问题
could you help me with a problem I have? I am a new person with regard to programming and to guide me I am using the book: How to think like a computer scientist 3rd edition. And it could not solve exercise 2 of chapter 17. This says that an error occurs when clicking on any frame that is on the right side of the sprite, which causes the animation to start, in theory it should only do the animation if it is you click directly on the sprite, I tried to solve it in many ways but I couldn't, could you help me ?, I think the error occurs in this part
return ( x >= my_x and x + my_width and y >= my_y and y < my_y + my_height)
but I'm not sure, for anything I leave you all the code I have
import pygame
gravity = 0.025
my_clock = pygame.time.Clock()
class QueenSprite:
def __init__(self, img, target_posn):
self.image = img
self.target_posn = target_posn
(x, y) = target_posn
self.posn = (x, 0) # Start ball at top of its column
self.y_velocity = 0 # with zero initial velocity
def update(self):
self.y_velocity += gravity
(x, y) = self.posn
new_y_pos = y + self.y_velocity
(target_x, target_y) = self.target_posn # Unpack the position
dist_to_go = target_y - new_y_pos # How far to our floor?
if dist_to_go < 0: # Are we under floor?
self.y_velocity = -0.65 * self.y_velocity # Bounce
new_y_pos = target_y + dist_to_go # Move back above floor
self.posn = (x, new_y_pos) # Set our new position.
def draw(self, target_surface): # Same as before.
target_surface.blit(self.image, self.posn)
def contains_point(self, pt):
""" Return True if my sprite rectangle contains point pt """
(my_x, my_y) = self.posn
my_width = self.image.get_width()
my_height = self.image.get_height()
(x, y) = pt
return ( x >= my_x and x < my_x + my_width and
y >= my_y and y < my_y + my_height)
def handle_click(self):
self.y_velocity += -2 # Kick it up
class DukeSprite:
def __init__(self, img, target_posn):
self.image = img
self.posn = target_posn
self.anim_frame_count = 0
self.curr_patch_num = 0
def update(self):
if self.anim_frame_count > 0:
self.anim_frame_count = (self.anim_frame_count + 1 ) % 60
self.curr_patch_num = self.anim_frame_count // 6
def draw(self, target_surface):
patch_rect = (self.curr_patch_num * 50, 0,
50, self.image.get_width())
target_surface.blit(self.image, self.posn, patch_rect)
def contains_point(self, pt):
""" Return True if my sprite rectangle contains pt """
(my_x, my_y) = self.posn
my_width = self.image.get_width()
my_height = self.image.get_height()
(x, y) = pt
return ( x >= my_x and x + my_width and y >= my_y and y < my_y + my_height)
def handle_click(self):
if self.anim_frame_count == 0:
self.anim_frame_count = 5
def draw_board(the_board):
""" Draw a chess board with queens, as determined by the the_board. """
pygame.init()
colors = [(255,0,0), (0,0,0)] # Set up colors [red, black]
n = len(the_board) # This is an NxN chess board.
surface_sz = 480 # Proposed physical surface size.
sq_sz = surface_sz // n # sq_sz is length of a square.
surface_sz = n * sq_sz # Adjust to exactly fit n squares.
# Create the surface of (width, height), and its window.
surface = pygame.display.set_mode((surface_sz, surface_sz))
ball = pygame.image.load("ball.png")
# Use an extra offset to centre the ball in its square.
# If the square is too small, offset becomes negative,
# but it will still be centered :-)
ball_offset = (sq_sz-ball.get_width()) // 2
all_sprites = [] # Keep a list of all sprites in the game
# Create a sprite object for each queen, and populate our list.
for (col, row) in enumerate(the_board):
a_queen = QueenSprite(ball,
(col*sq_sz+ball_offset, row*sq_sz+ball_offset))
all_sprites.append(a_queen)
# Load the sprite sheet
duke_sprite_sheet = pygame.image.load("duke_spritesheet.png")
# Instantiate two duke instances, put them on the chessboard
duke1 = DukeSprite(duke_sprite_sheet,(sq_sz*2, 0))
duke2 = DukeSprite(duke_sprite_sheet,(sq_sz*5, sq_sz))
# Add them to the list of sprites which our game loop manages
all_sprites.append(duke1)
all_sprites.append(duke2)
while True:
# Look for an event from keyboard, mouse, etc.
ev = pygame.event.poll()
if ev.type == pygame.QUIT:
break;
if ev.type == pygame.KEYDOWN:
key = ev.dict["key"]
if key == 27: # On Escape key ...
break # leave the game loop.
if key == ord("r"):
colors[0] = (255, 0, 0) # Change to red + black.
elif key == ord("g"):
colors[0] = (0, 255, 0) # Change to green + black.
elif key == ord("b"):
colors[0] = (0, 0, 255) # Change to blue + black.
if ev.type == pygame.MOUSEBUTTONDOWN: # Mouse gone down?
posn_of_click = ev.dict["pos"] # Get the coordinates.
for sprite in all_sprites:
if sprite.contains_point(posn_of_click):
sprite.handle_click()
break
for sprite in all_sprites:
sprite.update()
# Draw a fresh background (a blank chess board)
for row in range(n): # Draw each row of the board.
c_indx = row % 2 # Alternate starting color
for col in range(n): # Run through cols drawing squares
the_square = (col*sq_sz, row*sq_sz, sq_sz, sq_sz)
surface.fill(colors[c_indx], the_square)
# Now flip the color index for the next square
c_indx = (c_indx + 1) % 2
# Ask every sprite to draw itself.
for sprite in all_sprites:
sprite.draw(surface)
my_clock.tick(60) # Waste time so that frame rate becomes 60 fps
pygame.display.flip()
pygame.quit()
if __name__ == "__main__":
draw_board([0, 5, 3, 1, 6, 4, 2]) # 7 x 7 to test window size
回答1:
There is < my_x missing in the comparisons expression in the method contains_point of the class DukeSprite:
return ( x >= my_x and x + my_width and y >= my_y and y < my_y + my_height)
return ( x >= my_x and x < my_x + my_width and y >= my_y and y < my_y + my_height)
Anyway in python you should use chained comparisons:
return my_x <= x < my_x + my_width and my_y <= y < my_y + my_height
In pygame you should use pygame.Rect and collidepoint(). The rectangle of the object you can get from the pygame.Surface with the method get_rect and the position can be set by an keyword argument:
def contains_point(self, pt):
""" Return True if my sprite rectangle contains pt """
my_rect = self.image.get_rect(topleft = self.posn)
return my_rect.collidepoint(pt)
来源：https://stackoverflow.com/questions/62975776/python-pygame-noob-question-about-animation