How do you rotate an image in Pygame without constantly redrawing the background?-CodePudding

I am making a randomized spinner in pygame, but the only method I've found is to constantly redraw the whole screen. Is there a way that doesn't use this, it becomes extremely laggy.

CodePudding user response：

You can not. why do you want that? It is common to redraw the entire scene in each frame. Of course you can try to redraw just a rectangular section of the background. However, this is usually not worth the effort.

The pygame way to do this is to pass a list of rectangular areas to pygame.display.update(). If rectangles are passed to pygame.display.update() then not the entire display will be redrawn, just the specified areas::

Update portions of the screen for software displays
[...] You can pass the function a single rectangle, or a sequence of rectangles. It is more efficient to pass many rectangles at once than to call update multiple times with single or a partial list of rectangles.

e.g.:

while run:
    # [...]

    screen.blit(background, (0, 0))    

    screen.blit(image1, bounding_rect1)
    screen.blit(image2, bounding_rect2)
  
    pygame.display.update([bounding_rect1, bounding_rect2])

CodePudding user response：

That is how computer animation works, you're redrawing the screen on every frame. Every game practically works the same way. I am not sure what graphics pipeline pygame uses but in OpenGL you usually initialize all your geometry outside of the render loop and then use pointers to batch-process everything in the render-loop so you're not duplicating a lot of boilerplate code or making duplicate objects every frame.