Question

目标是使子弹从播放器的当前位置出来，然后使其沿直线移动，该直线由矢量定义，该矢量由单击按钮时鼠标位置的点定义和播放器的位置，但是当按下按钮时什么也没发生。谁能告诉我这段代码有什么问题吗？谢谢

import pygame
import math
pygame.init()
win = pygame.display.set_mode((500,500))
pygame.display.set_caption("Space Shooter")
char = pygame.image.load("spaceship_sprite.png")

x = 500/2
y = 500/2
width = 50
height = 50
velocity = 6
list_of_bullets = []

def point_to_mouse(x,y,char):
    mouse_x, mouse_y = pygame.mouse.get_pos()
    vector_x, vector_y = mouse_x - x, mouse_y - y
    angle = (180 / math.pi) * -math.atan2(vector_y, vector_x) - 90
    updated_image = pygame.transform.rotate(char,int(angle))
    image_location = updated_image.get_rect(center= (x,y))
    win.blit(updated_image,image_location)

def update_game(x,y,width,height,char):
    win.fill((0,0,0))
    point_to_mouse(x,y,char)
    pygame.display.update()

def spawn_bullet(x,y):
    global list_of_bullets
    initial_x = x
    initial_y = y
    mouse_x, mouse_y = pygame.mouse.get_pos()
    vector_x, vector_y = mouse_x - x, mouse_y - y
    #normalize the vector
    distance = math.sqrt(vector_x ** 2 + vector_y **2)
    normalized_vec = (vector_x/ distance, vector_y/distance)
    list_of_bullets.append([initial_x,initial_y,normalized_vec])


run = True
while run:
    #check for an event
    pygame.time.delay(75)
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False
        if event.type == pygame.MOUSEBUTTONDOWN:
            spawn_bullet(x,y)

    for bullet in list_of_bullets:
        bullet[0] = bullet[0] * bullet[2][0]
        bullet[1] = bullet[1] * bullet[2][1]

        pygame.draw.rect(win,(0,0,255),(int(bullet[0]),int(bullet[1]),20,20))

        if bullet[0] > 500 or bullet[0] < 0 or bullet[1] < 0 or bullet[1] > 500:
            del list_of_bullets[list_of_bullets.index(bullet)]
            continue



    keys = pygame.key.get_pressed()
    if keys[pygame.K_LEFT] and x > 0 + width:
        x = x - velocity
    elif keys[pygame.K_RIGHT] and x < 500 - width:
        x = x + velocity
    elif keys[pygame.K_UP] and y > 0 + width:
        y = y - velocity
    elif keys[pygame.K_DOWN] and y < 500 - width:
        y = y + velocity


    update_game(x,y,width,height,char)

pygame.quit()

Answer 1

有2个问题。子弹的当前位置乘以其归一化方向矢量。那没有道理：

for bullet in list_of_bullets:
   bullet[0] = bullet[0] * bullet[2][0]
   bullet[1] = bullet[1] * bullet[2][1]

将方向矢量添加到子弹的位置：

for bullet in list_of_bullets:
    bullet[0] += bullet[2][0]
    bullet[1] += bullet[2][1]

如果要提高子弹的速度，则必须将向量缩放一定的speed。例如：

def spawn_bullet(x,y):
    global list_of_bullets
    initial_x = x
    initial_y = y
    mouse_x, mouse_y = pygame.mouse.get_pos()
    vector_x, vector_y = mouse_x - x, mouse_y - y

    distance = math.sqrt(vector_x ** 2 + vector_y **2)
    speed = 5
    move_vec = (speed*vector_x/distance, speed*vector_y/distance)

    list_of_bullets.append([initial_x, initial_y, move_vec])

第二个问题是，在抽出子弹后清除了显示内容，因此您永远不会“看到”子弹。

清除显示后，在update_game中绘制项目符号：

def update_game(x,y,width,height,char):
    win.fill((0,0,0))
    for bullet in list_of_bullets:
        pygame.draw.rect(win,(0,0,255),(int(bullet[0]),int(bullet[1]),20,20))
    point_to_mouse(x,y,char)
    pygame.display.update()

（删除主应用程序循环的图形）

为什么屏幕上没有出现任何项目符号？ -pygame

1 个答案: