Question

Hello again Stack Overflow. you probably remember me from my unit spawning problem in my pygame program, “Table Wars.” I decided to change the scope of my game to a real-time strategy rather than a turn-based game. I want the game to play along the lines of top Flash game: “Age of War.” Almost everything works in the game: spawning units, the HUD for the game, and even base health. Unfortunately, I can’t seem to figure out how to implement the ability for units to attack enemies or the enemy base. Here is the concepts going on for the units themselves:

• The unit spawns on a keypress around the team’s base: K_1 spawns a sprite from the Red_Infantry class
• The unit, when spawned, is added to a Group class. There are two Groups, one for each team.
• The unit moves via a move_ip call within a def update until it reaches a point close to the enemy base, where it stops.

Here is how I want combat to go for the different units:

• The unit stops whenever it spots an enemy within it’s attack range. Different units have different attack ranges
• The unit then attacks in one-second intervals.
• If the unit sucessfully reduces the enemy unit’s health to 0, the enemy dies, and the other may continue
• This cycle repeats until the unit reaches the enemy base, where it will then attack the enemy base on one-second intervals. One of the units will be able to deal triple the normal damage to the base.

Here is a sample of my code, showing the Red_Infantry class:

class Red_Infantry(pygame.sprite.Sprite):
def __init__(self, screen):
    pygame.sprite.Sprite.__init__(self)
    self.image, self.rect = load_image('Soldier_red.png', -1)
    self.rect.move_ip(random.randint(75, 100), random.randint(275, 325))
    self.selected = 0
    self.area = screen.get_rect()
    self.health = 100 #Soldiers are have mediocre toughness.
    self.attack_damage = 25 #The amount of damage it deals
    self.range = 20 #The attack range of the unit.
    self.update()
def update(self):
    self.rect.move_ip(1, 0)
    if self.rect.right >= 725: #This position is close to the enemy base...
        self.rect.right = 725 #...where it will then stop
    if self.health <= 0:  
        self.kill() #a simple code that kills the sprite if his health reaches 0

The main loop only contains the ability to spawn each of the units.

Answer 1

Here’s a starting point

class RedInfantry(pygame.sprite.Sprite):
    def __init__(self):
        self.screen = pygame.display.get_surface()
        self.image, self.rect = load_image('Soldier_red.png', -1)    
        self.rect.move_ip(random.randint(75, 100), random.randint(275, 325))
        self.target = None
        self.range = 20
        self.attack_cooldown = 200
        self.attack_last = 0

    def move_toward(self, target):
        # move toward players click destination, if one is set.
        # else toward my attack target

    def update(self):
        # move...
        self.find_target()
        self.move_toward(self.target)
        self.attack()
        # check HP
        if self.health <= 0:
            self.kill()

    def find_target(self):
        """finds new targets in range:
        for speed: only call this once every 200ms."""
        if self.target is not None: return
        for enemy in B.sprites():
            if distance(self.rect.center, enemy.rect.center) <= self.range:
                self.target = enemy
                return
        # else no targets in range
        self.target = None  


    def attack(self):
        """attack, if able.
        target exists? still alive? gun cooldown good?"""
        if self.target is None: return
        if self.target.health <= 0: return
        if not self.cooldown_ready(): return

        # all good, fire. could verify still in range. 
        self.target.damage(self.attack_damage)

    def cooldown_ready(self):
        # gun ready to fire? has cooldown in MS elapsed.
        now = pygame.time.get_ticks()
        if now - self.attack_last >= self.attack_cooldown:
            self.attack_last = now
            return True
        return False