PICO-8 Wave System

td_wave_system_dummy.p8

pico-8 cartridge // http://www.pico-8.com
version 42
__lua__
-- I would create an enemy adder function that 
-- creates enemies at certain positions (basically spawn them in)
function add_enemy(_x, _y, _type)
    -- if youw ant to store enemy properties, I'd do it here in an array
    -- for ex:
    --[[
    local enemyData = {
        -- hp, speed, droppedGold, timers, powerups, states, animationtime, sprite
         "1,1,3", -- enemy type 1
         "2,2,3" -- enemy type 2
    }
    ]]
    -- split() -- split(string, seperator) -> gives back and array
    -- with the elements that were splitted
    -- local dataForEnemyTypeAdded = split(enemyData[1],",") -- -> {1,1,3}
    -- if you use this then enemy declaration would look like htis
    --[[ 
        local enemy = {
        x = _x,
        y = _y,
        type = _type,
        hp = dataForEnemyTypeAdded[1],
        speed = dataForEnemyTypeAdded[2],
        droppedGold = dataForEnemyTypeAdded[3]
    }
    ]]

    -- if you would store data like below
    -- first enemy would drop 1
    -- second type would drop 2
    -- third would drop
    -- local enemyDroppedGold = {1,2,3}
    -- local enemyHealthData = {10,20,30}


    local enemy = {
        x = _x,
        y = _y,
        type = _type,
        hp = 10 -- we don't use it in the code, but you can
        -- do that for however you want
        -- you would use it like this: goldDropped = enemyDroppedGold[_type]
    }
    add(enemies, enemy)
end


-- this will handle reading in the wave that we want to spawn
-- and setup things to go
function load_level_data(_level)
    -- fetch the wave from the global data strote where we have
    -- all the waves defined already
    -- global_wave_data[level] - is the current level's wave
    -- split it into numbers, which are the types of the enemies
    -- we want to spawn
    current_level_wave = split(global_wave_data[_level], ",")
    currentLevelWon = false
    startNewWave = false
end

-- runs when cart starts
function _init()
    -- collection to store enemies
    enemies = {}
    add_enemy(0,0,1)
    -- have a collection that stores the wave
    -- data for each level
    global_wave_data = {
        "1,2,1",
        "3,3,3"
    }
    -- you can spice this data up, so maybe, each enemy will hold
    -- how much time needs to pass before spawning in the next enemy
    -- so it would be something like:
    -- "id, timeForNext | id2, timeForNext2"
    -- "1, 30 | 1, 20 | ...."
    -- just split the whole thing twice.
    -- for this you will also need a framecounter (or not and live like a rebel)


    -- this holds the lvel we are on
    level = 1
    -- did we won the game
    won = false
    -- the current level's wave data
    current_level_wave = {}
    -- start the first wave
    load_level_data(level)
    -- let's have a boolen to signal
    -- if the current wave is defated
    -- so we can press a button to start the
    -- next one
    currentLevelWon = false
    startNewWave = false
end

function _update()
    -- let's just move them to the left fro
    -- the time being
    for enemy in all(enemies) do
        -- move the enemy 1 pixel per frame
        enemy.x += 1
        -- if it is offscreen delete it
        if (enemy.x > 128) then
            if enemy.type == 3 then
                    -- here you can play with where to spawn
                    -- the enemy, first two numbers are the x,y
                    -- positions
                    add_enemy(0,0,1)
                end
            del(enemies, enemy)
        end

        -- when they die you can do all kinds of things
        if enemy.hp < 0 then
            -- here you can give gold to the player
            -- gold += enemy.goldDropped
            -- you can also do splitting enemies,
            -- just call a new add_enemy() here
            -- with a type check against the enemy
            -- you want to split
            --[[
                if enemy.type == 3 then
                    add_enemy(0,0,1)
                end
            ]]
        end
    end

    -- if we won and press button five, start the next
    -- wave
    if btnp(5) and currentLevelWon then
        -- set the start boolean to true, so in the
        -- empty enemy collection check in won
        -- we can start the next level
        startNewWave = true
    end

    -- define some strategy to spawn enemies
    -- this can be basically anything you want
    -- for now, we want to spawn an enemy every second
    if (time() % 1 == 0) and (#current_level_wave > 0) then
        -- grab the first eenemy from the table to spawn
        -- deli is delete index from table and we can 
        -- save that to spawn it into the game
        local enemyToSpawn = deli(current_level_wave, 1)
        -- add the next enemy to the game
        add_enemy(0, 0, enemyToSpawn)
    end

    -- check if all enemies are dead, if so
    -- load in the new level data. We can do this
    -- by checking if there are no enemies to spawn still inside
    -- our wave data, and all enemies that are spawned are actually dead
    if (#current_level_wave == 0) and (#enemies == 0) then
        -- we won the current level
        -- you can do with this boolean whatever you want to
        -- do
        currentLevelWon = true
        -- if we pressed a button after winning, start a new wave
        if (currentLevelWon and startNewWave) then
            -- once wave is clear
            -- increase the level counter
            level += 1
            -- if we still have a wave left to fight in game
            -- load it in
            if level <= #global_wave_data then
                -- load in the next level's data
                load_level_data(level)
            else
                -- else we won
                won = true
            end
        end
    end
end

function _draw()
    cls()
    for enemy in all(enemies) do
       -- enemy.type is 1,2,3 so I have just dummy enemy sprites
       -- on sprite id 1,2,3
       spr(enemy.type, enemy.x, enemy.y)
    end

    if won then
        print("won",32,32,7)
    end
end
__gfx__
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000770000080880000b0bb0000909900000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
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