Installation & First Run

Two minutes from download to your first live particle effect.

1. Get the editor

Download LempoParticleEditor.exe from the Releases page (or from itch.io) and run it — no Python installation required.

Requirement	Value
OS	Windows 10/11 (64-bit)
GPU	Any GPU with OpenGL 3.3 support
Editor version	`v0.2.0` (shown in the window title)
Pairs with	Extension `v0.2.0` · export format `v1.2` (v1.0 and v1.1 files migrate automatically)

2. Choose your editor mode

The first thing you see is the startup dialog — the app logo plus four mode cards. Each mode pairs a renderer (2D sprites / 3D meshes) with a simulation style (classic particles / trails & ribbons):

Startup dialog — pick your editor mode (press 2 / 3 / 4 / 5) — **Startup dialog** — pick your editor mode (press 2 / 3 / 4 / 5)

Key	Mode	Best for
`2`	2D \| Sprites & SVG	2D games: point sprites, SVG shapes, images
`3`	3D \| Meshes & Billboards	3D scenes: spheres, cubes, custom GLB models, billboards
`4`	2D \| Trails & Ribbons	Sword slashes, speed lines, magic beams in 2D
`5`	3D \| Trails & Ribbons	Arrows, projectiles, ribbons in 3D

You can switch between the 2D and 3D dot modes any time from the top toolbar (2D / 3D toggle). Trails mode is a dedicated mode chosen at startup — see Trails & Ribbons.

3. Play with a template

Load a template

The editor starts on the Default effect. Use the template list in the sidebar (Explosion, Fire, Rain, Snow — 2D + 3D variants) to load a finished effect.

Watch it live

The Dear PyGui main viewport renders through its drawlist, with an optional OpenGL raster layer for dense scenes. Use Browser Fast Preview for the separate Three.js/PixiJS preview window; it syncs edits every 500 ms.

Tweak the numbers

Flow, lifetime, colors, gravity, blend mode… every change shows up immediately. Ctrl+Z undoes — 100 steps deep.

Export

Hit Export JSON (or Save) and you get an .json effect file validated against the export schema — ready for the GDevelop extension.

Run from source / rebuild

pip install dearpygui
python editor/studio_imgui.py        # Dear PyGui UI (full features)

Tk fallback (shared logic layer — no blend/seed/force-field widgets, but those values are preserved on round-trip):

python editor/particle_studio.py

Rebuild the packaged app (compile check → C++ core build if stale → PyInstaller → smoke test → Windows shortcut):

python tools/rebuild_app.py

This produces dist/LempoParticleEditor.exe plus the Lempo Particle Editor desktop shortcut (both carry the Lempo icon).

Binaries (dist/, *.exe, *.pyd, node_modules/) are never committed — they are rebuilt locally and shipped through GitHub Releases.