我一直在做一个pygame游戏，其中2辆汽车在一个球场上击球。当运动员与球碰撞时，球会向前移动，但是，如果运动员的底部碰到球的顶部，则球仍会向上运动，因为代码会告诉球接触后向上运动。但是，我希望当球被向下击时，球实际向下运动。有人知道吗？
import pygame as pg
from pygame.math import Vector2
pg.init()
LIGHTBLUE = pg.Color('lightskyblue2')
DARKBLUE = pg.Color(11, 8, 69)
screen = pg.display.set_mode((800, 600))
width, height = screen.get_size()
clock = pg.time.Clock()
# You need surfaces with an alpha channel for the masks.
bluecar = pg.Surface((60, 30), pg.SRCALPHA)
bluecar.fill((0,0,255))
BALL = pg.Surface((30, 30), pg.SRCALPHA)
pg.draw.circle(BALL, [0,0,0], [15, 15], 15)
ball_pos = Vector2(395, 15)
ballrect = BALL.get_rect(center=ball_pos)
ball_vel = Vector2(0, 0)
mask_blue = pg.mask.from_surface(bluecar)
mask_ball = pg.mask.from_surface(BALL)
pos_blue = Vector2(740, 500) # Just use the pos vector instead of x, y.
bluerect = bluecar.get_rect(center = pos_blue)
vel_blue = Vector2(0, 0) # Replace x_change, y_change with vel_blue.
# A constant value that you add to the y-velocity each frame.
GRAVITY = .5
ground_y = height - 100
timer = 3
dt = 1
def bluejumps():
if timer > 0:
vel_blue.y = -12
if pos_blue.y > 469:
timer -= dt
done = False
while not done:
for event in pg.event.get():
if event.type == pg.QUIT:
done = True
elif event.type == pg.KEYDOWN:
if event.key == pg.K_a:
vel_blue.x = -5
elif event.key == pg.K_d:
vel_blue.x = 5
elif event.key == pg.K_w:
bluejumps()
elif event.type == pg.KEYUP:
if event.key == pg.K_a and vel_blue.x < 0:
vel_blue.x = 0
elif event.key == pg.K_d and vel_blue.x > 0:
vel_blue.x = 0
if bluerect.bottom >= ground_y:
bluerect.bottom = ground_y
pos_blue.y = bluerect.centery
#vel_blue.y = 0
timer = 3
ball_vel.y += GRAVITY # Accelerate downwards.
ball_pos += ball_vel # Move the ball.
ballrect.center = ball_pos # Update the rect.
# Bounce when the ball touches the bottom of the screen.
if ballrect.bottom >= ground_y:
# Just invert the y-velocity to bounce.
ball_vel.y *= -0.7 # Change this value to adjust the elasticity.
ball_vel.x *= .95 # Friction
# Don't go below the ground.
ballrect.bottom = ground_y
ball_pos.y = ballrect.centery
# Left and right wall collisions.
if ballrect.left < 0:
ball_vel.x *= -1
ballrect.left = 0
ball_pos.x = ballrect.centerx
elif ballrect.right > width:
ball_vel.x *= -1
ballrect.right = width
ball_pos.x = ballrect.centerx
if ballrect.top <= 0:
# Just invert the y-velocity to bounce.
ball_vel.y *= -0.4 # Change this value to adjust the elasticity.
ballrect.top = 1
ball_pos.y = ballrect.centery
# Add the GRAVITY value to vel_blue.y, so that
# the object moves faster each frame.
vel_blue.y += GRAVITY
pos_blue += vel_blue
bluerect.center = pos_blue # You have to update the rect as well.
# Stop the object when it's near the bottom of the screen.
if bluerect.bottom >= ground_y:
bluerect.bottom = ground_y
pos_blue.y = bluerect.centery
vel_blue.y = 0
timer = 3
if bluerect.x < 0:
bluerect.x = 0
pos_blue.x = bluerect.centerx
elif bluerect.right > width:
bluerect.right = width
pos_blue.x = bluerect.centerx
print(timer)
offset_blue = bluerect[0] - ballrect[0], bluerect[1] - ballrect[1]
overlap_blue = mask_ball.overlap(mask_blue, offset_blue)
if overlap_blue: # Blue collides with the ball.
if vel_blue.x != 0: # Player is moving.
ball_vel = Vector2(vel_blue.x, -17)
else: # If the player is standing, I just update the vel.y.
ball_vel.y = -17
# Draw everything.
screen.fill(LIGHTBLUE)
pg.draw.line(screen, (0, 0, 0), (0, ground_y), (width, ground_y))
screen.blit(bluecar, bluerect) # Blit it at the rect.
screen.blit(BALL, ballrect)
pg.display.update()
dt = clock.tick(60)/1000
pg.quit()
答案 0 :(得分：0)
最简单的解决方法是使玩家实际上是两个对象。如果球与上半部分相交，则使其向上反弹；如果击中下半部分，则将其向下约束。更准确的方法是计算碰撞点，并基于此方法应用一些刚体碰撞响应数学，但是这种方法可能足以满足您的情况。
仅当球的移动速度不是太快时，这种简单的方法才有用，当一次打球时球通过了大部分球员时，但是对于您的情况来说可能就足够了，您需要做一些测试以确定是否值得额外的复杂性