Ashton texture rendering interacts strangely with... well, everything.

ashton_test_1.rb

require 'gosu'
require 'ashton'

=begin
    This test is basic proof that rendering one texture interacts with rendering others.
    This will render a black screen, despite `secondary_buffer` never being drawn.
    If you alter the order of the `primary_buffer` and `secondary_buffer` renders in #update,
    then you will see the 250x250 red square render at 0,0 as expected.
=end

class TestGame < Gosu::Window
    def initialize
        super(500, 500, false)
    end

    def update
        primary_buffer.render do
            pixel.draw 0, 0, 0, 250, 250, 0xaaff0000 # RED
        end
        secondary_buffer.render do
            pixel.draw 250, 250, 0, 250, 250, 0xaa00ff00 # GREEN
        end
    end

    def draw
        primary_buffer.draw 0, 0, 0
    end
end

TestGame.new.show

ashton_test_2.rb

require 'gosu'
require 'ashton'

=begin
    All of that remains the same if we try to render onto another texture, and then render that.
    (Which isn't terribly surprising to me, but I don't know anything about OpenGL, so I'm not sure
    that it shouldn't be?)
=end

class TestGame < Gosu::Window
    def initialize
        super(500, 500, false)
        @screen = Ashton::WindowBuffer.new
    end

    def update
        primary_buffer.render do
            pixel.draw 0, 0, 0, 250, 250, 0xaaff0000 # RED
        end
        secondary_buffer.render do
            pixel.draw 250, 250, 0, 250, 250, 0xaa00ff00 # GREEN
        end
        @screen.render do
            primary_buffer.draw 0, 0, 0
        end
    end

    def draw
        @screen.draw 0, 0, 0
    end
end

TestGame.new.show

ashton_test_3.rb

require 'gosu'
require 'ashton'

=begin
    The crazy thing is that it actually seems like it's effecting things... retroactively?
    Even if we render `primary_buffer`, then **immediately** draw it to @screen,
    a subsequent render to `secondary_buffer`, which is never drawn, messes that up.

    In this example I have made `secondary_buffer` not render for 1 second at the beginning
    to show this effect more clearly.
=end

class TestGame < Gosu::Window
    def initialize
        super(500, 500, false)
        @screen = Ashton::WindowBuffer.new
    end

    def update
        primary_buffer.render do
            pixel.draw 0, 0, 0, 250, 250, 0xaaff0000 # RED
        end
        @screen.render do
            primary_buffer.draw 0, 0, 0
        end
        if Gosu::milliseconds > 1000
            secondary_buffer.render do
                pixel.draw 250, 250, 0, 250, 250, 0xaa00ff00 # GREEN
            end
        end
    end

    def draw
        @screen.draw 0, 0, 0
    end
end

TestGame.new.show

I am aware that I am not clearing the textures before rendering to them; that just introduces even more craziness.

Also, this is just the case with two textures. It gets even more incomprehensible when a larger number of textures and sprites are thrown into the mix.