Just spent a while debugging something before I was finally able to figure out the issue.
Apparently the image that is generated by Window#record is not a "true" gosu image?
e.g.
img1 = Gosu::Image.new("some_file.gif")
img2 = window.record(100, 100) { img1.draw(0, 0, 0) }
window.record(100, 100) do
img1.draw(0,0,0) #=> is fine and works like a charm
img2.draw(0,0,0) #=> generates an exception: "Custom code cannot be recorded into a macro (RuntimeError)"
end
Is there a reason for this or is this a bug?
By jlnr (dev)
Date 2012-11-26 08:38
The result of record() is not a "true" Gosu::Image in that it is not rendering to a texture; it is recording the contents of a block to a vertex array.
What you are seeing is not a bug, it is a missing feature. Internally, the Image returned by record uses a custom OpenGL block to render itself, which is what the error message is trying to say. Since Gosu cannot know what a custom GL block is doing, it cannot capture the output into a vertex array (though it could capture it to a texture - if that is what record were doing :) ).
I have two To-Do items that would help you, one is to implement render-to-texture. The other is to simply expand the inner vertex array into the outer array for the special case where a vertex array is drawn inside a record block.
They're super-low-priority compared to everything else now, but I enjoy hacking on the record code a lot, so maybe I can sneak it into a break some time.
