Love2d asteroids (pseudo 3d)

main.lua

local function Vector2(x, y)
	local v = {
		x = x,
		y = y
	}

	return v;
end

local function Mat2( m11, m12, m21, m22 )
	local m = {
		m11 = m11, m12 = m12,
		m21 = m21, m22 = m22
	}

	return m
end

local function Vec2MulMat2( v, m )
	local r = {
		x = m.m11 * v.x + m.m12 * v.y,
		y = m.m21 * v.x + m.m22 * v.y
	}

	return r
end

local function Centroid( poly )
	local x = 0
	local y = 0

	for i,v in ipairs(poly) do
		x = x + v.x
		y = y + v.y
	end

	local v = {
		x = x / #poly,
		y = y / #poly
	}

	return v
end

local function CalcRectForPoly( p, x, y )
	local rect = {
		x = 0,
		y = 0,
		x2 = 0,
		y2 = 0
	}

	for i, v in ipairs(p) do
		if v.x < rect.x then
			rect.x = v.x
		end

		if v.y < rect.y then
			rect.y = v.y
		end

		if v.x > rect.x2 then
			rect.x2 = v.x
		end

		if v.y > rect.y2 then
			rect.y2 = v.y
		end
	end

	rect.x = rect.x + x
	rect.y = rect.y + y
	rect.x2 = rect.x2 + x
	rect.y2 = rect.y2 + y

	return rect
end

local function PointInRect( p, r )
	return (p.x > r.x and p.x < r.x2 and p.y > r.y and p.y < r.y2)
end

-- HELPER FUNCTIONS

function lerp(a, b, t)
	return a + (b - a) * t
end

function ilerp(a, b, t)
	return a - (b + a) * t
end

-- END

-- LOAD RESOURCES

local shootSound = love.audio.newSource("Assets/Sound/shoot1.wav", 'static')
local blowSound = love.audio.newSource("Assets/Sound/blow.wav", 'static')
local ainsSoundData = love.sound.newSoundData("Assets/Sound/asteroid is near the ship.wav")
local ainsSound = love.audio.newSource(ainsSoundData)

-- END

local screenWidth
local screenHeight
local screenWidth2
local screenHeight2

local windowWidth
local windowHeight
local windowWidth2
local windowHeight2

local warningSoundVol = 0

function love.load()
	screenWidth  = love.graphics.getWidth()
	screenHeight = love.graphics.getHeight()
	screenWidth2 = screenWidth / 2
	screenHeight2 = screenHeight / 2

	windowWidth = screenWidth / 1.2
	windowHeight = screenHeight / 1.5
	windowWidth2 = windowWidth / 2
	windowHeight2 = windowHeight / 2

	love.mouse.setVisible( false )

	ainsSound:setVolume(warningSoundVol)
	ainsSound:setLooping(true)
	ainsSound:play()

	shootSound:setVolume(0.5)
	blowSound:setVolume(0.5)
end

local zFar = 100
local bSpeed = 2
local bSize = 50
local shootRate = 60/122
local spawnRate = 1

local modX = 0
local modY = 0

local BulletList = { }

local function ShootBullet( x, y, sx, sy )
	local bullet = {
		ex = x,
		ey = y,
		x = sx + bSize,
		y = sy + bSize,
		z = 0,
		r = bSize
	}

	table.insert(BulletList, bullet)

	shootSound:play()
end

local function DrawBullet( b )
	love.graphics.circle('fill', b.x, b.y, b.r)
end

local function UpdateBullet( i, b, dt )
	b.ex = lerp(b.ex, b.ex - modX, dt * bSpeed)
	b.ey = lerp(b.ey, b.ey - modY, dt * bSpeed)
	b.x = lerp(b.x, b.ex - modX, dt * bSpeed)
	b.y = lerp(b.y, b.ey - modY, dt * bSpeed)
	b.z = lerp(b.z, zFar, dt * bSpeed * 0.5)

	if b.r <= 1 then
		table.remove(BulletList, i)
	else
		b.r = lerp(b.r, 0, dt * bSpeed * 1.5)
	end
end

local AsteroidList = { }

local function SpawnAsteroid()
	local x = love.math.random( 100, screenWidth - 100 )
	local y = love.math.random( 100, screenHeight - 100 )

	local a = {
		x = x,
		y = y,
		z = zFar,
		size = 1,
		--oldsize = 1,
		poly = {
			Vector2(0, 0),
			Vector2(5, 5),
			Vector2(10, 1),
			Vector2(13, -10),
			Vector2(4, -10),
			Vector2(5, -5)
		},
		rect = {
			x = 0,
			y = 0,
			x2 = 0,
			y2 = 0
		}
	}

	table.insert(AsteroidList, a)
end

local function DrawAsteroid( a )
	local poly = { }

	for i,v in ipairs(a.poly) do
		table.insert(poly, v.x + a.x)
		table.insert(poly, v.y + a.y)
	end

	love.graphics.polygon('line', poly)
	--[[love.graphics.polygon('line', a.rect.x, a.rect.y,
								  a.rect.x, a.rect.y2,
								  a.rect.x2, a.rect.y2,
								  a.rect.x2, a.rect.y)]]


end

local function UpdateAsteroid( i, a, dt )
	--a.z = lerp(a.z, zFar, dt * 0.0001)
	a.z = a.z - dt * 8
	a.size = lerp(a.size, 10, dt * 0.0001)
	a.x = a.x - modX * 0.1
	a.y = a.y - modY * 0.1

	if a.z <= 2 then
		if (a.x < 0 and a.y < 0) or (a.x > screenWidth and a.y > screenHeight) then
			table.remove(AsteroidList, i)
			return
		end
		-- Game over
		table.remove(AsteroidList, i)
		return
	end

	local smat = Mat2(a.size, 0,
					  0, a.size)

	local centroid = Centroid(a.poly)

	for i,v in ipairs(a.poly) do
		local x = v.x - centroid.x
		local y = v.y - centroid.y

		local vec = Vec2MulMat2(Vector2(x, y), smat)

		a.poly[i].x = vec.x --+ v.x -- modX
		a.poly[i].y = vec.y --+ v.y -- modY
	end

	a.rect = CalcRectForPoly(a.poly, a.x, a.y)
end

local function CheckCollisions()
	for i,v in ipairs(AsteroidList) do
		for i2,v2 in ipairs(BulletList) do
			if PointInRect({x = v2.x, y = v2.y}, v.rect) and v2.z > v.z then
				table.remove(AsteroidList, i)
				table.remove(BulletList, i2)
				blowSound:play()
			end
		end
	end
end

local prevSTime = 0
local prevATime = 0

local changeVol = false

function love.update(dt)
	local x, y = love.mouse.getPosition()

	modX = lerp(modX, x - screenWidth2, dt * 2)
	modY = lerp(modY, y - screenHeight2, dt * 2)

	if love.mouse.isDown(1) then
		if prevSTime >= shootRate then
			ShootBullet(x, y, 0, windowHeight2)
			ShootBullet(x, y, windowWidth, windowHeight2)
			prevSTime = 0
		end
	end

	if prevATime >= spawnRate then
		SpawnAsteroid()
		prevATime = 0
	end

	-- Collisions
	CheckCollisions()

	-- Bullets
	for k,v in pairs(BulletList) do
		UpdateBullet(k, v, dt)
	end

	-- Asteroids
	for k,v in pairs(AsteroidList) do
		UpdateAsteroid(k, v, dt)

		if v.z < zFar / 2 then
			changeVol = true
		end
	end

	if changeVol then
		warningSoundVol = lerp(warningSoundVol, 0.5, dt * 0.5)
	else
		warningSoundVol = 0
	end

	ainsSound:setVolume(warningSoundVol)

	prevSTime = prevSTime + dt
	prevATime = prevATime + dt
end

function love.draw()
	-- Asteroids
	love.graphics.setColor(200, 200, 255, 255)
	love.graphics.setLineWidth( 2 )

	for i,v in ipairs(AsteroidList) do
		DrawAsteroid(v)
	end

	love.graphics.setLineWidth( 1 )
	love.graphics.setColor(255, 50, 50, 255)

	-- Bullets
	for i,v in ipairs(BulletList) do
		DrawBullet(v)
	end

	love.graphics.setColor(255, 255, 255, 255)

	love.graphics.line(0, 0,
					   screenWidth2 + modX - windowWidth2, screenHeight2 + modY - windowHeight2)
	love.graphics.line(0, 0,
					   screenWidth2 + modX + windowWidth2, screenHeight2 + modY - windowHeight2)
	love.graphics.line(screenWidth2, 0,
					   screenWidth2 + modX, screenHeight2 + modY - windowHeight2)
	love.graphics.line(screenWidth, 0,
					   screenWidth2 + modX + windowWidth2, screenHeight2 + modY - windowHeight2)
	love.graphics.line(screenWidth, 0,
					   screenWidth2 + modX - windowWidth2, screenHeight2 + modY - windowHeight2)
	love.graphics.line(screenWidth + 100, screenHeight2,
					   screenWidth2 + modX + windowWidth2, screenHeight2 + modY)
	love.graphics.line(screenWidth2 - windowWidth2 + modX, screenHeight2 - windowHeight2 + modY,
					   screenWidth2 - windowWidth2 / 2 + modX, screenHeight2 - windowHeight2 / 2 + modY)
	love.graphics.line(screenWidth2 + windowWidth2 + modX, screenHeight2 - windowHeight2 + modY,
					   screenWidth2 + windowWidth2 / 2 + modX, screenHeight2 - windowHeight2 / 2 + modY)

	love.graphics.line(screenWidth, screenHeight,
					   screenWidth2 + modX + windowWidth2, screenHeight2 + modY + windowHeight2)
	love.graphics.line(screenWidth2, screenHeight,
					   screenWidth2 + modX, screenHeight2 + modY + windowHeight2)
	love.graphics.line(0, screenHeight,
					   screenWidth2 + modX + windowWidth2, screenHeight2 + modY + windowHeight2)
	love.graphics.line(-100, screenHeight2,
					   screenWidth2 + modX - windowWidth2, screenHeight2 + modY)
	love.graphics.line(0, screenHeight,
					   screenWidth2 - windowWidth2 + modX, screenHeight2 + windowHeight2 + modY)
	love.graphics.line(screenWidth, screenHeight,
					   screenWidth2 - windowWidth2 + modX, screenHeight2 + windowHeight2 + modY)
	love.graphics.line(screenWidth2 - windowWidth2 + modX, screenHeight2 + windowHeight2 + modY,
					   screenWidth2 - windowWidth2 / 2 + modX, screenHeight2 + windowHeight2 / 2 + modY)
	love.graphics.line(screenWidth2 + windowWidth2 + modX, screenHeight2 + windowHeight2 + modY,
					   screenWidth2 + windowWidth2 / 2 + modX, screenHeight2 + windowHeight2 / 2 + modY)

	-- Center window

	love.graphics.line(screenWidth2 + modX, screenHeight2 - windowHeight2 + modY,
					   screenWidth2 + windowWidth2 + modX, screenHeight2 + modY)
	love.graphics.line(screenWidth2 + windowWidth2 + modX, screenHeight2 + modY,
					   screenWidth2 + modX, screenHeight2 + windowHeight2 + modY)
	love.graphics.line(screenWidth2 + modX, screenHeight2 + windowHeight2 + modY,
					   screenWidth2 - windowWidth2 + modX, screenHeight2 + modY)
	love.graphics.line(screenWidth2 - windowWidth2 + modX, screenHeight2 + modY,
					   screenWidth2 + modX, screenHeight2 - windowHeight2 + modY)

	love.graphics.setColor(255, 255, 255, 50)

	local vertices = {
						0, 0,
						screenWidth2, 0,
						screenWidth2 + modX, screenHeight2 - windowHeight2 + modY,
						screenWidth2 - windowWidth2 + modX, screenHeight2 - windowHeight2 + modY
					 }

	--love.graphics.polygon('fill', vertices)

	local vertices = {
						screenWidth, 0,
						screenWidth2 + windowWidth2 + modX, screenHeight2 - windowHeight2 + modY,
						screenWidth2 + modX, screenHeight2 - windowHeight2 + modY,
						screenWidth2, 0
					 }

	--love.graphics.polygon('fill', vertices)

	love.graphics.setColor(255, 255, 255, 255)

	-- Crosshair
	love.graphics.line(screenWidth2 - 10 + modX, screenHeight2 - 5 + modY,
					   screenWidth2 + 10 + modX, screenHeight2 - 5 + modY)
	love.graphics.line(screenWidth2 - 2 + modX, screenHeight2 + modY,
					   screenWidth2 + 2 + modX, screenHeight2 + modY)
	love.graphics.line(screenWidth2 - 5 + modX, screenHeight2 + 5 + modY,
					   screenWidth2 + 5 + modX, screenHeight2 + 5 + modY)
	love.graphics.line(screenWidth2 + modX, screenHeight2 + modY,
					   screenWidth2 + windowWidth2 + modX, screenHeight2 + modY)

	-- FPS
	love.graphics.print(tostring(love.timer.getFPS()), 10, 10)
end