Graphics.snap_to_bitmap doesn't work

[NuriYuri]

Test: Graphics.snap_to_bitmap.to_png_file('test.png') gives a transparent png. This is not the expected behaviour.

[NuriYuri]

I found the issue, for whatever reason the texture is transparent.
After running the snap to bitmap line you can run this:

@i = Image.new('test.png')
640.times do |x| 480.times do |y| @i.set_pixel(x, y, @i.get_pixel(x, y).set(nil, nil, nil, 255)) end end
@i.to_png_file('test2.png')

You will see the content.