lovexp/asteroids/main.lua

local love = require("love")
local phys = require("phys")
local inspect = require("inspect")

local function initGame()
    return {
        width = 800,
        height = 600,
        ship = {
            radius = 30,
            bullet = {
                radius = 5,
                recoil = 10,
                speed = 500,
                time = 4,
                sound = love.sound.newSoundData('resources/bullet.mp3'),
            },
            sprite = love.graphics.newImage('resources/playerShip1_blue.png'),
        },
        asteroids = {
            stages = {
                { speed = 120, radius = 15, sprite = love.graphics.newImage('resources/meteorBrown_tiny1.png') },
                { speed = 70,  radius = 30, sprite = love.graphics.newImage('resources/meteorBrown_small1.png') },
                { speed = 50,  radius = 50, sprite = love.graphics.newImage('resources/meteorBrown_med1.png') },
                { speed = 20,  radius = 80, sprite = love.graphics.newImage('resources/meteorBrown_big1.png') },
            },
        },
        controls = {
            ship = {
                turnRate = 10,
                maxThrust = 200,
            },
        },
    }
end

-- The constant properties of the game.
local game = initGame()

local function initState()
    local asteroids = {
        {
            x = 100,
            y = 100,
        },
        {
            x = game.width - 100,
            y = 100,
        },
        {
            x = game.width / 2,
            y = game.height - 100,
        }
    }
    for _, asteroid in ipairs(asteroids) do
        asteroid.angle = love.math.random() * phys.tau
        asteroid.stage = #game.asteroids.stages
        local stage = game.asteroids.stages[asteroid.stage]
        asteroid.speed = stage.speed
        asteroid.facing = math.random() * phys.tau
        asteroid.spin = 0.1 + math.random() * 0.1
        asteroid.radius = stage.radius
        asteroid.sprite = stage.sprite
    end
    local joystick = nil
    if love.joystick.getJoystickCount() == 1 then
        joystick = love.joystick.getJoysticks()[1]
    end
    return {
        ship = {
            x = game.width / 2,
            y = game.height / 2,
            angle = 0,
            speed = 0,
            spin = 0,
            facing = phys.tau * 3 / 4,
            radius = game.ship.radius,
        },
        bullets = {},
        asteroids = asteroids,
        controls = {
            joystick = joystick,
        }
    }
end

-- The varying properties of a game being played.
local state = {}

local function reset()
    state = initState()
end

function love.load()
    reset()
end

--  updates the actor's location by applying the passage of time within the game world
local function update(actor, dt)
    phys.update(actor, dt)
    actor.x = actor.x % game.width
    actor.y = actor.y % game.height
end

function love.update(dt)
    if state.controls.joystick ~= nil then
        local thrust = state.controls.joystick:getGamepadAxis('triggerright') * game.controls.ship.maxThrust
        if thrust > 0 then
            phys.apply(state.ship, { speed = thrust * dt, angle = state.ship.facing })
        end

        local spin = state.controls.joystick:getGamepadAxis('leftx') * game.controls.ship.turnRate
        state.ship.facing = (state.ship.facing + spin * dt)
    end
    update(state.ship, dt)

    for bulletIndex = #state.bullets, 1, -1 do
        local bullet = state.bullets[bulletIndex]
        bullet.timeLeft = bullet.timeLeft - dt
        if bullet.timeLeft <= 0 then
            table.remove(state.bullets, bulletIndex)
        else
            update(bullet, dt)
        end
        for asteroidIndex = #state.asteroids, 1, -1 do
            local asteroid = state.asteroids[asteroidIndex]
            if phys.intersects(bullet, asteroid) then
                table.remove(state.bullets, bulletIndex)
                if asteroid.stage > 1 then
                    local angle1 = love.math.random() * phys.tau
                    local angle2 = angle1 - phys.tau / 2
                    local stage = game.asteroids.stages[asteroid.stage - 1]
                    local radius = stage.radius
                    local speed = stage.speed
                    local sprite = stage.sprite
                    table.insert(state.asteroids, {
                        x = asteroid.x,
                        y = asteroid.y,
                        angle = angle1,
                        stage = asteroid.stage - 1,
                        radius = radius,
                        speed = speed,
                        facing = math.random() * phys.tau,
                        spin = 0.1 + math.random() * 0.1,
                        sprite = sprite,
                    })
                    table.insert(state.asteroids, {
                        x = asteroid.x,
                        y = asteroid.y,
                        angle = angle2,
                        stage = asteroid.stage - 1,
                        radius = radius,
                        speed = speed,
                        facing = math.random() * phys.tau,
                        spin = 0.1 + math.random() * 0.1,
                        sprite = sprite,
                    })
                end
                table.remove(state.asteroids, asteroidIndex)
                break
            end
        end
    end

    for _, asteroid in ipairs(state.asteroids) do
        update(asteroid, dt)

        if phys.intersects(state.ship, asteroid) then
            reset()
            break
        end
    end

    if #state.asteroids == 0 then
        reset()
    end
end

function love.gamepadpressed(joystick, button)
    if joystick ~= state.controls.joystick then
        return
    end
    if button == "b" then
        -- debounce, perhaps
        local bullet = {
            x = state.ship.x + math.cos(state.ship.facing) * game.ship.radius,
            y = state.ship.y + math.sin(state.ship.facing) * game.ship.radius,
            angle = state.ship.facing,
            speed = game.ship.bullet.speed,
            radius = game.ship.bullet.radius,
            timeLeft = game.ship.bullet.time,
            sound = love.audio.newSource(game.ship.bullet.sound),
            facing = state.ship.facing,
            spin = 0,
        }
        phys.apply(bullet, state.ship)
        table.insert(state.bullets, bullet)
        bullet.sound:play()
        phys.apply(state.ship, { speed = game.ship.bullet.recoil, angle = state.ship.facing + phys.tau / 2 })
    end
    if button == "x" then
        print(inspect(state.ship))
    end
end

function love.draw()
    for y = -1, 1 do
        for x = -1, 1 do
            love.graphics.origin()
            love.graphics.translate(x * game.width, y * game.height)
            love.graphics.setColor(1, 1, 1)
            local scale = 2 * game.ship.radius / math.max(game.ship.sprite:getWidth(), game.ship.sprite:getHeight())
            love.graphics.draw(game.ship.sprite,
                state.ship.x,
                state.ship.y,
                (state.ship.facing + phys.tau / 4) % phys.tau,
                scale,
                scale,
                game.ship.sprite:getWidth() / 2,
                game.ship.sprite:getHeight() / 2
            )

            for _, bullet in ipairs(state.bullets) do
                love.graphics.setColor(0, 1, 0)
                love.graphics.circle('fill', bullet.x, bullet.y, game.ship.bullet.radius)
            end

            for _, asteroid in ipairs(state.asteroids) do
                love.graphics.setColor(1, 1, 1)
                scale = 2 * asteroid.radius / math.max(asteroid.sprite:getWidth(), asteroid.sprite:getHeight())
                love.graphics.draw(asteroid.sprite,
                    asteroid.x,
                    asteroid.y,
                    asteroid.facing,
                    scale,
                    scale,
                    asteroid.sprite:getWidth() / 2,
                    asteroid.sprite:getHeight() / 2
                )
            end
        end
    end
end