=begin
Reminders:
- find_all: Finds all elements of a collection that meet certain requirements.
For example, in this sample app, we're using find_all to find all zombies that have intersected
or hit the player's sprite since these zombies have been killed.
- args.inputs.keyboard.key_down.KEY: Determines if a key is being held or pressed.
Stores the frame the "down" event occurred.
For more information about the keyboard, go to mygame/documentation/06-keyboard.md.
- args.outputs.sprites: An array. The values generate a sprite.
The parameters are [X, Y, WIDTH, HEIGHT, PATH, ANGLE, ALPHA, RED, GREEN, BLUE]
For more information about sprites, go to mygame/documentation/05-sprites.md.
- args.state.new_entity: Used when we want to create a new object, like a sprite or button.
When we want to create a new object, we can declare it as a new entity and then define
its properties. (Remember, you can use state to define ANY property and it will
be retained across frames.)
- String interpolation: Uses #{} syntax; everything between the #{ and the } is evaluated
as Ruby code, and the placeholder is replaced with its corresponding value or result.
- map: Ruby method used to transform data; used in arrays, hashes, and collections.
Can be used to perform an action on every element of a collection, such as multiplying
each element by 2 or declaring every element as a new entity.
- sample: Chooses a random element from the array.
- reject: Removes elements that meet certain requirements.
In this sample app, we're removing/rejecting zombies that reach the center of the screen. We're also
rejecting zombies that were killed more than 30 frames ago.
=end
# This sample app allows users to move around the screen in order to kill zombies. Zombies appear from every direction so the goal
# is to kill the zombies as fast as possible!
class ProtectThePuppiesFromTheZombies
attr_accessor :grid, :inputs, :state, :outputs
# Calls the methods necessary for the game to run properly.
def tick
defaults
render
calc
input
end
# Sets default values for the zombies and for the player.
# Initialization happens only in the first frame.
def defaults
state.flash_at ||= 0
state.zombie_min_spawn_rate ||= 60
state.zombie_spawn_countdown ||= random_spawn_countdown state.zombie_min_spawn_rate
state.zombies ||= []
state.killed_zombies ||= []
# Declares player as a new entity and sets its properties.
# The player begins the game in the center of the screen, not moving in any direction.
state.player ||= { x: 640,
y: 360,
w: 4 * 3,
h: 8 * 3,
attack_angle: 0,
dx: 0,
dy: 0,
created_at: state.tick_count }
end
# Outputs a gray background.
# Calls the methods needed to output the player, zombies, etc onto the screen.
def render
outputs.background_color = [100, 100, 100]
render_zombies
render_killed_zombies
render_player
render_flash
end
# Outputs the zombies on the screen and sets values for the sprites, such as the position, width, height, and animation.
def render_zombies
outputs.sprites << state.zombies.map do |z| # performs action on all zombies in the collection
z.merge path: animation_sprite(z) # sets definition for sprite, calls animation_sprite method
end
end
# Outputs sprites of killed zombies, and displays a slash image to show that a zombie has been killed.
def render_killed_zombies
outputs.sprites << state.killed_zombies.map do |z| # performs action on all killed zombies in collection
zombie = { x: z.x,
y: z.y,
w: 4 * 3,
h: 8 * 3,
path: animation_sprite(z, z.death_at), # calls animation_sprite method
a: 255 * z.death_at.ease(30, :flip) } # transparency of a zombie changes when they die
# Sets values to output the slash over the zombie's sprite when a zombie is killed.
# The slash is tilted 45 degrees from the angle of the player's attack.
# Change the 3 inside scale_rect to 30 and the slash will be HUGE! Scale_rect positions
# the slash over the killed zombie's sprite.
[zombie,
zombie.merge(path: 'sprites/slash.png',
angle: 45 + (state.player.attack_angle_on_click || 0)).scale_rect(3, 0.5, 0.5)]
end
end
# Outputs the player sprite using the images in the sprites folder.
def render_player
# Outputs a small red square that previews the angles that the player can attack in.
# It can be moved in a perfect circle around the player to show possible movements.
# Change the 60 in the parenthesis and see what happens to the movement of the red square.
outputs.sprites << { x: state.player.x + state.player.attack_angle.vector_x(60),
y: state.player.y + state.player.attack_angle.vector_y(60),
w: 3,
h: 3,
r: 255,
g: 0,
b: 0,
path: :solid }
outputs.sprites << { x: state.player.x,
y: state.player.y,
w: 4 * 3,
h: 8 * 3,
path: "sprites/player-#{animation_index(state.player.created_at.elapsed_time)}.png" } # string interpolation
end
# Renders flash as a solid. The screen turns white for 10 frames when a zombie is killed.
def render_flash
return if state.flash_at.elapsed_time > 10 # return if more than 10 frames have passed since flash.
# Transparency gradually changes (or eases) during the 10 frames of flash.
outputs.primitives << { **grid.rect, r: 255, g: 255, b: 255, a: 255 * state.flash_at.ease(10, :flip), path: :solid }
end
# Calls all methods necessary for performing calculations.
def calc
calc_spawn_zombie
calc_move_zombies
calc_player
calc_kill_zombie
end
# Decreases the zombie spawn countdown by 1 if it has a value greater than 0.
def calc_spawn_zombie
if state.zombie_spawn_countdown > 0
state.zombie_spawn_countdown -= 1
return
end
# New zombies are created, positioned on the screen, and added to the zombies collection.
state.zombies << (if rand > 0.5
{
x: grid.rect.w.randomize(:ratio), # random x position on screen (within grid scope)
y: [-10, 730].sample, # y position is set to either -10 or 730 (randomly chosen)
w: 4 * 3, h: 8 * 3,
created_at: state.tick_count
}
else
{
x: [-10, 1290].sample, # x position is set to either -10 or 1290 (randomly chosen)
y: grid.rect.w.randomize(:ratio), # random y position on screen
w: 4 * 3, h: 8 * 3,
created_at: state.tick_count
}
end)
# Calls random_spawn_countdown method (determines how fast new zombies appear)
state.zombie_spawn_countdown = random_spawn_countdown state.zombie_min_spawn_rate
state.zombie_min_spawn_rate -= 1
# set to either the current zombie_min_spawn_rate or 0, depending on which value is greater
state.zombie_min_spawn_rate = state.zombie_min_spawn_rate.clamp(0)
end
# Moves all zombies towards the center of the screen.
# All zombies that reach the center (640, 360) are rejected from the zombies collection and disappear.
def calc_move_zombies
state.zombies.each do |z| # for each zombie in the collection
z.y = z.y.towards(360, 0.1) # move the zombie towards the center (640, 360) at a rate of 0.1
z.x = z.x.towards(640, 0.1) # change 0.1 to 1.1 and see how much faster the zombies move to the center
end
state.zombies = state.zombies.reject { |z| z.y == 360 && z.x == 640 } # remove zombies that are in center
end
# Calculates the position and movement of the player on the screen.
def calc_player
state.player.x += state.player.dx # changes x based on dx (change in x)
state.player.y += state.player.dy # changes y based on dy (change in y)
state.player.dx *= 0.9 # scales dx down
state.player.dy *= 0.9 # scales dy down
# Compares player's x to 1280 to find lesser value, then compares result to 0 to find greater value.
# This ensures that the player remains within the screen's scope.
state.player.x = state.player.x.clamp(0, 1280)
state.player.y = state.player.y.clamp(0, 720) # same with player's y
end
# Finds all zombies that intersect with the player's sprite. These zombies are removed from the zombies collection
# and added to the killed_zombies collection since any zombie that intersects with the player is killed.
def calc_kill_zombie
# Find all zombies that intersect with the player. They are considered killed.
killed_this_frame = state.zombies.find_all { |z| (z.intersect_rect? state.player) }
state.zombies = state.zombies - killed_this_frame # remove newly killed zombies from zombies collection
state.killed_zombies += killed_this_frame # add newly killed zombies to killed zombies
if killed_this_frame.length > 0 # if atleast one zombie was killed in the frame
state.flash_at = state.tick_count # flash_at set to the frame when the zombie was killed
# Don't forget, the rendered flash lasts for 10 frames after the zombie is killed (look at render_flash method)
end
# Sets the tick_count (passage of time) as the value of the death_at variable for each killed zombie.
# Death_at stores the frame a zombie was killed.
killed_this_frame.each do |z|
z.death_at = state.tick_count
end
# Zombies are rejected from the killed_zombies collection depending on when they were killed.
# They are rejected if more than 30 frames have passed since their death.
state.killed_zombies = state.killed_zombies.reject { |z| state.tick_count - z.death_at > 30 }
end
# Uses input from the user to move the player around the screen.
def input
# If the "a" key or left key is pressed, the x position of the player decreases.
# Otherwise, if the "d" key or right key is pressed, the x position of the player increases.
if inputs.keyboard.key_held.a || inputs.keyboard.key_held.left
state.player.x -= 5
elsif inputs.keyboard.key_held.d || inputs.keyboard.key_held.right
state.player.x += 5
end
# If the "w" or up key is pressed, the y position of the player increases.
# Otherwise, if the "s" or down key is pressed, the y position of the player decreases.
if inputs.keyboard.key_held.w || inputs.keyboard.key_held.up
state.player.y += 5
elsif inputs.keyboard.key_held.s || inputs.keyboard.key_held.down
state.player.y -= 5
end
# Sets the attack angle so the player can move and attack in the precise direction it wants to go.
# If the mouse is moved, the attack angle is changed (based on the player's position and mouse position).
# Attack angle also contributes to the position of red square.
if inputs.mouse.moved
state.player.attack_angle = inputs.mouse.position.angle_from [state.player.x, state.player.y]
end
if inputs.mouse.click && state.player.dx < 0.5 && state.player.dy < 0.5
state.player.attack_angle_on_click = inputs.mouse.position.angle_from [state.player.x, state.player.y]
state.player.attack_angle = state.player.attack_angle_on_click # player's attack angle is set
state.player.dx = state.player.attack_angle.vector_x(25) # change in player's position
state.player.dy = state.player.attack_angle.vector_y(25)
end
end
# Sets the zombie spawn's countdown to a random number.
# How fast zombies appear (change the 60 to 6 and too many zombies will appear at once!)
def random_spawn_countdown minimum
10.randomize(:ratio, :sign).to_i + 60
end
# Helps to iterate through the images in the sprites folder by setting the animation index.
# 3 frames is how long to show an image, and 6 is how many images to flip through.
def animation_index at
at.idiv(3).mod(6)
end
# Animates the zombies by using the animation index to go through the images in the sprites folder.
def animation_sprite zombie, at = nil
at ||= zombie.created_at.elapsed_time # how long it is has been since a zombie was created
index = animation_index at
"sprites/zombie-#{index}.png" # string interpolation to iterate through images
end
end
$protect_the_puppies_from_the_zombies = ProtectThePuppiesFromTheZombies.new
def tick args
$protect_the_puppies_from_the_zombies.grid = args.grid
$protect_the_puppies_from_the_zombies.inputs = args.inputs
$protect_the_puppies_from_the_zombies.state = args.state
$protect_the_puppies_from_the_zombies.outputs = args.outputs
$protect_the_puppies_from_the_zombies.tick
tick_instructions args, "How to get the mouse position and translate it to an x, y position using .vector_x and .vector_y. CLICK to play."
end
def tick_instructions args, text, y = 715
return if args.state.key_event_occurred
if args.inputs.mouse.click ||
args.inputs.keyboard.directional_vector ||
args.inputs.keyboard.key_down.enter ||
args.inputs.keyboard.key_down.escape
args.state.key_event_occurred = true
end
args.outputs.debug << [0, y - 50, 1280, 60].solid
args.outputs.debug << [640, y, text, 1, 1, 255, 255, 255].label
args.outputs.debug << [640, y - 25, "(click to dismiss instructions)" , -2, 1, 255, 255, 255].label
end