ImPlot

At every frame, the GUI function draws the plot with ImPlot and the knobs with imgui-knobs, and reads their values right there. No callbacks, no widget objects: that is the immediate mode.

Both are add-ons, activated in one call: immapp.run(gui, with_implot=True, with_markdown=True). A good start for a small app.

A markdown editor with a live preview, and a pie chart whose values you can drag. Tick More info under each part to see how it is done. The add-ons are activated with immapp.AddOnsParams.

A few lines of Python: a parametric curve, scaled by a pulse at each frame. Turn the knobs to change the heart rate, or its thickness.

Then read how it works, formula by formula, next to its numpy code.

The dashboard shows what a vibration analyst would watch:

It is the equation of simple harmonic motion (for the pendulum, at small angles). Adjust the mass and the spring stiffness, and watch how the motion changes.

Drag the angles to set initial positions, then release and watch chaos unfold.

Adjust the number of circles to see how the approximation improves.

Each bird stays apart from its neighbors (separation), flies their way (alignment), and stays with them (cohesion). This is the boids model of Craig Reynolds (1986).

The logistic map, x(n+1) = r * x(n) * (1 - x(n)), models for example the growth of a population with limited resources. Depending on r, it is stable, periodic (in 2-cycles, 4-cycles, etc), or chaotic. Let’s explore this.

Press Play and two centuries go by. Click a bubble to pin it and draw its path through time; pick other indicators for the axes.

Choose a window preset or drag its bounds on the histogram. Click a structure: the region grows across the slices, and the app measures it and shows it in 3D. A second tab finds the blood vessels of a retina. For research and teaching, not for diagnosis.

The left sky shows the galaxy as it is, the right one what we see through the lens. Drag the galaxy (yellow) and the lens (blue), turn the knobs, or start from a preset: an Einstein ring, two images, a giant arc, the Einstein Cross. The thin lines are the critical curve, where the magnification diverges, and its map in the source plane, the caustic: as the galaxy crosses it, images are born or merge. Hover a pixel of the observed sky to see where its light comes from.

Content that changes on its own says so with hello_imgui.set_item_is_live(), and keeps the full speed while it is visible. The idling settings are global.

Each section shows its source, ready to copy. The page is a document: a table of contents, a search, headings that fold, and widgets between its renders (a live plot).

Several renders and a section of widgets (a plot) share them, in one scroll area. The search also finds the text of the code blocks and of the collapsed sections. The headings fold.

Change a parameter, and the nodes downstream follow at once. The patterns of imgui-node-editor for a real app: typed pins, links refused with a reason, a node created by dropping a link in empty space, menus, a group.

Lines, scatter, bars, heatmaps, histograms, real-time plots and more, in Python and C++. From Dear ImGui Explorer, the interactive manual for Dear ImGui and its libraries.

The same exists for child windows, menus, popups, tables, tabs, fonts and styles, and for ImPlot with implot_ctx. Open a section to try it and read its code. See the Python tips.

In async mode (immapp.nb.start()), another cell keeps computing, as fast as it can, between the frames: stream data into a plot, or train a model and tune it while it learns. The page explains both modes; its video trains a neural network live, its learning rate on a slider.

On a mobile or a tablet, Hello ImGui turns a finger into what its user expects: a swipe scrolls, a tap clicks, a held finger opens a context menu, a pinch scales the app (its font) or zooms a plot or an image, two fingers pan, and a keyboard button appears next to a text field.