我想围绕一个枢轴旋转图像,该枢轴不在 Surface 的中心在 Pygame .
枢轴是图像中的绿色十字:
我知道游戏窗口中枢轴的位置。
我如何在此时跟踪图像并同时围绕该点旋转它。
image = pygame.image.load("boomerang64.png")
pos = (200, 200)
angle = 0
while True:
# [...]
rotate_rect, rotate_image = ???? # rotate around green cross by angle
surf.blit(rotated_image, rotate_rect)
angle += 1
# [...]
最佳答案
首先是 Surface
上枢轴的位置必须定义:
image = pygame.image.load("boomerang64.png") # 64x64 surface
pivot = (48, 21) # position of the pivot on the image
旋转图像时,其大小会增加。我们要比较axis aligned bounding box旋转前和旋转后的图像。对于以下数学
pygame.math.Vector2
用来。注意屏幕坐标中的 y 指向屏幕下方,但数学 y 轴点从底部到顶部。这导致在计算过程中必须“翻转”y 轴。请注意 pygame.math.Vector2.rotate
与 pygame.transform.rotate
的旋转方向相反.因此角度必须倒转。用边界框的 4 个角点设置一个列表,并将向量旋转到角点
pygame.math.Vector2.rotate
.最后找到旋转框的最小值。由于 pygame 中的 y 轴指向下方,因此必须通过找到旋转倒置高度的最大值 ("max(rotate(-h))") 来补偿:计算从图像中心到枢轴的向量:
image_rect = image.get_rect(topleft = (pos[0] - originPos[0], pos[1]-originPos[1]))
offset_center_to_pivot = pygame.math.Vector2(pos) - image_rect.center
旋转偏移向量:rotated_offset = offset_center_to_pivot.rotate(-angle)
计算旋转图像的中心:rotated_image_center = (pos[0] - rotated_offset.x, pos[1] - rotated_offset.y)
旋转和 blit 图像:rotated_image = pygame.transform.rotate(image, angle)
rotated_image_rect = rotated_image.get_rect(center = rotated_image_center)
screen.blit(rotated_image, rotated_image_rect)
在下面的示例程序中,函数 blitRotate(surf, image, pos, originPos, angle)
执行上述所有步骤和 blit
旋转到与显示器相关联的 Surface 的图像:surf
是目标曲面 image
是必须旋转的表面和 blit
pos
是目标曲面上的枢轴位置 surf
(相对于 surf
的左上角) originPos
是 image
上枢轴的位置表面(相对于 image
的左上角)angle
是以度为单位的旋转角度 import math
import pygame
def blitRotate(surf, image, pos, originPos, angle):
image_rect = image.get_rect(topleft = (pos[0] - originPos[0], pos[1]-originPos[1]))
offset_center_to_pivot = pygame.math.Vector2(pos) - image_rect.center
rotated_offset = offset_center_to_pivot.rotate(-angle)
rotated_image_center = (pos[0] - rotated_offset.x, pos[1] - rotated_offset.y)
rotated_image = pygame.transform.rotate(image, angle)
rotated_image_rect = rotated_image.get_rect(center = rotated_image_center)
surf.blit(rotated_image, rotated_image_rect)
pygame.init()
size = (400,400)
screen = pygame.display.set_mode(size)
clock = pygame.time.Clock()
image = pygame.image.load('Boomerang64.png')
pivot = (48, 21)
angle, frame = 0, 0
done = False
while not done:
clock.tick(60)
for event in pygame.event.get():
if event.type == pygame.QUIT:
done = True
screen.fill(0)
pos = (200 + math.cos(frame * 0.05)*100, 200 + math.sin(frame * 0.05)*50)
blitRotate(screen, image, pos, pivot, angle)
pygame.draw.line(screen, (0, 255, 0), (pos[0]-20, pos[1]), (pos[0]+20, pos[1]), 3)
pygame.draw.line(screen, (0, 255, 0), (pos[0], pos[1]-20), (pos[0], pos[1]+20), 3)
pygame.draw.circle(screen, (0, 255, 0), pos, 7, 0)
pygame.display.flip()
frame += 1
angle += 10
pygame.quit()
exit()
相同的算法可用于 Sprite , 也。
在这种情况下,位置(
self.pos
)、枢轴( self.pivot
)和角度( self.angle
)是类的实例属性。在
update
方法self.rect
和 self.image
计算属性。最小示例: repl.it/@Rabbid76/PyGame-RotateSpriteAroundOffCenterPivot
import math
import pygame
class SpriteRotate(pygame.sprite.Sprite):
def __init__(self, imageName, origin, pivot):
super().__init__()
self.image = pygame.image.load(imageName)
self.original_image = self.image
self.rect = self.image.get_rect(topleft = (origin[0]-pivot[0], origin[1]-pivot[1]))
self.origin = origin
self.pivot = pivot
self.angle = 0
def update(self):
# offset from pivot to center
image_rect = self.original_image.get_rect(topleft = (self.origin[0] - self.pivot[0], self.origin[1]-self.pivot[1]))
offset_center_to_pivot = pygame.math.Vector2(self.origin) - image_rect.center
# roatated offset from pivot to center
rotated_offset = offset_center_to_pivot.rotate(-self.angle)
# roatetd image center
rotated_image_center = (self.pos[0] - rotated_offset.x, self.pos[1] - rotated_offset.y)
# get a rotated image
self.image = pygame.transform.rotate(self.original_image, self.angle)
self.rect = self.image.get_rect(center = rotated_image_center)
self.angle += 10
pygame.init()
size = (400,400)
screen = pygame.display.set_mode(size)
clock = pygame.time.Clock()
boomerang = SpriteRotate('Boomerang64.png', (200, 200), (48, 21))
all_sprites = pygame.sprite.Group(boomerang)
frame = 0
done = False
while not done:
clock.tick(60)
for event in pygame.event.get():
if event.type == pygame.QUIT:
done = True
pos = (200 + math.cos(frame * 0.05)*100, 200 + math.sin(frame * 0.05)*50)
boomerang.pos = pos
all_sprites.update()
screen.fill(0)
all_sprites.draw(screen)
#pygame.draw.line(screen, (0, 255, 0), (pos[0]-20, pos[1]), (pos[0]+20, pos[1]), 3)
#pygame.draw.line(screen, (0, 255, 0), (pos[0], pos[1]-20), (pos[0], pos[1]+20), 3)
#pygame.draw.circle(screen, (0, 255, 0), pos, 7, 0)
pygame.display.flip()
frame += 1
pygame.quit()
exit()
How do I rotate an image around its center using Pygame?
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关于python - 如何在 Pygame 中围绕偏离中心的支点旋转图像,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/59909942/