问题描述
import sys,pygame
from math import sin,cos,radians,pi
from pygame.locals import QUIT,MOUSEBUTTONDOWN
pygame.init()
SURFACE = pygame.display.set_mode((780,920))
FPSCLOCK = pygame.time.Clock()
def Line():
speed = 0
while True:
for event in pygame.event.get():
if event.type == QUIT:
pygame.quit()
sys.exit()
if pygame.mouse.get_pressed() [0]:
speed += 26
if speed > 60:
speed = 60
else:
speed -= 15
if speed < 0:
speed = 0
SURFACE.fill((255,0))
radius = speed * 0.8
pygame.draw.line(SURFACE,(5,80,255),(295,127),(sin(200-radius),cos(300-radius)),8)
pygame.display.update()
FPSCLOCK.tick(6)
if __name__ == '__main__' :
Line()
我正在尝试编写一条绕中心轴逆时针旋转的线段。很难理解。终端位置部分对我来说很难。
解决方法
我建议使用pygame.math.Vector2
。
定义中心点,半径,直线的方向向量和角度
center_x,center_y = SURFACE.get_rect().center
radius = 100
line_vector = pygame.math.Vector2(1,0)
angle = 0
由于要逆时针旋转,因此需要在按下鼠标按钮时减小角度:
if pygame.mouse.get_pressed()[0]:
angle -= 1
使用pygame.math.Vector2.rotate()
旋转方向矢量并计算直线的旋转起点和终点
rot_vector = line_vector.rotate(angle) * radius
start = round(center_x + rot_vector.x),round(center_y + rot_vector.y)
end = round(center_x - rot_vector.x),round(center_y - rot_vector.y)
使用start
和end
画线:
pygame.draw.line(SURFACE,(5,80,255),start,end,8)
最小示例: repl.it/@Rabbid76/PyGame-VectorRotateLine
完整示例:
import sys,pygame
from math import sin,cos,radians,pi
from pygame.locals import QUIT,MOUSEBUTTONDOWN
pygame.init()
SURFACE = pygame.display.set_mode((780,920))
FPSCLOCK = pygame.time.Clock()
def Line():
center_x,center_y = SURFACE.get_rect().center
radius = 100
line_vector = pygame.math.Vector2(1,0)
angle = 0
while True:
for event in pygame.event.get():
if event.type == QUIT:
pygame.quit()
sys.exit()
if pygame.mouse.get_pressed()[0]:
angle -= 1
print(angle)
rot_vector = line_vector.rotate(angle) * radius
start = round(center_x + rot_vector.x),round(center_y + rot_vector.y)
end = round(center_x - rot_vector.x),round(center_y - rot_vector.y)
SURFACE.fill((255,0))
pygame.draw.line(SURFACE,8)
pygame.display.update()
FPSCLOCK.tick(60)
if __name__ == '__main__' :
Line()
如果要绕线的起点旋转,则不需要中心点。定义行的开头:
start_x,start_y = SURFACE.get_rect().center
length = 200
计算旋转的终点:
rot_vector = line_vector.rotate(angle) * length
start = start_x,start_y
end = round(start_x + rot_vector.x),round(start_y + rot_vector.y)