Roguelike Tutorial, using python3+tdl, part 9 code
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This is part of a series of tutorials; the main page can be found here. The tutorial uses tdl version 1.6.0 and Python 3.5 |
Spells and Ranged Combat
#!/usr/bin/env python3
import tdl
from random import randint
import colors
import math
import textwrap
#actual size of the window
SCREEN_WIDTH = 80
SCREEN_HEIGHT = 50
#size of the map
MAP_WIDTH = 80
MAP_HEIGHT = 43
#sizes and coordinates relevant for the GUI
BAR_WIDTH = 20
PANEL_HEIGHT = 7
PANEL_Y = SCREEN_HEIGHT - PANEL_HEIGHT
MSG_X = BAR_WIDTH + 2
MSG_WIDTH = SCREEN_WIDTH - BAR_WIDTH - 2
MSG_HEIGHT = PANEL_HEIGHT - 1
INVENTORY_WIDTH = 50
#parameters for dungeon generator
ROOM_MAX_SIZE = 10
ROOM_MIN_SIZE = 6
MAX_ROOMS = 30
MAX_ROOM_MONSTERS = 3
MAX_ROOM_ITEMS = 2
#spell values
HEAL_AMOUNT = 4
LIGHTNING_DAMAGE = 20
LIGHTNING_RANGE = 5
CONFUSE_RANGE = 8
CONFUSE_NUM_TURNS = 10
FIREBALL_RADIUS = 3
FIREBALL_DAMAGE = 12
FOV_ALGO = 'BASIC'
FOV_LIGHT_WALLS = True
TORCH_RADIUS = 10
LIMIT_FPS = 20 #20 frames-per-second maximum
color_dark_wall = (0, 0, 100)
color_light_wall = (130, 110, 50)
color_dark_ground = (50, 50, 150)
color_light_ground = (200, 180, 50)
class Tile:
#a tile of the map and its properties
def __init__(self, blocked, block_sight=None):
self.blocked = blocked
#all tiles start unexplored
self.explored = False
#by default, if a tile is blocked, it also blocks sight
if block_sight is None:
block_sight = blocked
self.block_sight = block_sight
class Rect:
#a rectangle on the map. used to characterize a room.
def __init__(self, x, y, w, h):
self.x1 = x
self.y1 = y
self.x2 = x + w
self.y2 = y + h
def center(self):
center_x = (self.x1 + self.x2) // 2
center_y = (self.y1 + self.y2) // 2
return (center_x, center_y)
def intersect(self, other):
#returns true if this rectangle intersects with another one
return (self.x1 <= other.x2 and self.x2 >= other.x1 and
self.y1 <= other.y2 and self.y2 >= other.y1)
class GameObject:
#this is a generic object: the player, a monster, an item, the stairs...
#it's always represented by a character on screen.
def __init__(self, x, y, char, name, color, blocks=False,
fighter=None, ai=None, item=None):
self.x = x
self.y = y
self.char = char
self.color = color
self.name = name
self.blocks = blocks
self.fighter = fighter
if self.fighter: #let the fighter component know who owns it
self.fighter.owner = self
self.ai = ai
if self.ai: #let the AI component know who owns it
self.ai.owner = self
self.item = item
if self.item: #let the Item component know who owns it
self.item.owner = self
def move(self, dx, dy):
#move by the given amount, if the destination is not blocked
if not is_blocked(self.x + dx, self.y + dy):
self.x += dx
self.y += dy
def move_towards(self, target_x, target_y):
#vector from this object to the target, and distance
dx = target_x - self.x
dy = target_y - self.y
distance = math.sqrt(dx ** 2 + dy ** 2)
#normalize it to length 1 (preserving direction), then round it and
#convert to integer so the movement is restricted to the map grid
dx = int(round(dx / distance))
dy = int(round(dy / distance))
self.move(dx, dy)
def distance_to(self, other):
#return the distance to another object
dx = other.x - self.x
dy = other.y - self.y
return math.sqrt(dx ** 2 + dy ** 2)
def distance(self, x, y):
#return the distance to some coordinates
return math.sqrt((x - self.x) ** 2 + (y - self.y) ** 2)
def send_to_back(self):
#make this object be drawn first, so all others appear above it if
#they're in the same tile.
global objects
objects.remove(self)
objects.insert(0, self)
def draw(self):
global visible_tiles
#only show if it's visible to the player
if (self.x, self.y) in visible_tiles:
#draw the character that represents this object at its position
con.draw_char(self.x, self.y, self.char, self.color, bg=None)
def clear(self):
#erase the character that represents this object
con.draw_char(self.x, self.y, ' ', self.color, bg=None)
class Fighter:
#combat-related properties and methods (monster, player, NPC).
def __init__(self, hp, defense, power, death_function=None):
self.max_hp = hp
self.hp = hp
self.defense = defense
self.power = power
self.death_function = death_function
def take_damage(self, damage):
#apply damage if possible
if damage > 0:
self.hp -= damage
#check for death. if there's a death function, call it
if self.hp <= 0:
function = self.death_function
if function is not None:
function(self.owner)
def attack(self, target):
#a simple formula for attack damage
damage = self.power - target.fighter.defense
if damage > 0:
#make the target take some damage
message(self.owner.name.capitalize() + ' attacks ' + target.name +
' for ' + str(damage) + ' hit points.')
target.fighter.take_damage(damage)
else:
message(self.owner.name.capitalize() + ' attacks ' + target.name +
' but it has no effect!')
def heal(self, amount):
#heal by the given amount, without going over the maximum
self.hp += amount
if self.hp > self.max_hp:
self.hp = self.max_hp
class BasicMonster:
#AI for a basic monster.
def take_turn(self):
#a basic monster takes its turn. If you can see it, it can see you
monster = self.owner
if (monster.x, monster.y) in visible_tiles:
#move towards player if far away
if monster.distance_to(player) >= 2:
monster.move_towards(player.x, player.y)
#close enough, attack! (if the player is still alive.)
elif player.fighter.hp > 0:
monster.fighter.attack(player)
class ConfusedMonster:
#AI for a temporarily confused monster (reverts to previous AI after a while).
def __init__(self, old_ai, num_turns=CONFUSE_NUM_TURNS):
self.old_ai = old_ai
self.num_turns = num_turns
def take_turn(self):
if self.num_turns > 0: #still confused...
#move in a random direction, and decrease the number of turns confused
self.owner.move(randint(-1, 1), randint(-1, 1))
self.num_turns -= 1
else:
#restore the previous AI (this one will be deleted because it's not
#referenced anymore)
self.owner.ai = self.old_ai
message('The ' + self.owner.name + ' is no longer confused!', colors.red)
class Item:
#an item that can be picked up and used.
def __init__(self, use_function=None):
self.use_function = use_function
def pick_up(self):
#add to the player's inventory and remove from the map
if len(inventory) >= 26:
message('Your inventory is full, cannot pick up ' +
self.owner.name + '.', colors.red)
else:
inventory.append(self.owner)
objects.remove(self.owner)
message('You picked up a ' + self.owner.name + '!', colors.green)
def drop(self):
#add to the map and remove from the player's inventory. also, place it at the player's coordinates
objects.append(self.owner)
inventory.remove(self.owner)
self.owner.x = player.x
self.owner.y = player.y
message('You dropped a ' + self.owner.name + '.', colors.yellow)
def use(self):
#just call the "use_function" if it is defined
if self.use_function is None:
message('The ' + self.owner.name + ' cannot be used.')
else:
if self.use_function() != 'cancelled':
inventory.remove(self.owner) #destroy after use, unless it was
#cancelled for some reason
def is_blocked(x, y):
#first test the map tile
if my_map[x][y].blocked:
return True
#now check for any blocking objects
for object in objects:
if object.blocks and object.x == x and object.y == y:
return True
return False
def create_room(room):
global my_map
#go through the tiles in the rectangle and make them passable
for x in range(room.x1 + 1, room.x2):
for y in range(room.y1 + 1, room.y2):
my_map[x][y].blocked = False
my_map[x][y].block_sight = False
def create_h_tunnel(x1, x2, y):
global my_map
for x in range(min(x1, x2), max(x1, x2) + 1):
my_map[x][y].blocked = False
my_map[x][y].block_sight = False
def create_v_tunnel(y1, y2, x):
global my_map
#vertical tunnel
for y in range(min(y1, y2), max(y1, y2) + 1):
my_map[x][y].blocked = False
my_map[x][y].block_sight = False
def is_visible_tile(x, y):
global my_map
if x >= MAP_WIDTH or x < 0:
return False
elif y >= MAP_HEIGHT or y < 0:
return False
elif my_map[x][y].blocked == True:
return False
elif my_map[x][y].block_sight == True:
return False
else:
return True
def make_map():
global my_map
#fill map with "blocked" tiles
my_map = [[ Tile(True)
for y in range(MAP_HEIGHT) ]
for x in range(MAP_WIDTH) ]
rooms = []
num_rooms = 0
for r in range(MAX_ROOMS):
#random width and height
w = randint(ROOM_MIN_SIZE, ROOM_MAX_SIZE)
h = randint(ROOM_MIN_SIZE, ROOM_MAX_SIZE)
#random position without going out of the boundaries of the map
x = randint(0, MAP_WIDTH-w-1)
y = randint(0, MAP_HEIGHT-h-1)
#"Rect" class makes rectangles easier to work with
new_room = Rect(x, y, w, h)
#run through the other rooms and see if they intersect with this one
failed = False
for other_room in rooms:
if new_room.intersect(other_room):
failed = True
break
if not failed:
#this means there are no intersections, so this room is valid
#"paint" it to the map's tiles
create_room(new_room)
#center coordinates of new room, will be useful later
(new_x, new_y) = new_room.center()
if num_rooms == 0:
#this is the first room, where the player starts at
player.x = new_x
player.y = new_y
else:
#all rooms after the first:
#connect it to the previous room with a tunnel
#center coordinates of previous room
(prev_x, prev_y) = rooms[num_rooms-1].center()
#draw a coin (random number that is either 0 or 1)
if randint(0, 1):
#first move horizontally, then vertically
create_h_tunnel(prev_x, new_x, prev_y)
create_v_tunnel(prev_y, new_y, new_x)
else:
#first move vertically, then horizontally
create_v_tunnel(prev_y, new_y, prev_x)
create_h_tunnel(prev_x, new_x, new_y)
#add some contents to this room, such as monsters
place_objects(new_room)
#finally, append the new room to the list
rooms.append(new_room)
num_rooms += 1
def place_objects(room):
#choose random number of monsters
num_monsters = randint(0, MAX_ROOM_MONSTERS)
for i in range(num_monsters):
#choose random spot for this monster
x = randint(room.x1+1, room.x2-1)
y = randint(room.y1+1, room.y2-1)
#only place it if the tile is not blocked
if not is_blocked(x, y):
if randint(0, 100) < 80: #80% chance of getting an orc
#create an orc
fighter_component = Fighter(hp=10, defense=0, power=3,
death_function=monster_death)
ai_component = BasicMonster()
monster = GameObject(x, y, 'o', 'orc', colors.desaturated_green,
blocks=True, fighter=fighter_component, ai=ai_component)
else:
#create a troll
fighter_component = Fighter(hp=16, defense=1, power=4,
death_function=monster_death)
ai_component = BasicMonster()
monster = GameObject(x, y, 'T', 'troll', colors.darker_green,
blocks=True, fighter=fighter_component, ai=ai_component)
objects.append(monster)
#choose random number of items
num_items = randint(0, MAX_ROOM_ITEMS)
for i in range(num_items):
#choose random spot for this item
x = randint(room.x1+1, room.x2-1)
y = randint(room.y1+1, room.y2-1)
#only place it if the tile is not blocked
if not is_blocked(x, y):
dice = randint(0, 100)
if dice < 70:
#create a healing potion (70% chance)
item_component = Item(use_function=cast_heal)
item = GameObject(x, y, '!', 'healing potion',
colors.violet, item=item_component)
elif dice < 70+10:
#create a lightning bolt scroll (15% chance)
item_component = Item(use_function=cast_lightning)
item = GameObject(x, y, '#', 'scroll of lightning bolt',
colors.light_yellow, item=item_component)
elif dice < 70+10+10:
#create a fireball scroll (10% chance)
item_component = Item(use_function=cast_fireball)
item = GameObject(x, y, '#', 'scroll of fireball',
colors.light_yellow, item=item_component)
else:
#create a confuse scroll (15% chance)
item_component = Item(use_function=cast_confuse)
item = GameObject(x, y, '#', 'scroll of confusion',
colors.light_yellow, item=item_component)
objects.append(item)
item.send_to_back() #items appear below other objects
def render_bar(x, y, total_width, name, value, maximum, bar_color, back_color):
#render a bar (HP, experience, etc). first calculate the width of the bar
bar_width = int(float(value) / maximum * total_width)
#render the background first
panel.draw_rect(x, y, total_width, 1, None, bg=back_color)
#now render the bar on top
if bar_width > 0:
panel.draw_rect(x, y, bar_width, 1, None, bg=bar_color)
#finally, some centered text with the values
text = name + ': ' + str(value) + '/' + str(maximum)
x_centered = x + (total_width-len(text))//2
panel.draw_str(x_centered, y, text, fg=colors.white, bg=None)
def get_names_under_mouse():
#return a string with the names of all objects under the mouse
(x, y) = mouse_coord
#create a list with the names of all objects at the mouse's coordinates and in FOV
names = [obj.name for obj in objects
if obj.x == x and obj.y == y and (obj.x, obj.y) in visible_tiles]
names = ', '.join(names) #join the names, separated by commas
return names.capitalize()
def render_all():
global fov_recompute
global visible_tiles
if fov_recompute:
fov_recompute = False
visible_tiles = tdl.map.quickFOV(player.x, player.y,
is_visible_tile,
fov=FOV_ALGO,
radius=TORCH_RADIUS,
lightWalls=FOV_LIGHT_WALLS)
#go through all tiles, and set their background color according to the FOV
for y in range(MAP_HEIGHT):
for x in range(MAP_WIDTH):
visible = (x, y) in visible_tiles
wall = my_map[x][y].block_sight
if not visible:
#if it's not visible right now, the player can only see it
#if it's explored
if my_map[x][y].explored:
if wall:
con.draw_char(x, y, None, fg=None, bg=color_dark_wall)
else:
con.draw_char(x, y, None, fg=None, bg=color_dark_ground)
else:
if wall:
con.draw_char(x, y, None, fg=None, bg=color_light_wall)
else:
con.draw_char(x, y, None, fg=None, bg=color_light_ground)
#since it's visible, explore it
my_map[x][y].explored = True
#draw all objects in the list
for obj in objects:
if obj != player:
obj.draw()
player.draw()
#blit the contents of "con" to the root console and present it
root.blit(con, 0, 0, MAP_WIDTH, MAP_HEIGHT, 0, 0)
#prepare to render the GUI panel
panel.clear(fg=colors.white, bg=colors.black)
#print the game messages, one line at a time
y = 1
for (line, color) in game_msgs:
panel.draw_str(MSG_X, y, line, bg=None, fg=color)
y += 1
#show the player's stats
render_bar(1, 1, BAR_WIDTH, 'HP', player.fighter.hp, player.fighter.max_hp,
colors.light_red, colors.darker_red)
#display names of objects under the mouse
panel.draw_str(1, 0, get_names_under_mouse(), bg=None, fg=colors.light_gray)
#blit the contents of "panel" to the root console
root.blit(panel, 0, PANEL_Y, SCREEN_WIDTH, PANEL_HEIGHT, 0, 0)
def message(new_msg, color = colors.white):
#split the message if necessary, among multiple lines
new_msg_lines = textwrap.wrap(new_msg, MSG_WIDTH)
for line in new_msg_lines:
#if the buffer is full, remove the first line to make room for the new one
if len(game_msgs) == MSG_HEIGHT:
del game_msgs[0]
#add the new line as a tuple, with the text and the color
game_msgs.append((line, color))
def player_move_or_attack(dx, dy):
global fov_recompute
#the coordinates the player is moving to/attacking
x = player.x + dx
y = player.y + dy
#try to find an attackable object there
target = None
for object in objects:
if object.fighter and object.x == x and object.y == y:
target = object
break
#attack if target found, move otherwise
if target is not None:
player.fighter.attack(target)
else:
player.move(dx, dy)
fov_recompute = True
def menu(header, options, width):
if len(options) > 26:
raise ValueError ('Cannot have a menu with more than 26 options.')
#calculate total height for the header (after textwrap) and one line per option
header_wrapped = textwrap.wrap(header, width)
header_height = len(header_wrapped)
height = len(options) + header_height
#create an off-screen console that represents the menu's window
window = tdl.Console(width, height)
#print the header, with wrapped text
window.draw_rect(0, 0, width, height, None, fg=colors.white, bg=None)
for i, line in enumerate(header_wrapped):
window.draw_str(0, 0+i, header_wrapped[i])
#print all the options
y = header_height
letter_index = ord('a')
for option_text in options:
text = '(' + chr(letter_index) + ') ' + option_text
window.draw_str(0, y, text, bg=None)
y += 1
letter_index += 1
#blit the contents of "window" to the root console
x = SCREEN_WIDTH//2 - width//2
y = SCREEN_HEIGHT//2 - height//2
root.blit(window, x, y, width, height, 0, 0, fg_alpha=1.0, bg_alpha=0.7)
#present the root console to the player and wait for a key-press
tdl.flush()
key = tdl.event.key_wait()
key_char = key.char
if key_char == '':
key_char = ' ' # placeholder
#convert the ASCII code to an index; if it corresponds to an option, return it
index = ord(key_char) - ord('a')
if index >= 0 and index < len(options):
return index
return None
def inventory_menu(header):
#show a menu with each item of the inventory as an option
if len(inventory) == 0:
options = ['Inventory is empty.']
else:
options = [item.name for item in inventory]
index = menu(header, options, INVENTORY_WIDTH)
#if an item was chosen, return it
if index is None or len(inventory) == 0:
return None
return inventory[index].item
def handle_keys():
global playerx, playery
global fov_recompute
global mouse_coord
keypress = False
for event in tdl.event.get():
if event.type == 'KEYDOWN':
user_input = event
keypress = True
if event.type == 'MOUSEMOTION':
mouse_coord = event.cell
if not keypress:
return 'didnt-take-turn' #TODO: Add to tutorial
if user_input.key == 'ENTER' and user_input.alt:
#Alt+Enter: toggle fullscreen
tdl.set_fullscreen(True)
elif user_input.key == 'ESCAPE':
return 'exit' #exit game
if game_state == 'playing':
#movement keys
if user_input.key == 'UP':
player_move_or_attack(0, -1)
elif user_input.key == 'DOWN':
player_move_or_attack(0, 1)
elif user_input.key == 'LEFT':
player_move_or_attack(-1, 0)
elif user_input.key == 'RIGHT':
player_move_or_attack(1, 0)
else:
#test for other keys
if user_input.char == 'g':
#pick up an item
for obj in objects: #look for an item in the player's tile
if obj.x == player.x and obj.y == player.y and obj.item:
obj.item.pick_up()
break
if user_input.char == 'i':
#show the inventory; if an item is selected, use it
chosen_item = inventory_menu('Press the key next to an item to ' +
'use it, or any other to cancel.\n')
if chosen_item is not None:
chosen_item.use()
if user_input.char == 'd':
#show the inventory; if an item is selected, drop it
chosen_item = inventory_menu('Press the key next to an item to' +
'drop it, or any other to cancel.\n')
if chosen_item is not None:
chosen_item.drop()
return 'didnt-take-turn'
def player_death(player):
#the game ended!
global game_state
message('You died!', colors.red)
game_state = 'dead'
#for added effect, transform the player into a corpse!
player.char = '%'
player.color = colors.dark_red
def monster_death(monster):
#transform it into a nasty corpse! it doesn't block, can't be
#attacked and doesn't move
message(monster.name.capitalize() + ' is dead!', colors.orange)
monster.char = '%'
monster.color = colors.dark_red
monster.blocks = False
monster.fighter = None
monster.ai = None
monster.name = 'remains of ' + monster.name
monster.send_to_back()
def target_tile(max_range=None):
#return the position of a tile left-clicked in player's FOV (optionally in
#a range), or (None,None) if right-clicked.
global mouse_coord
while True:
#render the screen. this erases the inventory and shows the names of
#objects under the mouse.
tdl.flush()
clicked = False
for event in tdl.event.get():
if event.type == 'MOUSEMOTION':
mouse_coord = event.cell
if event.type == 'MOUSEDOWN' and event.button == 'LEFT':
clicked = True
elif ((event.type == 'MOUSEDOWN' and event.button == 'RIGHT') or
(event.type == 'KEYDOWN' and event.key == 'ESCAPE')):
return (None, None)
render_all()
#accept the target if the player clicked in FOV, and in case a range is
#specified, if it's in that range
x = mouse_coord[0]
y = mouse_coord[1]
if (clicked and mouse_coord in visible_tiles and
(max_range is None or player.distance(x, y) <= max_range)):
return mouse_coord
def target_monster(max_range=None):
#returns a clicked monster inside FOV up to a range, or None if right-clicked
while True:
(x, y) = target_tile(max_range)
if x is None: #player cancelled
return None
#return the first clicked monster, otherwise continue looping
for obj in objects:
if obj.x == x and obj.y == y and obj.fighter and obj != player:
return obj
def closest_monster(max_range):
#find closest enemy, up to a maximum range, and in the player's FOV
closest_enemy = None
closest_dist = max_range + 1 #start with (slightly more than) maximum range
for obj in objects:
if obj.fighter and not obj == player and (obj.x, obj.y) in visible_tiles:
#calculate distance between this object and the player
dist = player.distance_to(obj)
if dist < closest_dist: #it's closer, so remember it
closest_enemy = obj
closest_dist = dist
return closest_enemy
def cast_heal():
#heal the player
if player.fighter.hp == player.fighter.max_hp:
message('You are already at full health.', colors.red)
return 'cancelled'
message('Your wounds start to feel better!', colors.light_violet)
player.fighter.heal(HEAL_AMOUNT)
def cast_lightning():
#find closest enemy (inside a maximum range) and damage it
monster = closest_monster(LIGHTNING_RANGE)
if monster is None: #no enemy found within maximum range
message('No enemy is close enough to strike.', colors.red)
return 'cancelled'
#zap it!
message('A lighting bolt strikes the ' + monster.name + ' with a loud ' +
'thunder! The damage is ' + str(LIGHTNING_DAMAGE) + ' hit points.',
colors.light_blue)
monster.fighter.take_damage(LIGHTNING_DAMAGE)
def cast_confuse():
#ask the player for a target to confuse
message('Left-click an enemy to confuse it, or right-click to cancel.',
colors.light_cyan)
monster = target_monster(CONFUSE_RANGE)
if monster is None:
message('Cancelled')
return 'cancelled'
#replace the monster's AI with a "confused" one; after some turns it will
#restore the old AI
old_ai = monster.ai
monster.ai = ConfusedMonster(old_ai)
monster.ai.owner = monster #tell the new component who owns it
message('The eyes of the ' + monster.name + ' look vacant, as he starts to ' +
'stumble around!', colors.light_green)
def cast_fireball():
#ask the player for a target tile to throw a fireball at
message('Left-click a target tile for the fireball, or right-click to ' +
'cancel.', colors.light_cyan)
(x, y) = target_tile()
if x is None:
message('Cancelled')
return 'cancelled'
message('The fireball explodes, burning everything within ' +
str(FIREBALL_RADIUS) + ' tiles!', colors.orange)
for obj in objects: #damage every fighter in range, including the player
if obj.distance(x, y) <= FIREBALL_RADIUS and obj.fighter:
message('The ' + obj.name + ' gets burned for ' +
str(FIREBALL_DAMAGE) + ' hit points.', colors.orange)
obj.fighter.take_damage(FIREBALL_DAMAGE)
#############################################
# Initialization & Main Loop #
#############################################
tdl.set_font('arial10x10.png', greyscale=True, altLayout=True)
root = tdl.init(SCREEN_WIDTH, SCREEN_HEIGHT, title="Roguelike",
fullscreen=False)
tdl.setFPS(LIMIT_FPS)
con = tdl.Console(MAP_WIDTH, MAP_HEIGHT)
panel = tdl.Console(SCREEN_WIDTH, PANEL_HEIGHT)
#create object representing the player
fighter_component = Fighter(hp=30, defense=2, power=5,
death_function=player_death)
player = GameObject(0, 0, '@', 'player', colors.white, blocks=True,
fighter=fighter_component)
#the list of objects with those two
objects = [player]
#generate map (at this point it's not drawn to the screen)
make_map()
fov_recompute = True
game_state = 'playing'
player_action = None
inventory = []
#create the list of game messages and their colors, starts empty
game_msgs = []
#a warm welcoming message!
message('Welcome stranger! Prepare to perish in the Tombs of the Ancient Kings.',
colors.red)
mouse_coord = (0, 0)
while not tdl.event.is_window_closed():
#draw all objects in the list
render_all()
tdl.flush()
#erase all objects at their old locations, before they move
for obj in objects:
obj.clear()
#handle keys and exit game if needed
player_action = handle_keys()
if player_action == 'exit':
break
#let monsters take their turn
if game_state == 'playing' and player_action != 'didnt-take-turn':
for obj in objects:
if obj.ai:
obj.ai.take_turn()