用Python和Pygame写游戏-从入门到精通（10）方向移动

background_image_filename = 'sushiplate.jpg'
sprite_image_filename = 'fugu.png'

import pygame
from pygame.locals import *
from sys import exit
import vector2

pygame.init()
close = False
screen = pygame.display.set_mode((640, 480), 0, 32)

background = pygame.image.load(background_image_filename).convert()
sprite = pygame.image.load(sprite_image_filename).convert_alpha()

clock = pygame.time.Clock()

sprite_pos = vector2.Vec2d(200, 150)
sprite_speed = 300.

while True:

for event in pygame.event.get():
if event.type == QUIT:
pygame.quit()
exit
close = True

if close == True:
break

pressed_keys = pygame.key.get_pressed()

key_direction = vector2.Vec2d(0, 0)
if pressed_keys[K_LEFT]:
key_direction.x = -1
elif pressed_keys[K_RIGHT]:
key_direction.x = +1
if pressed_keys[K_UP]:
key_direction.y = -1
elif pressed_keys[K_DOWN]:
key_direction.y = +1

key_direction.normalized()

screen.blit(background, (0,0))
screen.blit(sprite, sprite_pos)

time_passed = clock.tick(30)
time_passed_seconds = time_passed / 1000.0

sprite_pos+= key_direction * sprite_speed * time_passed_seconds

pygame.display.update()

background_image_filename = 'sushiplate.jpg'
sprite_image_filename = 'fugu.png'

import pygame
from pygame.locals import *
from sys import exit
import vector2
from math import *

pygame.init()
close = False
screen = pygame.display.set_mode((640, 480), 0, 32)

background = pygame.image.load(background_image_filename).convert()
sprite = pygame.image.load(sprite_image_filename).convert_alpha()

clock = pygame.time.Clock()

sprite_pos = vector2.Vec2d(200, 150)   # 初始位置
sprite_speed = 300.     # 每秒前进的像素数（速度）
sprite_rotation = 0.      # 初始角度
sprite_rotation_speed = 360. # 每秒转动的角度数（转速）

while True:

for event in pygame.event.get():
if event.type == QUIT:
pygame.quit()
exit
close = True
if close == True:
break

pressed_keys = pygame.key.get_pressed()

rotation_direction = 0.
movement_direction = 0.

# 更改角度
if pressed_keys[K_LEFT]:
rotation_direction = +1.
if pressed_keys[K_RIGHT]:
rotation_direction = -1.
# 前进、后退
if pressed_keys[K_UP]:
movement_direction = -1.
if pressed_keys[K_DOWN]:
movement_direction = +1.

screen.blit(background, (0,0))

# 获得一条转向后的鱼
rotated_sprite = pygame.transform.rotate(sprite, sprite_rotation)
# 转向后，图片的长宽会变化，因为图片永远是矩形，为了放得下一个转向后的矩形，外接的矩形势必会比较大
w, h = rotated_sprite.get_size()
# 获得绘制图片的左上角（感谢pltc325网友的指正）
sprite_draw_pos = vector2.Vec2d(sprite_pos.x-w/2, sprite_pos.y-h/2)
screen.blit(rotated_sprite, sprite_draw_pos)

time_passed = clock.tick()
time_passed_seconds = time_passed / 1000.0

# 图片的转向速度也需要和行进速度一样，通过时间来控制
sprite_rotation += rotation_direction * sprite_rotation_speed * time_passed_seconds

# 获得前进（x方向和y方向），这两个需要一点点三角的知识
heading_x = sin(sprite_rotation*pi/180.)
heading_y = cos(sprite_rotation*pi/180.)
# 转换为单位速度向量
heading = vector2.Vec2d(heading_x, heading_y)
# 转换为速度
heading *= movement_direction

sprite_pos+= heading * sprite_speed * time_passed_seconds

pygame.display.update()