下面是一个旋转的动力皮蒙克物体，里面有一个质量。动画开始播放后，有没有办法获取“body_type”顶部水平部分的中点。最初，我感兴趣的动体上的点的坐标为 (400,500)。旋转开始后如何打印相关点的更新坐标import pymunkimport pymunk.pygame_utilimport pygameGRAY = (220, 220, 220)width_mass=50height_mass=50pygame.init()size = 800,600screen = pygame.display.set_mode(size)draw_options = pymunk.pygame_util.DrawOptions(screen)space = pymunk.Space()space.gravity = (0,-50)pts = [(-27, -238.5), (27,-238.5), (27,238.5), (-27,238.5)]body_type=pymunk.Body(body_type=pymunk.Body.KINEMATIC) body_type.position = (400, 263.5) space.add(body_type)for i in range(4): segment = pymunk.Segment(body_type, pts[i], pts[(i+1)%4], 2) segment.elasticity = 0 segment.friction=0 space.add(segment)body_type.angular_velocity=1body = pymunk.Body(mass=1, moment=100)body.position = 400,400mass = pymunk.Poly.create_box(body, (width_mass, height_mass))mass.elasticity = 0space.add(body, mass)running = Truewhile running: for event in pygame.event.get(): if event.type == pygame.QUIT: running = False #pygame.image.save(screen, 'intro1.png') screen.fill(GRAY) space.debug_draw(draw_options) pygame.display.update() space.step(0.01)
2 回答
湖上湖
TA贡献2003条经验 获得超2个赞
a 的当前位置Body存储在position属性中（例如space.bodies[0].position）。
PyGame 使用左上角为 (0, 0) 的坐标系。y 轴需要反转 ( screen.get_height() - pos[1])，因为 y 轴一般指向上，但在 PyGame 坐标系中 y 轴指向下。
running = True
while running:
# [...]
# draw a dot in at the center of the bodies
for body in space.bodies:
pos = body.position
pygame.draw.circle(screen, (255,0,0), (pos[0], screen.get_height()-pos[1]), 7)
pygame.display.update()
space.step(0.01)
a 的当前角度Body存储在angle属性中（例如body_type.angle）。
可以通过将旋转的相对位置与绝对位置相加来计算点的当前位置。旋转位置可以通过简单的三角函数计算：
pos = abs_pos[0] + rel_dist * math.cos(angle), abs_pos[1] + rel_dist * math.sin(angle)
首先，您必须根据相对笛卡尔坐标计算相对极坐标：
rel_pos = (0, 238.5) rel_dist, rel_angle = math.hypot(*rel_pos), math.atan2(rel_pos[1], rel_pos[0])
将当前角度添加到极坐标角度：
angle = rel_angle + body_type.angle
例如：
running = True
while running:
# [...]
abs_pos = body_type.position
rel_pos = (0, 238.5)
rel_dist, rel_angle = math.hypot(*rel_pos), math.atan2(rel_pos[1], rel_pos[0])
angle = rel_angle + body_type.angle
pos = abs_pos[0] + rel_dist * math.cos(angle), abs_pos[1] + rel_dist * math.sin(angle)
pygame.draw.circle(screen, (255, 255, 0), (pos[0], screen.get_height() - pos[1]), 7)
pygame.display.update()
space.step(0.01)
最小的例子：
import pymunk
import pymunk.pygame_util
import pygame
import math
GRAY = (220, 220, 220)
width_mass=50
height_mass=50
pygame.init()
size = 800,600
screen = pygame.display.set_mode(size)
draw_options = pymunk.pygame_util.DrawOptions(screen)
space = pymunk.Space()
space.gravity = (0,-50)
pts = [(-27, -238.5), (27,-238.5), (27,238.5), (-27,238.5)]
body_type=pymunk.Body(body_type=pymunk.Body.KINEMATIC)
body_type.position = (400, 263.5)
space.add(body_type)
for i in range(4):
segment = pymunk.Segment(body_type, pts[i], pts[(i+1)%4], 2)
segment.elasticity = 0
segment.friction=0
space.add(segment)
body_type.angular_velocity=0.5
body = pymunk.Body(mass=1, moment=100)
body.position = 400,400
mass = pymunk.Poly.create_box(body, (width_mass, height_mass))
mass.elasticity = 0
space.add(body, mass)
running = True
while running:
for event in pygame.event.get():
if event.type == pygame.QUIT:
running = False
#pygame.image.save(screen, 'intro1.png')
screen.fill(GRAY)
space.debug_draw(draw_options)
for body in space.bodies:
pos = body.position
pygame.draw.circle(screen, (255, 0, 0), (pos[0], screen.get_height() - pos[1]), 7)
abs_pos = body_type.position
rel_pos = (0, 238.5)
rel_dist, rel_angle = math.hypot(*rel_pos), math.atan2(rel_pos[1], rel_pos[0])
angle = rel_angle + body_type.angle
print( body_type.position.angle)
pos = abs_pos[0] + rel_dist * math.cos(angle), abs_pos[1] + rel_dist * math.sin(angle)
pygame.draw.circle(screen, (255, 255, 0), (pos[0], screen.get_height() - pos[1]), 7)
pygame.display.update()
space.step(0.01)
汪汪一只猫
TA贡献1898条经验 获得超8个赞
使 Pymunk 模拟的行为类似于本机 PyGame 坐标。您只需将以下行添加到您的代码中即可。
pygame.pygame_util.positive_y_is_up = True
自 PyMunk 6.0 起已默认为 True。
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