
	end
	lastSwing[player] = now
	character.Humanoid.Animator:LoadAnimation(slash):Play()
	-- the box in front of you, never your own body
	local params = OverlapParams.new()
	params.FilterDescendantsInstances = { character }
	local box = root.CFrame * CFrame.new(0, 0, -3)
	local hit = {} -- each humanoid once per swing
	for _, part in workspace:GetPartBoundsInBox(box, Settings.HitboxSize, params) do
		local humanoid = part.Parent:FindFirstChildOfClass("Humanoid")
		if humanoid and not hit[humanoid] then
			hit[humanoid] = true
			humanoid:TakeDamage(Settings.SwordDamage)
		end
	end
end

-- The abilities, by name: what each one does
local abilities = {}

function abilities.Dash(player, character, root)
	root.AssemblyLinearVelocity = root.CFrame.LookVector * Settings.DashSpeed + Vector3.new(0, 15, 0)
end

-- The client asks for an ability by name. The server checks it: a real
-- ability, a living player, and its cooldown over. When it is ready again
-- is an attribute of the player, so their screen can show it.
remotes.Ability.OnServerEvent:Connect(function(player, name)
	if typeof(name) ~= "string" or not abilities[name] then
		return
	end
	local character = player.Character
	local root = character and character:FindFirstChild("HumanoidRootPart")
	if not root or character.Humanoid.Health <= 0 then
		return
	end
	local now = workspace:GetServerTimeNow()
	if now < (player:GetAttribute(name .. "ReadyAt") or 0) then
		return
	end
	player:SetAttribute(name .. "ReadyAt", now + Settings.Cooldowns[name])
	abilities[name](player, character, root)
end)

-- Every player gets Kills on the leaderboard, and a sword every life
Players.PlayerAdded:Connect(function(player)
	local leaderstats = Instance.new("Folder")
	leaderstats.Name = "leaderstats"
	leaderstats.Parent = player

	local kills = Instance.new("IntValue")
	kills.Name = "Kills"
	kills.Parent = leaderstats

	player.CharacterAdded:Connect(function()
		local sword = ServerStorage.Sword:Clone()
		sword.Parent = player.Backpack
		sword.Activated:Connect(function()
			swing(player)
		end)
	end)
end)

-- The training dummy: its health bar follows its health, and a beaten
-- dummy comes back after a moment, a fresh copy in the same place
local function setupDummy(dummy)
	local humanoid = dummy.Humanoid
	humanoid.HealthChanged:Connect(function(health)
		dummy.HealthBar.Back.Fill.Size = UDim2.fromScale(health / humanoid.MaxHealth, 1)
	end)
	humanoid.Died:Connect(function()
		local spot = dummy:GetPivot()
		task.wait(0.5)
		dummy:Destroy()
		task.wait(Settings.DummyRespawn)
		local fresh = ServerStorage.Dummy:Clone()
		fresh:PivotTo(spot)
		fresh.Parent = workspace
		setupDummy(fresh)
	end)
end
setupDummy(workspace.Dummy)