Chopper Command: Adding the Player

Now we add the player sprite to the screen and listen to key events to move the player about. I’ll use löve’s api for the key events. But first, let’s add the player class

player.lua

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local Player = {}
 
 
 
local gameSprite = require("gamesprite")
 
local constants = require ("constants")
 
local Point = require ("point")
 
local Rectangle = require ("rectangle")
 
 
 
 
 
function Player.new (gameModel, boundaries)	
 
 
 
	local sprite = {}
 
 
 
	gameSprite.decorate(sprite, gameModel)
 
 
 
    sprite.screenScroll = 0
 
 
 
	sprite.moveLeft = false
 
	sprite.moveRight = false
 
	sprite.moveUp = false
 
	sprite.moveDown = false
 
 
 
	sprite._nextPosition = Point.new(0,0)
 
	sprite._vector = Point.new(0,0)
 
 
 
	sprite._minX = boundaries.x
 
	sprite._maxX = boundaries.right
 
	sprite._minY = boundaries.y
 
	sprite._maxY = boundaries.bottom
 
	sprite._range = boundaries.width * 0.35
 
 
 
	sprite._acceleration = Point.new(0.5,4)
 
	sprite._maxSpeed = 20.0
 
 
 
	sprite._transition = 0.0
 
	sprite._screenScrollNow = 0.0
 
	sprite._screenScrollTarget = 0.0
 
 
 
	sprite._boom = love.graphics.newImage ( "sprites/boom1.png" )
 
 
 
    --radarSkin = new RadarPlayerSkin()
 
 
 
 
 
	function sprite:reset (type)
 
 
 
		self.scaleX = 1
 
 
 
		self.x = self._minX
 
		self.y = self._minY + (self._maxY - self._minY) * 0.5
 
 
 
		self._nextPosition = Point.new(self.x, self.y)
 
		self._vector = Point.new(0,0)
 
 
 
		local frame1 = love.graphics.newImage ( "sprites/player1.png" )
 
		local frame2 = love.graphics.newImage ( "sprites/player2.png" )
 
 
 
		self.animationFrames = { frame1, frame2 }
 
 
 
		self.skin = sprite.animationFrames[1]
 
 
 
		self.width = self.skin:getWidth()
 
		self.height = self.skin:getHeight()
 
 
 
		self.halfWidth = self.width * 0.5
 
		self.halfHeight = self.height * 0.5
 
		self.squaredRadius = math.pow(self.height * 0.5, 2)
 
 
 
		self.visible = true
 
		self.active = true
 
		self.alpha = 1
 
 
 
 
 
	end
 
 
 
 
 
	function sprite:update (dt)
 
 
 
		if visible == false then
 
			return 
 
		end 
 
 
 
		if  self.active == false then
 
			return
 
		end
 
 
 
		self:animate(dt)
 
 
 
		--handle up and down movement (easy peasy)
 
		self._vector.y = 0
 
 
 
		if self.moveUp == true then
 
			self._vector.y = - self._acceleration.y
 
		elseif self.moveDown == true then
 
			self._vector.y = self._acceleration.y
 
		end
 
		self._nextPosition.y = self._nextPosition.y + self._vector.y
 
 
 
 
 
		if self._nextPosition.y < self._minY then
 
			self._nextPosition.y = self._minY
 
		end
 
		if self._nextPosition.y > self._maxY then
 
			self._nextPosition.y = self._maxY
 
		end
 
 
 
 
 
		--handle flip
 
		if self.scaleX > 0 and self.moveLeft == true then
 
			self.scaleX = -1
 
		end
 
 
 
		if self.scaleX < 0 and self.moveRight == true then
 
			self.scaleX = 1
 
		end
 
 
 
 
 
		--if player is inside update region
 
		if  (self.scaleX > 0 and self.x <= self._minX + self._range) 
 
		or (self.scaleX < 0 and self.x >= self._maxX - self._range ) then
 
 
 
 
 
			if self.moveRight == true or self.moveLeft == true then
 
				self._vector.x =  self._vector.x + self._acceleration.x
 
			else
 
				self._vector.x =  -  self._acceleration.x * 16
 
			end
 
 
 
			if self.scaleX > 0 then
 
				self._screenScrollTarget = self._maxSpeed * ((self.x - self._minX)/(self._minX + self._range)) * -1
 
			end
 
 
 
			if self.scaleX < 0 then
 
				self._screenScrollTarget = self._maxSpeed * ((self._maxX - self.x )/(self._minX + self._range))
 
			end
 
		else
 
			--player is flipping
 
			self._vector.x =  -  self._acceleration.x * 16
 
 
 
			if self._screenScrollTarget ~= self._vector.x * self.scaleX then
 
				self._transition = 0
 
				self._screenScrollTarget = self._vector.x * self.scaleX
 
			end
 
		end
 
 
 
		if self._vector.x > self._maxSpeed then
 
			self._vector.x = self._maxSpeed
 
		end
 
 
 
		if self._vector.x <  - self._maxSpeed then
 
			self._vector.x =  - self._maxSpeed
 
		end
 
 
 
		self._nextPosition.x =  self._nextPosition.x + self._vector.x * self.scaleX
 
 
 
		if self.scaleX > 0 and self.x <= self._minX + self._range then
 
 
 
			if self._nextPosition.x >= self._minX + self._range then
 
				self._nextPosition.x = self._minX + self._range
 
			end
 
		end
 
 
 
		if self.scaleX < 0 and self.x >= self._maxX - self._range then
 
			if self._nextPosition.x <= self._maxX - self._range then
 
				self._nextPosition.x = self._maxX - self._range
 
			end
 
		end
 
 
 
		if self._nextPosition.x < self._minX then
 
			self._nextPosition.x = self._minX
 
		end
 
 
 
		if self._nextPosition.x > self._maxX then
 
			self._nextPosition.x = self._maxX
 
		end
 
 
 
 
 
		self.x = self._nextPosition.x
 
		self.y = self._nextPosition.y
 
 
 
		self:updateScreenSpeed ()
 
 
 
	end
 
 
 
	function sprite:hit ()
 
 
 
		if self.active == true then
 
			self.active = false
 
			self.gameModel.running = false
 
			--self.skin = _boom
 
		end
 
	end
 
 
 
	function sprite:setPositionX ( value )
 
		self.x = value
 
		self._nextPosition.x = value
 
	end
 
 
 
	function sprite:setPositionY ( value )
 
		self.y = value
 
		self._nextPosition.y = value
 
	end
 
 
 
	function sprite:setPosition ( valueX, valueY )
 
		self.x = valueX
 
		self._nextPosition.x = valueX
 
		self.y = valueY
 
		self._nextPosition.y = valueY
 
	end
 
 
 
	function sprite:updateScreenSpeed ()
 
 
 
		if self._screenScrollNow ~= self._screenScrollTarget then
 
			self._screenScrollNow = self._screenScrollNow + (self._screenScrollTarget - self._screenScrollNow) * self._transition
 
			self._transition =  self._transition + 0.01
 
 
 
			self.screenScroll = self._screenScrollNow
 
		end
 
 
 
		if self._transition > 1 then
 
			self._transition = 0
 
		end
 
 
 
	end
 
 
 
	sprite:reset ( RESET_HARD )
 
 
 
 
 
	return sprite
 
end
 
 
 
return Player

Just as I’ve done with the previous version, I need to update the moveLeft, moveRight, moveUp and moveDown booleans based on keys pressed. (Later I’ll have to change this to a on screen pad controller, similar to the one I used in the Frogger game.)

So in main.lua I instantiate the player, and add it to update and draw. But this time I also add a queryKeys function call inside the update

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-- in main.lua, inside the init method
 
player = Player.new ( gameModel, Rectangle.new (50, 0, constants.SCREEN_WIDTH - 100, constants.SCREEN_HEIGHT) )
 
 
 
-- then
 
-- update game
 
function love.update (dt)
 
 
 
	queryKeys()
 
 
 
	truck1:update(dt)
 
	truck2:update(dt)
 
	truck3:update(dt)
 
	enemy1:update(dt)
 
	enemy2:update(dt)
 
	enemy3:update(dt)
 
	player:update(dt)
 
 
 
end
 
 
 
 
 
-- draw everything
 
function love.draw()
 
 
 
	love.graphics.draw(canvas_bg)
 
	truck1:draw()
 
	truck2:draw()
 
	truck3:draw()
 
	enemy1:draw()
 
	enemy2:draw()
 
	enemy3:draw()
 
	player:draw()
 
end
 
 
 
function queryKeys ()
 
 
 
	player.moveLeft = love.keyboard.isDown( "left" )
 
	player.moveRight = love.keyboard.isDown( "right" )
 
	player.moveUp = love.keyboard.isDown( "up" )
 
	player.moveDown = love.keyboard.isDown( "down" )
 
	player.moveDown = love.keyboard.isDown( "down" )
 
	--shooting = love.keyboard.isDown( "space" )
 
 
 
end

I’ll add shooting next. But this is all we need in order to control the sprite. Pretty neat.

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