Class: Stalker

Inherits:
Enemy
  • Object
show all
Includes:
GamespacePersistence
Defined in:
lib/prkwars/stalker.rb

Overview

Class representing the Stalker enemy unit which is mobile but unable to shoot and endlessly moves towards the player unit.

Constant Summary collapse

VELOCITY = 
2
HP = 
1

Instance Attribute Summary

Attributes inherited from Enemy

#hp

Instance Method Summary collapse

Methods included from GamespacePersistence

#correct_coords, #in_bounds

Methods inherited from Enemy

descendants

Constructor Details

#initialize(gamespace, options = {}) ⇒ Stalker

Initialization of the Stalker unit requires the gamespace for collision checks, sets the sprite and HP of the unit to an instance variable.



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# File 'lib/prkwars/stalker.rb', line 18

def initialize(gamespace, options = {})
  super(options)

  @image = Image['./media/stalker.png']

  @gamespace = gamespace
  @hp = HP
end

Instance Method Details

#take_damage ⇒ Object

A common method to enemies, reducing their HP by one.



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# File 'lib/prkwars/stalker.rb', line 48

def take_damage
  @hp -= 1
end

#update ⇒ Object

Every time a Stalker unit gets updated, they move in a constant speed towards the player. Their sprite also gets rotated.



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# File 'lib/prkwars/stalker.rb', line 31

def update
  dist_x = @gamespace.player.x - @x
  dist_y = @gamespace.player.y - @y

  rot_to = Math.atan2(dist_y, dist_x) / Math::PI * 180 + 90

  dist = Math.sqrt(dist_x * dist_x + dist_y * dist_y)

  ticks = dist / VELOCITY

  @velocity_x = dist_x / ticks
  @velocity_y = dist_y / ticks
  @angle = rot_to
end