Getting rotated rect of rotated image in Pygame

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I have a problem about pygame rect.

The rect isn't like what I want.

I saw I can do this with sprite class. But I don't want use sprites. I didn't understand differences of Sprite Rect and Image Rect.

I want to get rect like this

But I am getting like this

Here is my rect function:

def getRect(self):
    return self.image.get_rect(center=(self.x,self.y))

Image is rotationed image.

I haven't very well english, I've told you as much as I can.

pygame-surface pygame python
1 Answers

get_rect() returns a pygame.Rect object. A pygame.Rect stores a position and a size. It is always axis aligned and cannot represent a rotated rectangle.

Use pygame.math.Vector2.rotate() to compute the corner points of the rotated rectangle. orig_image is the image before it is roatated:

rect = orig_image.get_rect(center = (self.x, self.y))

pivot = pygame_math.Vector2(self.x, self.y)

p0 = (pygame.math.Vector2(rect.topleft) - pivot).rotate(-angle) + pivot 
p1 = (pygame.math.Vector2(rect.topright) - pivot).rotate(-angle) + pivot 
p2 = (pygame.math.Vector2(rect.bottomright) - pivot).rotate(-angle) + pivot 
p3 = (pygame.math.Vector2(rect.bottomleft) - pivot).rotate(-angle) + pivot

Use pygame.draw.lines() to draw the rotated rectangle:

pygame.draw.lines(screen, (255, 255, 0), True, [p0, p1, p2, p3], 3)

See also How do I rotate an image around its center using PyGame? and How can you rotate an image around an off center pivot in PyGame.

Minimal example: repl.it/@Rabbid76/PyGame-RotatedRectangle

import pygame

pygame.init()
window = pygame.display.set_mode((400, 400))
font = pygame.font.SysFont(None, 50)
clock = pygame.time.Clock()

orig_image = font.render("rotated rectangle", True, (255, 0, 0))
angle = 30
rotated_image = pygame.transform.rotate(orig_image, angle)

def draw_rect_angle(surf, rect, pivot, angle):
    pts = [rect.topleft, rect.topright, rect.bottomright, rect.bottomleft]
    pts = [(pygame.math.Vector2(p) - pivot).rotate(-angle) + pivot for p in pts]
    pygame.draw.lines(surf, (255, 255, 0), True, pts, 3)

run = True
while run:
    clock.tick(60)
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False    

    window.fill(0)
    window_center = window.get_rect().center
    window.blit(rotated_image, rotated_image.get_rect(center = window_center))
    rect = orig_image.get_rect(center = window_center)
    draw_rect_angle(window, rect, window_center, angle)
    pygame.display.flip()

pygame.quit()
exit()
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