Rotating a rectangle (not image) in pygame

问题

In pygame I use pygame.draw.rect(screen, color, rectangle) for all the rectangles in my program. I want to be able to rotate these rectangles to any angle. I have seen the following code to rotate IMAGES but my question is with RECTANGLES.

pygame.transform.rotate(image, angle)

But I am working with rectangles, I don't have an image or "surface" that I can rotate. When I try to rotate a rectangle with

rect = pygame.draw.rect(screen, self.color, self.get_rectang())
rotatedRect = pygame.transform.rotate(rect, self.rotation)
screen.blit(rotatedRect)

This gives TypeError: must be pygame.Surface, not pygame.Rect on the line with .rotate()

My question is, how can I rotate a and display a RECTANGLE(x,y,w,h), not an image, in pygame.

The linked post that this is a "potential duplicate" of is not a duplicate. One answer explains about the consequences of rotating a rectangle and the other uses code for rotating an image.

回答1:

See the second answer here: Rotating a point about another point (2D)

I think rectangles can only be horiz or vertical in their oreintation. You need to define the corners and rotate them and then draw and fill between them.

The other way is to make a class

class myRect(pygame.Surface):
    def __init__(self, parent, xpos, ypos, width, height):
      super(myRect, self).__init__(width, height)
      self.xpos = xpos
      self.ypos = ypos
      self.parent = parent

    def update(self, parent):
      parent.blit(self, (self.xpos, self.ypos))

    def rotate(self, angle):
      #(your rotation code goes here)

and use that instead, as then you will be able to rotate it using the transform function.

回答2:

import pygame as py  

# define constants  
WIDTH = 500  
HEIGHT = 500  
FPS = 30  

# define colors  
BLACK = (0 , 0 , 0)  
GREEN = (0 , 255 , 0)  

# initialize pygame and create screen  
py.init()  
screen = py.display.set_mode((WIDTH , HEIGHT))  
# for setting FPS  
clock = py.time.Clock()  

rot = 0  
rot_speed = 2  

# define a surface (RECTANGLE)  
image_orig = py.Surface((100 , 100))  
# for making transparent background while rotating an image  
image_orig.set_colorkey(BLACK)  
# fill the rectangle / surface with green color  
image_orig.fill(GREEN)  
# creating a copy of orignal image for smooth rotation  
image = image_orig.copy()  
image.set_colorkey(BLACK)  
# define rect for placing the rectangle at the desired position  
rect = image.get_rect()  
rect.center = (WIDTH // 2 , HEIGHT // 2)  
# keep rotating the rectangle until running is set to False  
running = True  
while running:  
    # set FPS  
    clock.tick(FPS)  
    # clear the screen every time before drawing new objects  
    screen.fill(BLACK)  
    # check for the exit  
    for event in py.event.get():  
        if event.type == py.QUIT:  
            running = False  

    # making a copy of the old center of the rectangle  
    old_center = rect.center  
    # defining angle of the rotation  
    rot = (rot + rot_speed) % 360  
    # rotating the orignal image  
    new_image = py.transform.rotate(image_orig , rot)  
    rect = new_image.get_rect()  
    # set the rotated rectangle to the old center  
    rect.center = old_center  
    # drawing the rotated rectangle to the screen  
    screen.blit(new_image , rect)  
    # flipping the display after drawing everything  
    py.display.flip()  

py.quit()

来源：https://stackoverflow.com/questions/36510795/rotating-a-rectangle-not-image-in-pygame

标签

python

rotation

pygame

rectangles