How to change pixel_ratio in pyglet?

Question

I coded a game using pylet. It uses a static window with width 1600 and height 900 assuming users have a fullHD display so everything will be visible. However on some devices (with small displays) the window is way bigger as expected. I figured out that the pixel_ratio is set up (for example to 2.0) making each virtual pixel to be displayed double size (2x2) in physical pixel.

I want to prevent this behavior but can't figure out how, I know I can get the pixel ratio easily by get_pixel_ratio() but I actually don't know how to set them or prevent pyglet from automatically setting them.

I also tried to use glViewport which seemed to have an effect but it didn't worked the way I wanted.

So how can I change the pixel_ratio or prevent changing it automatically.

Answer 1

Asked around in the official discord server for information, as I tried to reproduce the issue myself with some code, and this is what I used to test it:

import math
from pyglet import *
from pyglet.gl import *

key = pyglet.window.key

class main(pyglet.window.Window):
    def __init__ (self, width=800, height=600, fps=False, *args, **kwargs):
        super(main, self).__init__(width, height, *args, **kwargs)
        self.x, self.y = 0, 0

        self.keys = {}

        verts = []
        for i in range(30):
            angle = math.radians(float(i)/30 * 360.0)
            x = 100*math.cos(angle) + 300
            y = 100*math.sin(angle) + 200
            verts += [x,y]

        self.pixel_ratio = 100
        self.circle = pyglet.graphics.vertex_list(30, ('v2f', verts))

        self.alive = 1

    def on_draw(self):
        self.render()

    def on_close(self):
        self.alive = 0

    def on_key_release(self, symbol, modifiers):
        try:
            del self.keys[symbol]
        except:
            pass

    def on_key_press(self, symbol, modifiers):
        if symbol == key.ESCAPE: # [ESC]
            self.alive = 0

        self.keys[symbol] = True

    def render(self):
        self.clear()

        glClear(pyglet.gl.GL_COLOR_BUFFER_BIT)
        glColor3f(1,1,0)
        self.circle.draw(GL_LINE_LOOP)

        self.flip()

    def run(self):
        while self.alive == 1:
            self.render()

            # -----------> This is key <----------
            # This is what replaces pyglet.app.run()
            # but is required for the GUI to not freeze
            #
            event = self.dispatch_events()

if __name__ == '__main__':
    x = main()
    x.run()

Not that the code mattered heh, since the variable pixel_ratio is just, and I quote: "indicating that the actual number of pixels in the window is larger than the size of the Window created."

This is something OSX does to cope with the high DPI, using this information you should be able to scale your graphics accordingly. Window.get_framebuffer_size() will show you the difference in requested Window size and Framebuffer size, if any.

So your only way to actually scale up, would be to use glScale or if you're using sprites you can use Sprite.scale to scale the image-data. If you're using 2D graphics I'd go with the sprite option as it's pretty easy to work with.