pgcooldown - Cooldown & co...

DESCRIPTION

This module started with just the Cooldown class, which can be used check if a specified time has passed. It is mostly indended to be used to control objects in a game loop, but it is general enough for other purposes as well.

fire_cooldown = Cooldown(1, cold=True)
while True:
    if fire_shot and fire_cooldown.cold():
        fire_cooldown.reset()
        launch_bullet()

    ...

With the usage of Cooldown on ramp data (e.g. a Lerp between an opaque and a fully transparent sprite over the time of n seconds), I came up with the LerpThing. The LerpThing gives you exactly that. A lerp between from and to mapped onto a duration.

alpha = LerpThing(0, 255, 5)
while True:
    ...
    sprite.set_alpha(alpha())
    # or sprite.set_alpha(alpha.v)

    if alpha.finished:
        sprite.kill()

Finally, the need to use Cooldown for scheduling the creations of game objects, the CronD class was added. It schedules functions to run after a wait period.

Note, that CronD doesn't do any magic background timer stuff, it needs to be updated in the game loop.

crond = CronD()
crond.add(1, create_enemy(screen.center))
crond.add(2, create_enemy(screen.center))
crond.add(3, create_enemy(screen.center))
crond.add(4, create_enemy(screen.center))

while True:
    ...
    crond.update()

CLASSES

Cooldown

c = Cooldown(c)

Track a cooldown over a period of time.

cooldown = Cooldown(5)

while True:
    do_stuff()

    if key_pressed
        if key == 'P':
            cooldown.pause()
        elif key == 'ESC':
            cooldown.start()

    if cooldown.cold():
        launch_stuff()
        cooldown.reset()

Cooldown can be used to time sprite animation frame changes, weapon cooldown in shmups, all sorts of events when programming a game.

If you want to use the cooldown more as a timing gauge, e.g. to modify acceleration of a sprite over time, have a look at the LerpThing class in this package, which makes this incredibly easy.

When instantiated (and started), Cooldown stores the current time. The cooldown will become cold when the given duration has passed.

While a cooldown is paused, the remaining time doesn't change.

At any time, the cooldown can be reset to its initial or a new value.

A cooldown can be compared to int/float/bool, in which case the remaining property is used.

Cooldown provides a "copy constructor", meaning you can initialize a new cooldown with an existing one. The full state of the initial cooldown is used, including paused, wrap, and the remaining time.

When a cooldown is reset, depending on when you checked the cold state, more time may have passed than the actual cooldown duration.

The wrap attribute decides, if the cooldown then is just reset back to the duration, or if this additional time is taken into account. The wrap argument of the reset function overwrites the default configuration of the cooldown instance.

c0 = Cooldown(5)
c1 = Cooldown(5, wrap=True)
sleep(7)
c0.temperature, c1.temperature
    --> -2.000088164 -2.0000879129999998

c0.reset()
c1.reset()
c0.temperature, c1.temperature
    --> 4.999999539 2.999883194

sleep(7)
c0.temperature, c1.temperature
    --> -2.000189442 -4.000306759000001

c0.reset(wrap=True)
c1.reset(wrap=False)
c0.temperature, c1.temperature
    --> 2.999748423 4.999999169

IMPORTANT: wrapping is meant to keep precise timing over a long period of time, while dealing with load peaks. If you constantly overshoot, you won't be able to catch back up to the full cooldown time. Your overshoot errors will accumulate.

A cooldown can be used as an iterator, returning the time remaining.

for t in Cooldown(5):
    print(t)
    sleep(1)

4.998921067
3.998788201
2.998640238
1.9984825379999993
0.998318566

Arguments

duration: float | pgcooldown.Cooldown

Time to cooldown in seconds

cold: bool = False

Start the cooldown already cold, e.g. for initial events.

paused: bool = False

Created the cooldown in paused state. Use cooldown.start() to run it.

wrap: bool = False

Set the reset mode to wrapped (see above). Can be overwritten by the wrap argument to the reset function.

Attributes

All attributes are read/write.

duration: float

When calling reset, the cooldown is set to this value. Can be assigned to directly or by calling cooldown.reset(duration)

temperature: float

The time left (or passed) until cooldown. Will go negative once the cooldown time has passed.

remaining: float

Same as temperature, but will not go below 0. When assigning, a negative value will be reset to 0.

normalized: float

returns the current "distance" in the cooldown between 0 and 1, with one being cold. Ideal for being used in an easing function or lerp.

paused: bool

to check if the cooldown is paused. Alternatively use cooldown.pause()/.start()/.is_paused() if you prefer methods.

wrap: bool

Activate or deactivate wrap mode.

Methods

Cooldown provides a __repr__, the comparism methods <, <=, ==, >=, >, can be converted to float/int/bool, and can be used as an iterator. The 'temperature' value is used for all operations, so results can be negative. As an iterator, StopIteration is raised when the temperature goes below 0 though.

cold(): bool

Has the time of the cooldown run out?

hot(): bool

Is there stil time remaining before cooldown? This is just for convenience to not write not cooldown.cold() all over the place.

reset([new-duration], *, wrap=bool):

Resets the cooldown. Without argument, resets to the current duration, otherwise the given value. See wrap for nuance.

reset() return self, so it can e.g. be chained with pause()

pause(), start(), is_paused():

Pause, start, check the cooldown. Time is frozen during the pause.

set_to(val):

Same as cooldown.temperature = val.

set_cold():

Same as cooldown.temperature = 0.

LerpThing

lt = LerpThing(vt0=32, vt1=175, duration=10, repeat=2)
sleep(1)
value = lt()

A time based generic gauge that lerps between 2 points.

This class can be used for scaling, color shifts, momentum, ... It gets initialized with 2 Values for t0 and t1, and a time duration, then it lerps between these values.

Once the time runs out, the lerp can stop, repeat from start or bounce back and forth.

Note: if the lerp does not repeat, in contrast to e.g. python's range function, LerpThing will not stop short of the final value, but will include it once the time has run out.

An optional easing function can be put on top of t.

LerpThing is both iterable and an iterator.

Parameters

vt0, vt1: float

The endpoints of the lerp at t == 0 and t == 1

duration: Cooldown(1)

The length of the lerp. This duration is mapped onto the range 0 - 1 as t.

This is a Cooldown object, so all configuration and query options apply, if you want to modify the lerp during its runtime.

Note: If duration is 0, vt0 is always returned.

ease: callable = lambda x: x

An optional easing function to put over t

repeat: int = 0

After the duration has passed, how to proceed?

0: Don't repeat, just stop transmogrifying 1: Reset and repeat from start 2: Bounce back and forth. Note, that bounce back is implemented by swapping vt0 and vt1.

LerpThing.finished(self)

Just a conveninence wrapper for LerpThing.duration.cold()

AutoLerpThing

my_class_attribute = AutoLerpThing()

A descriptor class for LerpThing.

If an attribute in your class could either be a constant value, or a LerpThing, use this descriptor to automatically handle this.

Note: This is a proof of concept. This might or might not stay in here, the interface might or might not change. I'm not sure if this has any advantages over a property, except not having so much boilerplate in your class if you have multiple LerpThings in it.

Note 2: In contrast to a normal LerpThing, you access the AutoLerpThing like a normal attribute, not like a method call.

Use it like this:

class Asteroid:
    angle = AutoLerpThing()

    def __init__(self):
        self.angle = (0, 360, 10)  # Will do one full rotation over 10 seconds

asteroid = Asteroid()
asteroid.angle
    --> 107.43224363999998
asteroid.angle
    --> 129.791468736
...

CronD, Cronjob

crond = CronD()

A job manager class.

In the spirit of unix's crond, this class can be used to run functions after a cooldown once or repeatedly. See CronJob below for how and why to use it.

Methods

CronD.update()

Check for due jobs and run them.

CronD.add(cooldown, task, repeat=False)

Schedule a new task.

The cooldown can be either a Cooldown object or a float representing the number of seconds.

The task is a zero parameter callback function that is called once the cooldown is cold.

repeat (bool, default is False) decides if the cooldown will reset and the task will run on repeat, or if the job is a one shot that will be removed.

A job id is returned, which can be e.g. used to remove a pending or repeating job.

CronD.remove(id)

Remove the scheduled job with the given id.

Installation

The project home is https://github.com/dickerdackel/pgcooldown

Installing HEAD from github directly

pip install git+https://github.com/dickerdackel/pgcooldown

Getting it from pypi

pip install pgcooldown

Tarball from github

Found at https://github.com/dickerdackel/pgcooldown/releases

Licensing stuff

This lib is under the MIT license.