Question

Is it possible (in terms of performance) to have a single multi-dimensional array that contains one 8-bit integer per pixel, for each pixel in the game window? I need to update the game window in a timely manner based on this array.

I’m aiming for something like the following:

import numpy
window_array = numpy.zeros((600, 600), dtype=numpy.int8)

#draw the screen
for (y, x), value in numpy.ndenumerate(window_array):
    if value == 1:
        rgb = (0, 0, 0)
    elif value == 2:
        rgb = (50, 50, 50)
    blit_pixel(x, y, rgb)

I’d like to be going 30-60 FPS, but so far my tests have yielded results that were much too slow to run at even a bad framerate. Is it possible to do, and if so, how?

Answer 1

I have never used pygame, so take my anwser with a grain of salt…

That said, it seems very unlikely that you are going to get any decent frame rate if you are iterating over 360,000 pixels with a python loop and doing a python function call at each one.

I learned from this other question (read the comment thread) that the pygame.surfarray module will give you a reference to the array holding the actual screen data. pygame.surfarray.pixels3d should return a reference to an array of shape (rows, cols, 3) where the last dimension holds the RGB values on screen. With that reference, you can change the pixels on screen directly, without needing a python loop doing something like:

import numpy
surf_array = pygame.surfarray.pixels3d(surface)
window_array = numpy.zeros(surf_array.shape[:2], dtype=numpy.int8)
...
surf_array[numpy.nonzero(window_array == 1)] = np.array([0, 0, 0])
surf_array[numpy.nonzero(window_array == 2)] = np.array([50, 50, 50])

Not sure if a call to pygame.display.update is needed to actually show your changes, but this approach will sustain a much, much higher frame rate than what you had in mind.