Overlays

Game overlays are usually created in one of two ways:

• by injecting code into the game and hooking rendering API functions (OpenGL, Direct3D, Vulkan, etc.)
• by creating a specially crafted window

This crate uses the second technique, and I'm working on a yet-to-be-announced crate utilizing the first technique.

There is also (potentially) a third way to draw an overlay which involves messing with the compositor, but I haven't really looked into that.

Usage

use overlay::OverlayBuilder;
use winit::event_loop::EventLoop;

fn main() {
    let event_loop = EventLoop::new();
    let mut overlay = OverlayBuilder::new().build();

    // Initialize renderer

    event_loop.run(..);
}

To toggle the overlay, use Overlay::toggle(..).

Limitiations

• The game has to be in either Windowed or Windowed Borderless.
• Currently only works on Windows and X11.
• There's currenty no way to specify which monitor the overlay spawns on.
• "Hugging" the target window isn't implemented yet (#2).
• (Windows) The window that the overlay is based on will show as an icon in the task bar.
• (Windows) The window that the overlay is based on behaves like a window in other inconvenient ways.

How does it work?

The Windows implementation is based on this CodeProject article from 2007.