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=begin
Reminders:
- args.state.new_entity: Used when we want to create a new object, like a sprite or button.
For example, if we want to create a new button, we would 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.)
- args.outputs.solids: An array. The values generate a solid.
The parameters for a solid are [X, Y, WIDTH, HEIGHT, RED, GREEN, BLUE]
- num1.greater(num2): Returns the greater value.
- Hashes: Collection of unique keys and their corresponding values. The value can be found
using their keys.
- ARRAY#inside_rect?: Returns true or false depending on if the point is inside the rect.
=end
# This sample app is a game that requires the user to jump from one platform to the next.
# As the player successfully clears platforms, they become smaller and move faster.
class VerticalPlatformer
attr_gtk
# declares vertical platformer as new entity
def s
state.vertical_platformer ||= state.new_entity(:vertical_platformer)
state.vertical_platformer
end
# creates a new platform using a hash
def new_platform hash
s.new_entity_strict(:platform, hash) # platform key
end
# calls methods needed for game to run properly
def tick
defaults
render
calc
input
end
# Sets default values
def defaults
s.platforms ||= [ # initializes platforms collection with two platforms using hashes
new_platform(x: 0, y: 0, w: 700, h: 32, dx: 1, speed: 0, rect: nil),
new_platform(x: 0, y: 300, w: 700, h: 32, dx: 1, speed: 0, rect: nil), # 300 pixels higher
]
s.tick_count = args.state.tick_count
s.gravity = -0.3 # what goes up must come down because of gravity
s.player.platforms_cleared ||= 0 # counts how many platforms the player has successfully cleared
s.player.x ||= 0 # sets player values
s.player.y ||= 100
s.player.w ||= 64
s.player.h ||= 64
s.player.dy ||= 0 # change in position
s.player.dx ||= 0
s.player_jump_power = 15
s.player_jump_power_duration = 10
s.player_max_run_speed = 5
s.player_speed_slowdown_rate = 0.9
s.player_acceleration = 1
s.camera ||= { y: -100 } # shows view on screen (as the player moves upward, the camera does too)
end
# Outputs objects onto the screen
def render
outputs.solids << s.platforms.map do |p| # outputs platforms onto screen
[p.x + 300, p.y - s.camera[:y], p.w, p.h] # add 300 to place platform in horizontal center
# don't forget, position of platform is denoted by bottom left hand corner
end
# outputs player using hash
outputs.solids << {
x: s.player.x + 300, # player positioned on top of platform
y: s.player.y - s.camera[:y],
w: s.player.w,
h: s.player.h,
r: 100, # color saturation
g: 100,
b: 200
}
end
# Performs calculations
def calc
s.platforms.each do |p| # for each platform in the collection
p.rect = [p.x, p.y, p.w, p.h] # set the definition
end
# sets player point by adding half the player's width to the player's x
s.player.point = [s.player.x + s.player.w.half, s.player.y] # change + to - and see what happens!
# search the platforms collection to find if the player's point is inside the rect of a platform
collision = s.platforms.find { |p| s.player.point.inside_rect? p.rect }
# if collision occurred and player is moving down (or not moving vertically at all)
if collision && s.player.dy <= 0
s.player.y = collision.rect.y + collision.rect.h - 2 # player positioned on top of platform
s.player.dy = 0 if s.player.dy < 0 # player stops moving vertically
if !s.player.platform
s.player.dx = 0 # no horizontal movement
end
# changes horizontal position of player by multiplying collision change in x (dx) by speed and adding it to current x
s.player.x += collision.dx * collision.speed
s.player.platform = collision # player is on the platform that it collided with (or landed on)
if s.player.falling # if player is falling
s.player.dx = 0 # no horizontal movement
end
s.player.falling = false
s.player.jumped_at = nil
else
s.player.platform = nil # player is not on a platform
s.player.y += s.player.dy # velocity is the change in position
s.player.dy += s.gravity # acceleration is the change in velocity; what goes up must come down
end
s.platforms.each do |p| # for each platform in the collection
p.x += p.dx * p.speed # x is incremented by product of dx and speed (causes platform to move horizontally)
# changes platform's x so it moves left and right across the screen (between -300 and 300 pixels)
if p.x < -300 # if platform goes too far left
p.dx *= -1 # dx is scaled down
p.x = -300 # as far left as possible within scope
elsif p.x > (1000 - p.w) # if platform's x is greater than 300
p.dx *= -1
p.x = (1000 - p.w) # set to 300 (as far right as possible within scope)
end
end
delta = (s.player.y - s.camera[:y] - 100) # used to position camera view
if delta > -200
s.camera[:y] += delta * 0.01 # allows player to see view as they move upwards
s.player.x += s.player.dx # velocity is change in position; change in x increases by dx
# searches platform collection to find platforms located more than 300 pixels above the player
has_platforms = s.platforms.find { |p| p.y > (s.player.y + 300) }
if !has_platforms # if there are no platforms 300 pixels above the player
width = 700 - (700 * (0.1 * s.player.platforms_cleared)) # the next platform is smaller than previous
s.player.platforms_cleared += 1 # player successfully cleared another platform
last_platform = s.platforms[-1] # platform just cleared becomes last platform
# another platform is created 300 pixels above the last platform, and this
# new platform has a smaller width and moves faster than all previous platforms
s.platforms << new_platform(x: (700 - width) * rand, # random x position
y: last_platform.y + 300,
w: width,
h: 32,
dx: 1.randomize(:sign), # random change in x
speed: 2 * s.player.platforms_cleared,
rect: nil)
end
else
s.as_hash.clear # otherwise clear the hash (no new platform is necessary)
end
end
# Takes input from the user to move the player
def input
if inputs.keyboard.space # if the space bar is pressed
s.player.jumped_at ||= s.tick_count # set to current frame
# if the time that has passed since the jump is less than the duration of a jump (10 frames)
# and the player is not falling
if s.player.jumped_at.elapsed_time < s.player_jump_power_duration && !s.player.falling
s.player.dy = s.player_jump_power # player jumps up
end
end
if inputs.keyboard.key_up.space # if space bar is in "up" state
s.player.falling = true # player is falling
end
if inputs.keyboard.left # if left key is pressed
s.player.dx -= s.player_acceleration # player's position changes, decremented by acceleration
s.player.dx = s.player.dx.greater(-s.player_max_run_speed) # dx is either current dx or -5, whichever is greater
elsif inputs.keyboard.right # if right key is pressed
s.player.dx += s.player_acceleration # player's position changes, incremented by acceleration
s.player.dx = s.player.dx.lesser(s.player_max_run_speed) # dx is either current dx or 5, whichever is lesser
else
s.player.dx *= s.player_speed_slowdown_rate # scales dx down
end
end
end
$game = VerticalPlatformer.new
def tick args
$game.args = args
$game.tick
end
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