How to implement a timeout/cooldown after collisio

2019-02-25 17:42发布

站内文章 / Python
18 0 0

问题:

I have been making a pygame game where two players try and hit a ball into a net. I have a boost feature in my game, however, I want some boost pads where when they are collected, I get +3 boost. In my code below, there is a huge yellow one, when someone hovers over it, they get the boost but they can stay on it forever and get lots of boost. I would like a way where the boost pad becomes inactive for 3 seconds once it has been collected, and turns grey. Is there any way for this?

import pygame
from pygame.math import Vector2
import time, datetime
import sys

pygame.font.init()
pygame.init()

WIDTH = 1150
HEIGHT = 800
screen = pygame.display.set_mode((WIDTH, HEIGHT))
clock = pygame.time.Clock()

REDCAR_ORIGINAL = pygame.Surface((50, 30), pygame.SRCALPHA)
pygame.draw.polygon(
    REDCAR_ORIGINAL, (255, 0, 0), [(0, 30), (50, 20), (50, 10), (0, 0)])
redangle = 180
redcar = pygame.transform.rotate(REDCAR_ORIGINAL, redangle)
redangle = 180
booster = pygame.Surface((50, 150), pygame.SRCALPHA)
booster.fill((255, 255, 0))
booster1 = booster.get_rect(topleft=(0, 340))
boostermask = pygame.mask.from_surface(booster)

redspeed = 5

dx = 0
dy = 0
x = 800
y = 500
redscore = 0

pos_red = Vector2(x,y)
vel_red = Vector2(-redspeed,0)
redrect = redcar.get_rect(center=pos_red)
redangle = 180
redcar = pygame.transform.rotate(REDCAR_ORIGINAL, redangle)
pos_blue = Vector2(275,300)

# Masks.
mask_red = pygame.mask.from_surface(redcar)

def redboosts():
    global vel_red
    global timer
    global dt
    if timer > 0:
        vel_red.scale_to_length(10)
        timer -= dt

def slowdown():
    vel_red.scale_to_length(5)

timer = 3
dt = 1

run = True
while run:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False
        elif event.type == pygame.KEYDOWN:
          if event.key == pygame.K_r:
              # Reset the car to the start position.
              redangle = 180
              redcar = pygame.transform.rotate(REDCAR_ORIGINAL, redangle)
              pos_red = Vector2(800, 500)
              vel_red = Vector2(-redspeed, 0)
              redrect = redcar.get_rect(center=pos_red)
              mask_red = pygame.mask.from_surface(redcar)
          #elif event.key == pygame.K_s:
          #    vel_blue.scale_to_length(2)
        elif event.type == pygame.KEYUP:
            if event.key == pygame.K_UP:
                vel_red.scale_to_length(5)
            elif event.key == pygame.K_DOWN:
              vel_red.scale_to_length(5)

    print(timer)

    keys = pygame.key.get_pressed()
    if keys[pygame.K_LEFT]:
              redangle += 5
              vel_red.rotate_ip(-5)
              redcar = pygame.transform.rotate(REDCAR_ORIGINAL, redangle)
              redrect = redcar.get_rect(center=redrect.center)
              # We need a new mask after the rotation.
              mask_red = pygame.mask.from_surface(redcar)
    elif keys[pygame.K_RIGHT]:
              redangle -= 5
              vel_red.rotate_ip(5)
              redcar = pygame.transform.rotate(REDCAR_ORIGINAL, redangle)
              redrect = redcar.get_rect(center=redrect.center)
              mask_red = pygame.mask.from_surface(redcar)

    if keys[pygame.K_UP]:
              redboosts()
    if keys[pygame.K_DOWN]:
              vel_red.scale_to_length(2)
    if keys[pygame.K_s]:
              vel_blue.scale_to_length(2)

    if y <0:
        y = 10
    if y > 450:
        y = 440
    if x > 480:
        x = 470

    if redrect.top < 0 and vel_red.y < 0:
        redrect.top = 0
        pos_red = Vector2(redrect.center)
    elif redrect.bottom > screen.get_height() and vel_red.y > 0:
        redrect.bottom = screen.get_height()
        pos_red = Vector2(redrect.center)
    if redrect.left < 0 and vel_red.x < 0:
        redrect.left = 0
        pos_red = Vector2(redrect.center)
    elif redrect.right > screen.get_width() and vel_red.x > 0:
        redrect.right = screen.get_width()
        pos_red = Vector2(redrect.center)

    pos_red += vel_red
    redrect.center = pos_red

    offset = booster1[0] - redrect[0], booster1[1] - redrect[1]
    collectboost = mask_red.overlap(boostermask, offset)

    if timer <= 0:
        timer = 0
        vel_red.scale_to_length(5)
        slowdown()

    if collectboost:
        timer += 3
    screen.fill((50,200,50))
    screen.blit(redcar, redrect)
    screen.blit(booster, booster1)

    pygame.display.flip()
    dt = clock.tick(120)/1000
pygame.quit()

回答1:

Not bad, but let's use some object oriented programming to tidy up the code a bit. That means grouping data structures and behviour and making use of polymorphism. So since we use pygame, let's use its Sprite class, but let's ignore the boosting stuff for now.

I added some comments for explanation.

import pygame
from pygame.math import Vector2
import time, datetime
import sys

pygame.font.init()
pygame.init()

WIDTH = 1150
HEIGHT = 800
screen = pygame.display.set_mode((WIDTH, HEIGHT))
clock = pygame.time.Clock()

REDCAR_ORIGINAL = pygame.Surface((50, 30), pygame.SRCALPHA)
pygame.draw.polygon(REDCAR_ORIGINAL, (255, 0, 0), [(0, 30), (50, 20), (50, 10), (0, 0)])

# Everything car related goes into this class
class Car(pygame.sprite.Sprite):
    def __init__(self):
        super().__init__()
        self.speed = 5
        # since we want to reset the car on a press of a button, 
        # let's have a reset function so we don't have duplicate code
        self.reset()

    def reset(self):
        self.angle = 180
        self.vel = Vector2(-self.speed, 0)
        self.update_image((800, 500))

    def update_image(self, center):
        # since we update the image, rect and mask a lot, 
        # let's do this in a function, also
        self.image = pygame.transform.rotate(REDCAR_ORIGINAL, self.angle)
        self.rect = self.image.get_rect(center=center)
        self.mask = pygame.mask.from_surface(self.image)

    def update(self):
        # basic input handling
        keys = pygame.key.get_pressed()
        if keys[pygame.K_LEFT]:
              self.angle += 5
              self.vel.rotate_ip(-5)
        elif keys[pygame.K_RIGHT]:
              self.angle -= 5
              self.vel.rotate_ip(5)

        self.update_image(self.rect.center)

        # ensure the car does not go out of screen
        self.rect.move_ip(self.vel)
        self.rect.clamp_ip(pygame.display.get_surface().get_rect())

red_car = Car()
all_sprites = pygame.sprite.Group(red_car)

run = True
while run:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False
        elif event.type == pygame.KEYDOWN:
          if event.key == pygame.K_r:
              red_car.reset()

    # clean little main loop, yeah
    all_sprites.update()

    screen.fill((50,200,50))

    all_sprites.draw(screen)

    pygame.display.flip()
    dt = clock.tick(120)/1000

pygame.quit()

Now that this works, let's at the Boost class. Since we use classes, it's easy to add multiple ones. Each one has its own state; we use simple substraction to implement the timeout:

import pygame
from pygame.math import Vector2
import time, datetime
import sys
import pygame.freetype

pygame.font.init()
pygame.init()

WIDTH = 1150
HEIGHT = 800
screen = pygame.display.set_mode((WIDTH, HEIGHT))
clock = pygame.time.Clock()

REDCAR_ORIGINAL = pygame.Surface((50, 30), pygame.SRCALPHA)
pygame.draw.polygon(REDCAR_ORIGINAL, (255, 0, 0), [(0, 30), (50, 20), (50, 10), (0, 0)])

FONT = pygame.freetype.SysFont(None, 34)

# Everything car related goes into this class
class Car(pygame.sprite.Sprite):
    def __init__(self):
        super().__init__()
        self.speed = 3
        # since we want to reset the car on a press of a button, 
        # let's have a reset function so we don't have duplicate code
        self.reset()

    def reset(self):
        # if boost is > 0, we can drive faster
        self.boost = 0
        self.angle = 180
        self.vel = Vector2(-self.speed, 0)
        self.update_image((800, 500))

    def update_image(self, center):
        # since we update the image, rect and mask a lot, 
        # let's do this in a function, also
        self.image = pygame.transform.rotate(REDCAR_ORIGINAL, self.angle)
        self.rect = self.image.get_rect(center=center)
        self.mask = pygame.mask.from_surface(self.image)

    def update(self, dt):

        if self.boost > 0:
            self.boost -= dt
        if self.boost < 0:
            self.boost = 0

        # basic input handling
        keys = pygame.key.get_pressed()
        if keys[pygame.K_LEFT]:
              self.angle += 5
              self.vel.rotate_ip(-5)
        elif keys[pygame.K_RIGHT]:
              self.angle -= 5
              self.vel.rotate_ip(5)

        self.update_image(self.rect.center)

        # double the speed if we have boost
        self.rect.move_ip(self.vel * (2 if self.boost else 1))

        # ensure the car does not go out of screen
        self.rect.clamp_ip(pygame.display.get_surface().get_rect())

class Booster(pygame.sprite.Sprite):
    def __init__(self, rect, cars):
        super().__init__()
        rect = pygame.rect.Rect(rect)
        # a simple timeout. We do nothing if timeout > 0
        self.timeout = 0
        self.image = pygame.Surface(rect.size, pygame.SRCALPHA)
        self.image.fill(pygame.color.Color('yellow'))
        self.rect = rect
        self.mask = pygame.mask.from_surface(self.image)
        self.cars = cars

    def update(self, dt):
        disabled = self.timeout > 0

        if disabled:
            self.timeout -= dt
            self.image.fill(pygame.color.Color('grey'))
            FONT.render_to(self.image, (10, 10), str((self.timeout // 1000) + 1), pygame.color.Color('white'))

        if self.timeout < 0:
            self.timeout = 0

        if disabled and self.timeout == 0:
            # let's reactive
            self.image.fill(pygame.color.Color('yellow'))
        if not disabled:
            for car in pygame.sprite.spritecollide(self, self.cars, False, pygame.sprite.collide_mask):
                # let's boost the car
                car.boost += 1000
                # let's deactivate
                self.timeout = 3000
                break

red_car = Car()
cars = pygame.sprite.Group(red_car)
all_sprites = pygame.sprite.OrderedUpdates()

# see how easy it is now to create multiple Booster
for r in [(0, 340, 50, 150), (200, 200, 150, 50), (600, 600, 100, 100)]:
    all_sprites.add(Booster(r, cars))

all_sprites.add(red_car)

dt = 0
run = True
while run:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False
        elif event.type == pygame.KEYDOWN:
          if event.key == pygame.K_r:
              red_car.reset()

    # clean little main loop, yeah
    all_sprites.update(dt)

    screen.fill((50,200,50))

    all_sprites.draw(screen)

    pygame.display.flip()
    dt = clock.tick(120)

pygame.quit()

Each Booster has a timeout of 3 seconds, and it boosts for 1 second.

We make use of OrderedUpdates to draw our sprites in the right order, and spritecollide and collide_mask for the collision detection.

Here's a shitty gif of our little game in action:



标签： python python-3.x pygame
举报

收藏的人(0)

Ta的文章 更多文章
登录 后发表评论
0条评论
还没有人评论过~