Tuto tiny-ecs 2d platformer Part 7 Enemies

Enemies

The next entities we are going to create: the enemies.

As I have mentioned before, components are shared amongst entities and this is exactly the case here. The enemies share the same components as our player1. The structure of an enemy Entity is almost the same as the player1 Entity.

eGroundNmes.lua

Please create a file "eGroundNmes.lua" in the "_E" folder and the code:

EGroundNmes = Core.class()

function EGroundNmes:init(xid, xspritelayer, xpos, xbgfxlayer, xcollectible)
	-- ids
	self.isnme = true
	self.eid = xid
	self.ispersistent = false -- keep sprite visible when dead
	-- sprite layers
	self.spritelayer = xspritelayer
	self.bgfxlayer = xbgfxlayer
	-- actor holds a collectible?
	if xcollectible then
		self.collectible = xcollectible
	end
	-- params
	self.pos = xpos
	self.sx = 1 -- 0.96
	self.sy = self.sx
	self.totallives = 1 -- basic nme
	self.totalhealth = 3 -- basic nme
	-- 100: no move, no jump, shoot straight, you choose the nme abilities!
	-- 200: move, jump, no shoot, you choose the nme abilities!
	-- 300: no move, no jump, shoot all angles, shield, you choose the nme abilities!
	if self.eid == 200 then
		self.ispersistent = true -- keep sprite visible on dead
		self.totallives = 2
		self.totalhealth = 3
	end
	-- recovery
	self.recovertimer = 10
	self.recoverbadtimer = 30
	self.actiontimer = 90 -- 60, math.random(32, 96), low value=hard, high value=easy
	if g_difficulty == 0 then -- easy
		self.totallives = 1
		self.totalhealth = 3
		self.recovertimer *= 0.5
		self.recoverbadtimer *= 0.5
		self.actiontimer *= 2
	elseif g_difficulty == 2 then -- hard
		self.recovertimer *= 2
		self.recoverbadtimer *= 2
		self.actiontimer *= 0.5
	end
	self.hitfx = Bitmap.new(Texture.new("gfx/fxs/1.png"))
	self.hitfx:setAnchorPoint(0.5, 0.5)
	-- COMPONENTS
	-- ANIMATION
	local anims = {} -- table to hold actor animations
	local animsimgs = {} -- table to hold actor animations images
	-- CAnimation:init(xanimspeed)
	local framerate = 1/10 -- 1/12
	self.animation = CAnimation.new(framerate)
	-- CAnimation:cutSpritesheet(xspritesheetpath, xcols, xrows, xanimsimgs, xoffx, xoffy, sx, sy)
	local texpath
	local cols, rows
	if self.eid == 100 then
		texpath = "gfx/nmes/Zombie_0020.png"
		cols, rows = 4, 4
		self.animation:cutSpritesheet(texpath, cols, rows, animsimgs, 0, 1, self.sx, self.sy)
	elseif self.eid == 200 then
		texpath = "gfx/nmes/Zombie_0040.png"
		cols, rows = 3, 3
		self.animation:cutSpritesheet(texpath, cols, rows, animsimgs, 0, 1, self.sx, self.sy)
	elseif self.eid == 300 then
		texpath = "gfx/nmes/Zombie_0001.png"
		cols, rows = 5, 3
		self.animation:cutSpritesheet(texpath, cols, rows, animsimgs, 0, 1, self.sx, self.sy)
	end
	-- 1st set of animations: CAnimation:createAnim(xanims, xanimname, xanimsimgs, xtable, xstart, xfinish)
	if self.eid == 100 then
		self.animation:createAnim(anims, g_ANIM_DEFAULT, animsimgs, nil, 1, cols*rows)
		self.animation:createAnim(anims, g_ANIM_IDLE_R, animsimgs, nil, 1, cols*rows) -- fluid is best
	elseif self.eid == 200 then
		self.animation:createAnim(anims, g_ANIM_DEFAULT, animsimgs, nil, 1, cols*rows)
		self.animation:createAnim(anims, g_ANIM_IDLE_R, animsimgs, nil, 1, cols*rows) -- fluid is best
		self.animation:createAnim(anims, g_ANIM_RUN_R, animsimgs, nil, 1, cols*rows) -- fluid is best
	elseif self.eid == 300 then
		self.animation:createAnim(anims, g_ANIM_DEFAULT, animsimgs, nil, 5, 5)
		self.animation:createAnim(anims, g_ANIM_IDLE_R, animsimgs, nil, 5, 5) -- fluid is best
	end
	-- end animations
	self.animation.anims = anims
	self.sprite = self.animation.sprite
	self.animation.sprite = nil -- free some memory
	self.w, self.h = self.sprite:getWidth(), self.sprite:getHeight() -- with applied scale
	-- BODY: CBody:init(xmass, xspeed, xupspeed, xextra)
	if self.eid == 100 then
		self.body = CBody.new(1, 0, 0, true)
	elseif self.eid == 200 then
		self.body = CBody.new(1, 12*8, 64*8, true)
	elseif self.eid == 300 then
		self.body = CBody.new(1, 0, 0, true)
	end
	-- COLLISION BOX: CCollisionBox:init(xcollwidth, xcollheight)
	local collw, collh = (self.w*0.5)//1, (self.h*0.8)//1 -- must be round numbers for cbump physics!
	self.collbox = CCollisionBox.new(collw, collh)
	-- AI
	self.ai = true
	-- shield
	self.shield = {}
	self.shield.sprite = Pixel.new(0x5555ff, 0.75, 8, collh-6)
	self.shield.sprite.sx = 1
	self.shield.sprite.sy = self.shield.sprite.sx
	self.shield.sprite:setScale(self.shield.sprite.sx, self.shield.sprite.sy)
	self.shield.sprite:setAnchorPoint(0.5, 0.5)
	self.spritelayer:addChild(self.shield.sprite)
	self.shield.offset = vector(collw, (collh+6)*0.5)
	self.shield.timer = 4*8 -- 4*8, 2*8
	self.shield.currtimer = self.shield.timer
	self.shield.damage = 0.1
end

This is almost exactly the same code as the player1, there are three main differences:

• some variables were moved to the enemy System, this makes the code for our enemies shorter
• we adjust the enemy parameters based on the difficulty of the game and the Entity id (eid)
• we have an extra Component: the AI Component

note: I only add ground enemies, feel free to create your own when you have finished the tutorial ;-)

AI

In order for the enemies to attack the player, we give them an artificial intelligence ability. This Component is only given a name (self.ai), there is no code to it!

The AI System will filter the entities based on that name. In the AI System our enemies will have different behaviors like movements and attacks.

Next?

Before tackling all the systems that will tie our game together, we will create some more entities for our game: moving platforms, doors, collectibles, ...

Prev.: Tuto tiny-ecs 2d platformer Part 6 ECS Components
Next: Tuto tiny-ecs 2d platformer Part 8 more entities

Tutorial - tiny-ecs 2d platformer

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