pygame 笔记-6 碰撞检测

这一节学习碰撞检测，先看原理图：

2个矩形如果发生碰撞(即：图形有重叠区域)，按上图的判断条件就能检测出来，如果是圆形，则稍微变通一下，用半径检测。如果是其它不规则图形，大多数游戏中，并不要求精确检测，可以在外层套一个矩形，大致用上图的原理检测。

可以封装一个函数：

def collision_check(a, b):
    temp1 = (b.x <= a.x + a.width <= b.x + b.width)
    temp2 = (b.y <= a.y + a.height <= b.y + b.height)
    return temp1 and temp2

要注意的是：矩形A，B碰撞时，有可能是A撞B，也有可能是B撞A，所以使用上面的函数时，最好写好 if collision_check(a,b) or collision_check(b,a):

为了方便观察，我们在上节的3个类文件（即：Player、Enemy、Bullet)里，略做修改，手动在外层套一个矩形（hit_box)

import pygame

# 主角
class Player(object):

    def __init__(self, x, y, width, height, img_base_path):
        self.x = x
        self.y = y
        self.width = width
        self.height = height
        self.speed = 5
        self.left = False
        self.right = True
        self.isJump = False
        self.walkCount = 0
        self.t = 10
        self.speed = 5
        self.char = pygame.image.load(img_base_path + 'standing.png')
        self.walkRight = [pygame.image.load(img_base_path + 'actor/R1.png'),
                          pygame.image.load(img_base_path + 'actor/R2.png'),
                          pygame.image.load(img_base_path + 'actor/R3.png'),
                          pygame.image.load(img_base_path + 'actor/R4.png'),
                          pygame.image.load(img_base_path + 'actor/R5.png'),
                          pygame.image.load(img_base_path + 'actor/R6.png'),
                          pygame.image.load(img_base_path + 'actor/R7.png'),
                          pygame.image.load(img_base_path + 'actor/R8.png'),
                          pygame.image.load(img_base_path + 'actor/R9.png')]

        self.walkLeft = [pygame.image.load(img_base_path + 'actor/L1.png'),
                         pygame.image.load(img_base_path + 'actor/L2.png'),
                         pygame.image.load(img_base_path + 'actor/L3.png'),
                         pygame.image.load(img_base_path + 'actor/L4.png'),
                         pygame.image.load(img_base_path + 'actor/L5.png'),
                         pygame.image.load(img_base_path + 'actor/L6.png'),
                         pygame.image.load(img_base_path + 'actor/L7.png'),
                         pygame.image.load(img_base_path + 'actor/L8.png'),
                         pygame.image.load(img_base_path + 'actor/L9.png')]
        self.hit_box = (self.x + 17, self.y + 11, 29, 52)

    def draw(self, win):
        if self.walkCount >= 9:
            self.walkCount = 0

        if self.left:
            win.blit(self.walkLeft[self.walkCount % 9], (self.x, self.y))
            self.walkCount += 1
        elif self.right:
            win.blit(self.walkRight[self.walkCount % 9], (self.x, self.y))
            self.walkCount += 1
        else:
            win.blit(self.char, (self.x, self.y))
        # 碰撞检测框
        self.hit_box = (self.x + 17, self.y + 11, 29, 52)
        pygame.draw.rect(win, (255, 0, 0), self.hit_box, 2)

Enemy类：

import pygame

class Enemy(object):

    def __init__(self, x, y, width, height, end, img_base_path):
        self.x = x
        self.y = y
        self.width = width
        self.height = height
        self.path = [x, end]
        self.walkCount = 0
        self.vel = 3
        self.walkRight = [pygame.image.load(img_base_path + 'enemy/R1E.png'),
                          pygame.image.load(img_base_path + 'enemy/R2E.png'),
                          pygame.image.load(img_base_path + 'enemy/R3E.png'),
                          pygame.image.load(img_base_path + 'enemy/R4E.png'),
                          pygame.image.load(img_base_path + 'enemy/R5E.png'),
                          pygame.image.load(img_base_path + 'enemy/R6E.png'),
                          pygame.image.load(img_base_path + 'enemy/R7E.png'),
                          pygame.image.load(img_base_path + 'enemy/R8E.png'),
                          pygame.image.load(img_base_path + 'enemy/R9E.png'),
                          pygame.image.load(img_base_path + 'enemy/R10E.png'),
                          pygame.image.load(img_base_path + 'enemy/R11E.png')]

        self.walkLeft = [pygame.image.load(img_base_path + 'enemy/L1E.png'),
                         pygame.image.load(img_base_path + 'enemy/L2E.png'),
                         pygame.image.load(img_base_path + 'enemy/L3E.png'),
                         pygame.image.load(img_base_path + 'enemy/L4E.png'),
                         pygame.image.load(img_base_path + 'enemy/L5E.png'),
                         pygame.image.load(img_base_path + 'enemy/L6E.png'),
                         pygame.image.load(img_base_path + 'enemy/L7E.png'),
                         pygame.image.load(img_base_path + 'enemy/L8E.png'),
                         pygame.image.load(img_base_path + 'enemy/L9E.png'),
                         pygame.image.load(img_base_path + 'enemy/L10E.png'),
                         pygame.image.load(img_base_path + 'enemy/L11E.png')]
        self.hit_box = (self.x + 17, self.y + 2, 31, 57)

    def draw(self, win):
        self.move()
        if self.walkCount >= 11:
            self.walkCount = 0

        if self.vel > 0:
            win.blit(self.walkRight[self.walkCount % 11], (self.x, self.y))
            self.walkCount += 1
        else:
            win.blit(self.walkLeft[self.walkCount % 11], (self.x, self.y))
            self.walkCount += 1
        # 碰撞检测框
        self.hit_box = (self.x + 17, self.y + 2, 31, 57)
        pygame.draw.rect(win, (255, 0, 0), self.hit_box, 2)

    def move(self):
        if self.vel > 0:
            if self.x < self.path[1] + self.vel:
                self.x += self.vel
            else:
                self.vel = self.vel * -1
                self.x += self.vel
                self.walkCount = 0
        else:
            if self.x > self.path[0] - self.vel:
                self.x += self.vel
            else:
                self.vel = self.vel * -1
                self.x += self.vel
                self.walkCount = 0

以及子弹类：

import pygame

# 子弹类
class Bullet(object):

    def __init__(self, x, y, direction, img_base_path):
        self.x = x
        self.y = y
        self.direction = direction
        self.vel = 8 * direction
        self.width = 24
        self.height = 6
        self.bullet_right = pygame.image.load(img_base_path + 'r_bullet.png')
        self.bullet_left = pygame.image.load(img_base_path + 'l_bullet.png')
        self.hit_box = (self.x + 17, self.y + 11, 24, 6)

    def draw(self, win):
        # 根据人物行进的方向，切换不同的子弹图片
        if self.direction == -1:
            win.blit(self.bullet_left, (self.x - 35, self.y))
            # 碰撞检测框
            self.hit_box = (self.x - 38, self.y + 1, 24, 6)
        else:
            win.blit(self.bullet_right, (self.x + 10, self.y))
            # 碰撞检测框
            self.hit_box = (self.x + 10, self.y + 1, 24, 6)
        pygame.draw.rect(win, (255, 0, 0), self.hit_box, 2)

这样处理后，运动起来的样子如下：

最后主文件中，加入碰撞检测代码：

import os
from bullet import *
from player import *
from enemy import *

WIN_WIDTH, WIN_HEIGHT = 500, 500
pygame.init()
win = pygame.display.set_mode((WIN_WIDTH, WIN_HEIGHT))
pygame.display.set_caption("first game")
img_base_path = os.getcwd() + '/img/'
bg = pygame.image.load(img_base_path + 'bg.jpg')

clock = pygame.time.Clock()

def redraw_game_window():
    win.blit(bg, (0, 0))
    # 显示击中后的得分
    text = font.render('Score: ' + str(score), 1, (0, 0, 0))
    win.blit(text, (370, 10))
    man.draw(win)
    enemy.draw(win)
    for bullet in bullets:
        bullet.draw(win)
    pygame.display.update()

def collision_check(a, b):
    temp1 = (b.x <= a.x + a.width <= b.x + b.width)
    temp2 = (b.y <= a.y + a.height <= b.y + b.height)
    return temp1 and temp2

# main
font = pygame.font.SysFont('comicsans', 30, True)
man = Player(200, 410, 64, 64, img_base_path)
enemy = Enemy(100, 414, 64, 64, 400, img_base_path)
run = True
score = 0
bullets = []
while run:
    clock.tick(27)

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False

    for b in bullets:
        # 碰撞检测
        if collision_check(b, enemy) or collision_check(enemy, b):
            score += 1
            bullets.pop(bullets.index(b))

        if WIN_WIDTH > b.x > 0:
            b.x += b.vel
        else:
            bullets.pop(bullets.index(b))

    keys = pygame.key.get_pressed()

    if keys[pygame.K_SPACE]:
        if man.left:
            direction = -1
        else:
            direction = 1

        if len(bullets) < 5:
            bullets.append(Bullet(man.x + man.width // 2, man.y + man.height // 2, direction, img_base_path))

    if keys[pygame.K_LEFT] and man.x > 0:
        man.x -= man.speed
        man.left = True
        man.right = False
    elif keys[pygame.K_RIGHT] and man.x < win.get_size()[0] - man.width:
        man.x += man.speed
        man.left = False
        man.right = True
    else:
        man.walkCount = 0

    if not man.isJump:
        if keys[pygame.K_UP]:
            man.isJump = True
            man.walkCount = 0
    else:
        if man.t >= -10:
            a = 1
            if man.t < 0:
                a = -1
            man.y -= 0.5 * a * (man.t ** 2)

            man.t -= 1
        else:
            man.isJump = False
            man.t = 10

    redraw_game_window()

pygame.quit()

源码下载： https://github.com/yjmyzz/pygame_tutorial