Rotating a sprite using pygame

[Alex_29]

Hi, I've just started using Python/Pygame as a hobby.

I've gotten the code to draw my Plane.png and move it using the wsad keys, and I mapped the q and e keys to rotate it which it does, but each time it rotates, it 'falls' down the screen to the bottom right and after a few key presses, disappears.
I read that this is because when it turns the sprite, it adds padding to resize the image while it is turning. I think that each time it turns, it adds more padding, making it add exponentially for each keypress. I can't figure out how to stop this from happening. Any help for a beginner greatly appreciated!

The Colours import is just a file where I keep my pre-defined colours for easier colour filling, and Plane.gif is an inch by inch and a half gif of a black plane with transparent background, and loads no problem, it just flies away when i use the e or q keys.

import pygame, sys, time, random
from pygame.locals import *
from Colours import *
from PIL import Image, ImageDraw




class MySprite(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.image.load('Plane.gif').convert()
        self.rect = self.image.get_rect()
        self.x = 0
        self.y = 0

    def draw(self,surface):

            surface.blit(self.image,(self.x,self.y))


    def onKeyPress(self):

        key = pygame.key.get_pressed()
        distance = 5
        if key[ord('s')] or key[pygame.K_DOWN]: #down
            self.y += distance
        elif key[ord('w')] or key[pygame.K_UP]: #up
            self.y -= distance
        if key[ord('d')] or key[pygame.K_RIGHT]: #right
            self.x += distance
        elif key[ord('a')] or key[pygame.K_LEFT]: #left
            self.x -= distance

        rotate = pygame.transform.rotate
        if key[ord('e')]:
            self.image = rotate(self.image, 10)
        elif key[ord('q')]:
            self.image = rotate(self.image, -10)

class Event(object):

    def __init__(self):

        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                pygame.quit()
                sys.exit()
            elif event.type == pygame.KEYDOWN:
                if event.key == pygame.K_ESCAPE:
                    pygame.quit()
                    sys.exit()


pygame.init()

fps = 30
fpsClock = pygame.time.Clock()

size = width,height = 800,600
screen = pygame.display.set_mode(size)
mySprite = MySprite()

while True:

    event = Event()
    screen.fill(Blue)

    mySprite.draw(screen)
    mySprite.onKeyPress()

    pygame.display.update()

    fpsClock.tick(fps)

There's the code, hope you can help, thanks!

[sneekula]

Check:
http://forums.devshed.com/python-programming-11/rotating-sprite-pygame-965435.html

[sneekula]

Did you look at
http://cs.iupui.edu/~aharris/pygame/ch08/
under
rotate.py and drawBounds.py

[juanpa_2510]

You have to use an auxiliar image variable, so you rotate the image and saves it in the aux var, and the original image is not modified.

self.image = pygame.image.load('Plane.gif').convert()
self.rotatedImage = rotate(self.image, 10)
surface.blit(self.rotatedImage,(self.x,self.y))

try it and tell us how it worked.
Maybe you will see some strange rotation behavior and it depends on how you managed the center of the image or rect.

[sneekula]

Maybe it's similar to the strange effects I encountered here:

# exploring module pygame
# draw a white ellipse on a black screen and move it
# note: rect behaves strange, stretches the ellipse!!!

import pygame as pg

black = (0, 0, 0)

# window/screen width and height
w = 600
h = 500
# default background is black
screen = pg.display.set_mode((w, h))

# set up some of the ellipse specs
# (r, g, b) tuple --> white
color = (255, 255, 255)
# optional width of the ellipse's border
# if width = 0 (or not given) the shape is filled with color
width = 0

for delta in range(0, 180, 3):
    # (x1, y1, x2, y2) upper left and lower right corner
    # coordinates of the rectangle the ellipse is bound by
    # if the recangle forms a square then a circle is drawn
    x1 = 30+delta
    y1 = 20
    x2 = 130+delta
    y2 = 120
    rect = (x1, y1, x2, y2)
    print(x1, y1, x2, y2)  # test seems okay
    # this erases the old sreen with black
    screen.fill(black)
    pg.draw.ellipse(screen, color, rect, width)
    # update screen
    pg.display.flip()
    milliseconds = 50
    pg.time.delay(milliseconds)

# event loop ...
running = True
while running:
    for event in pg.event.get():
        # quit when window corner x is clicked
        if event.type == pg.QUIT:
            running = False

[juanpa_2510]

It doesn't change if you have delta only for x1, but rect position turns weird.

I forgot to say in my previous post that you have to obtain the rect from each rotated image and set
self.rect.center = [self.x, self.y] on each step.
Well, try it, maybe I'm doing something unnecessary.