This is an attempt to make GWEN a more opengl aware ui. The expectation is to build it to provide better performance with the way modern opengl works (and later vulkan)
The OpenGLCore demo on the OpenGL 3.0+ core renderer with the textured skin's Tokyo Night theme.
- Rendering-API agnostic. UI logic — layout, padding, docking, hover/highlight/focus,
hit-testing — is decoupled from drawing. A backend just implements one interface
(
gweni::renderer::Base), so the same UI runs on OpenGL today and Vulkan (or others) later. - Two-phase frame.
canvas->updateCanvas()does the layout/display logic and records what changed;canvas->renderCanvas()issues only the draw-state changes needed. - Cost scales with change, not size. Each control owns persistent renderer primitive ids that index into a large GPU buffer (VBO). Only primitives that changed are updated, and the intent is to upload just those regions to the GPU (or a larger contiguous span when that copy is faster), then render straight from the buffer. A simple backend may instead just redraw every control each frame.
See docs/architecture.md for the full design and the current implemented-vs-planned status, and docs/layout.md for the layout system.
| Button | RadioButton |
| TabControl | TreeControl |
| Properties | PageControl |
| ListBox | Slider |
| Text (OpenSans 8-16 px) | ProgressBar |
| ComboBox | Separator (with a caption, vertical, and bullets) |
| Selectable (toggle rows and a single-selection group) | Context menu (setContextMenu, opened with a right-click) |
Each control is shown on its own in ControlTest. All of these images are rendered offscreen by
tools/capture_samples.sh (see AGENTS.md).
The examples are built in the build container (./run_docker.sh ./generate.sh linux, then
./run_docker.sh cmake --build build_linux_x64_debug -j; see AGENTS.md → "Building"), and
the interactive ones run on the Linux host, where there is a display. ./run.sh runs them from
any directory:
./run.sh # OpenGLCore, the interactive demo (debug build)
./run.sh -b # build first (through run_docker.sh), then run
./run.sh controltest --control ButtonDemo # ControlTest, one control on its own
./run.sh release controltest --list # the release tree; asan picks the ASAN tree
./run.sh -h # usage; ./run.sh controltest --help is ControlTest's./run.sh [-b] [debug|release] [asan] [opengl|controltest] [args...] passes every argument
after its own words to the exe unchanged, and runs it in your current directory, so relative
paths (--shot, --screenshot, --resources) are relative to where you are. Without -b it
never builds; if the build tree or the exe is missing it says which and how to make it.
Inside the container there is no display, so only the headless modes work there:
./run.sh controltest --headless --shot /tmp/x.png./run.sh is a convenience only. The exes run directly from any directory too
(build_linux_x64_debug/examples/openglcore/{OpenGLCore,ControlTest}): by default they load the
resources/ that the build copies next to them. --resources <dir> loads everything from
<dir> instead, e.g. --resources resources from the repo root to pick up live
DefaultSkin.json edits without a rebuild.
To run on the host, the container-built exes need:
- glibc 2.34 or newer, and the libstdc++ of GCC 11 or newer (
GLIBCXX_3.4.29); - a glvnd GL driver, which provides
libGLX.so.0,libOpenGL.so.0andlibEGL.so.1.
Ubuntu 22.04+, Debian 12+ and Fedora 35+ all qualify. The vcpkg dependencies are linked statically, so nothing else is needed. The image is built with your UID/GID, so the build output is owned by you.
GWEN was originaly created by Garry Newman, and released under MIT License. https://github.com/garrynewman/GWEN