Table of Contents

OpenTK Samples

These samples show the main ways to host DrawnUI in an OpenTK application on Windows and Linux.

Use them as executable reference projects when you want to see how the OpenTK host is wired in a real app.

OpenTkPong

Path: src/OpenTk/Samples/OpenTkPong/

OpenTkPong is the clearest example of a fully drawn game window.

  • Uses DrawnUiWindow
  • Uses UpdateMode = Constant
  • Renders the whole game through DrawnUI instead of mixing a separate 3D scene underneath
  • Uses an AspectLayer so the playable area keeps the same proportions while the desktop window is resized

This is the sample to open first if you want to understand the simplest game-style DrawnUI host on OpenTK.

OpenTkGpuHost

Path: src/OpenTk/Samples/OpenTkGpuHost/

OpenTkGpuHost shows the event-driven desktop app path rather than the always-redrawing game path.

  • Uses DrawnUiWindow
  • Uses UpdateMode = Dynamic
  • Sleeps between frames and wakes only when the canvas becomes dirty
  • Demonstrates the lower-power, UI-application style of hosting DrawnUI in OpenTK

This is the best sample for editors, tools, launchers, and other desktop UI surfaces that do not need constant frame updates.

OpenTkOverlay

Path: src/OpenTk/Samples/OpenTkOverlay/

OpenTkOverlay demonstrates the mixed-host case: raw OpenGL scene first, DrawnUI overlay second.

  • Uses CanvasHost instead of DrawnUiWindow as the primary app base
  • Renders a rotating 3D cube and lit environment with raw OpenGL
  • Composites a semi-transparent DrawnUI control panel on top of the existing framebuffer
  • Demonstrates the required GL-state restore block before raw GL drawing and ResetGrContext() before DrawnUI rendering

The overlay panel is useful because it shows several real integration points at once:

  • SkiaBackdrop and GlassBackdropEffect for a live glass-like panel over 3D content
  • labels updated from the render loop while staying friendly to layout performance
  • SkiaEditor input and keyboard routing inside the overlay
  • gesture and focus routing in a layered host
  • AcceleratedRetained canvas mode to preserve the underlying GL framebuffer

This is the sample to study when you already have an OpenGL scene and want DrawnUI as a HUD, overlay, tools panel, or in-game desktop UI.

Which Sample To Start With

Choose the sample that matches your host model:

  • Start with OpenTkPong if you want a fully drawn app or game
  • Start with OpenTkGpuHost if you want a desktop UI app with event-driven rendering
  • Start with OpenTkOverlay if you already own the OpenGL render loop and want DrawnUI on top
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