dude.lua

scr_x, scr_y = term.getSize()

local dude = {
    x = scr_x / 2,
    y = scr_y / 2,
    oldx = scr_x / 2,
    oldy = scr_y / 2,
    xvel = 0,
    yvel = 0,
    speed = 0.6,
    friction = 1.5,

    bullets = {},
    bulletSpeed = 1
}

local tick = function(dude)
    dude.oldx = dude.x
    dude.oldy = dude.y
    dude.x = dude.x + dude.xvel
    dude.y = dude.y + dude.yvel
    dude.xvel = dude.xvel / dude.friction
    dude.yvel = dude.yvel / dude.friction
    local rList = {}
    for i = 1, #dude.bullets do
        if not (inRange(dude.bullets[i].x, 1, scr_x + 1) and inRange(dude.bullets[i].y, 1, scr_y + 1)) then
            if dude.bullets[i].offScreen == false then
                rList[#rList + 1] = i
            end
        else
            dude.bullets[i].offScreen = false
        end
        dude.bullets[i].oldx = dude.bullets[i].x
        dude.bullets[i].oldy = dude.bullets[i].y
        dude.bullets[i].x = dude.bullets[i].x + dude.bullets[i].xvel
        dude.bullets[i].y = dude.bullets[i].y + dude.bullets[i].yvel
        dude.bullets[i].xvel = dude.bullets[i].xvel / dude.bullets[i].friction
        dude.bullets[i].yvel = dude.bullets[i].yvel / dude.bullets[i].friction
    end
    for i = #rList, 1, -1 do
        table.remove(dude.bullets, rList[i])
    end
end

local render = function()
    if (math.floor(dude.oldx) ~= math.floor(dude.x)) or (math.floor(dude.oldy) ~= math.floor(dude.y)) then
        term.setCursorPos(dude.oldx, dude.oldy)
        term.write(" ")
    end
    term.setCursorPos(dude.x, dude.y)
    term.write("O")
    for i = 1, #dude.bullets do
        if (math.floor(dude.bullets[i].oldx) ~= math.floor(dude.bullets[i].x)) or (math.floor(dude.bullets[i].oldy) ~= math.floor(dude.bullets[i].y)) then
            term.setCursorPos(dude.bullets[i].oldx, dude.bullets[i].oldy)
            term.write(" ")
        end
        term.setCursorPos(dude.bullets[i].x, dude.bullets[i].y)
        term.write("x")
    end
end

local spawnBullet = function(dude, xMult, yMult)
    table.insert(dude.bullets, {
        x = dude.x,
        y = dude.y,
        oldx = dude.oldx,
        oldy = dude.oldy,
        xvel = dude.bulletSpeed * xMult,
        yvel = dude.bulletSpeed * yMult,
        offScreen = not (inRange(dude.x, 1, scr_x + 1) and inRange(dude.y, 1, scr_y + 1)),
        friction = 1
    })
end

inRange = function(num, min, max)
    return num >= min and num <= max
end

local tickTimer = os.startTimer(0.05)
local keysDown = {}
local evt
term.clear()
while true do
    evt = {os.pullEvent()}
    if evt[1] == "key" and not evt[3] then
        keysDown[evt[2]] = 0
    elseif evt[1] == "key_up" then
        keysDown[evt[2]] = nil
    elseif evt[1] == "timer" and evt[2] == tickTimer then
        tick(dude)
        tickTimer = os.startTimer(0.05)

        if keysDown[keys.w] then
            dude.yvel = dude.yvel - dude.speed
        end
        if keysDown[keys.s] then
            dude.yvel = dude.yvel + dude.speed
        end
        if keysDown[keys.a] then
            dude.xvel = dude.xvel - dude.speed
        end
        if keysDown[keys.d] then
            dude.xvel = dude.xvel + dude.speed
        end

        if keysDown[keys.up] == 0 then
            spawnBullet(dude, 0, -1)
        end
        if keysDown[keys.down] == 0 then
            spawnBullet(dude, 0, 1)
        end
        if keysDown[keys.left] == 0 then
            spawnBullet(dude, -1, 0)
        end
        if keysDown[keys.right] == 0 then
            spawnBullet(dude, 1, 0)
        end

        for k,v in pairs(keysDown) do
            keysDown[k] = v + 1
        end

        render()
    end
end