A free, open-source ProBuilder / UniBuilder-style mesh building plugin for Godot 4 — primitives, drag-to-create, and direct vertex/edge/face editing inside the editor, auto UVs in the spirit of Unity's ProBuilder. One click export to baked glb or custom pbm format optimized for retro pipelines, tested on a real Sony PSP.

Pure GDScript: PoiBuilder is written 100% in standard GDScript. It runs in the standard Godot 4 editor (no Godot Mono / .NET build required) and needs no C/C++ compilation, no GDExtension, and no native binaries — just drop the addons/poibuilder/ folder into any standard Godot 4 project and enable it.

This is an AI-assisted hobby project. PoiBuilder was written mainly for my own use, because I wanted a free and open source UniBuilder equivalent for Godot. It is developed with the help of AI coding agents, and while it is very usable, I make no guarantees about support, maintenance, or polish. The code is all here — use it, improve on it, or reference it to build your own.

If you want an actually maintained and polished product that achieves the same thing, keep an eye on UniBuilder (upcoming): https://calinleafshade.itch.io/unibuilder

Another open source Godot level builder in a similar spirit is GoBuild: https://github.com/marcel-b-roodt/GoBuild

The bridge between modern level authoring and retro hardware is the PoiRetro .pbm v3 map format — one click bakes a playable map for fixed-function targets (PSP, Dreamcast, PS2, custom engines); v1/v2 files still load.

In the file format and the addon (any engine can consume these):

• Bake everything offline: direct/point/spot lighting, ray-traced shadows and multi-sample ambient occlusion baked into vertex colors; unique painted textures baked into power-of-two 4x4 tile atlases (unpainted tiles share base textures); grid-aligned quad subdivision turns stairs and doorways into clean quads with zero sliver fans.
• Collision hulls (box, trimesh, ramp) extracted automatically for player traversal and raycasting.
• Animated UV scrolling: speed authored on the material, live in the editor viewport, carried through GLB, replayed identically by any consumer.
• Stateless particle emitters (standard emitters lump): authored as ordinary GPUParticles3D; particle i at time t is a closed form of (t, i, seed) — a runtime costs a few flops per particle, no simulation, one draw call per emitter. Additive emitters need no sorting; blended ones are drawn back-to-front.
• Arbitrary binary metadata lumps: level descriptors, waypoints, spawn points, triggers, walkable nav meshes.
• Three-valued alpha modes (opaque / cutout / blend) per texture, so foliage silhouettes and waterfall sheets survive the bake.
• Modern target too: the same scene exports to standard .glb with native PBR materials for Godot 4, Unreal, Unity, or WebGL.

In the bundled PSP demo engine (retro_engine/psp, plain C, measured on real hardware — a reference consumer of the format, not a requirement):

• Zero-CPU rendering: 24-byte interleaved vertices matching Sony GU registers, 16-byte aligned for direct display-list DMA; 16-bit swizzled RGBA5551 textures halve VRAM bandwidth.
• Load-time mip chains (alpha-preserving for cutouts) with a measured single-level LOD policy: the worst showcase view went 25.2 ms → 2.79 ms per frame, the whole camera sweep runs at 2.4–5.0 ms/frame (200–450 fps). Known limitation: a grazing-angle LOD step between tile quads (per-primitive LOD, no anisotropic filtering); painted meshes pin to one mip level by default to remove it.
• Pre-baked vertex lighting with zero runtime light cost, native collision, stateless emitters at 0.72 ms GPU / 1.14 ms CPU for a 256-particle budget, and a 60 FPS fly/walk player with HUD.
• Measured, not assumed: every perf claim comes from ./run_psp_hw.sh on a real PSP over USB. PPSSPP cannot price a frame (it rasterises on the host GPU) and is used for correctness only. See retro_engine/psp/OPTIMIZATION.md (engine inventory), retro_engine/psp/HARDWARE-TESTING.md (measurement), and SPEC_RETRO_FORMAT.md §11 (how to write your own consumer).

Building & mesh editing

• 14 primitives (cube, stairs, curved stairs, prism, cylinder, plane, door, pipe, cone, sprite, arch, sphere, torus, n-gon) with drag-to-create on any surface or the grid: drag the base, move to set height, click to confirm; parameter modals with live preview and re-editable pristine shapes.
• Object / vertex / edge / face selection modes with hover + selection highlights, rubber-band multi-select, occlusion-aware picking, and mode-switch selection conversion (ProBuilder parity).
• Move/rotate/scale through the editor's native gizmos at the element pivot (Element / Object / World spaces), center scale handle, Shift+Move extrude, Shift+Scale inset.
• Mesh ops: extrude, inset, bevel (multi-segment), loop cut, subdivide, merge, weld, bridge, connect, collapse, fill hole, knife, delete, detach — all with live previews and full undo.
• Advanced selection: all / invert / grow / shrink, coplanar, similar, boundary, face loop & ring.
• Architectural trim: one-drag trim strips in six profiles, plus a Trim Walls tool that sweeps mitred trim along clicked wall faces (floor/ceiling-aware, doorway jambs break the run).
• Object tools: merge, mirror, center pivot, freeze transform, Poibuilderize (convert MeshInstance3D or CSG into an editable mesh), CSG booleans (union / subtract / intersect), smoothing groups & auto-smooth.
• Precision: toggleable grid snap, hold-V vertex snap, proportional (soft) editing with adjustable radius.

Materials, UVs & dressing

• Auto-UV projection: uniform 1 m repeat heuristic, textures never stretch on resize, persistent anchor keeps seams aligned, 45° diagonal tiling.
• Material & UV dock: palette, per-face assignment, drag-and-drop from the FileSystem, tiling/offset/angle controls, face tint.
• Texture selection mode: the same move/rotate/scale gizmo manipulates the selected faces' UVs directly in the 3D view — slide a texture, spin a floor, scale a repeat without opening any panel.
• Multi-layer texture splatting (8 blend layers per face) and decal stamping with live preview, wheel-rotate and ctrl-wheel scale.
• Billboard sprite placement: always-armed sprite tab — pick a texture, click a surface, raise, scale; texture carousel on drag.
• Click-to-place stateless particle emitters: authored as ordinary GPUParticles3D, but particle i at time t is a closed form of (t, i, seed) — no simulation to tick, one draw call per emitter, and the export carries the authoring as data so any consumer replays the exact same fire, smoke or mist (see the retro pipeline above and the docs for details).
• Dedicated 2D UV editor: pan/zoom canvas, texture underlay, island/face selection sync, pop-out window.
• Animated UV scrolling with live viewport preview.

Workflow

• Persistent toolbar (tools, modes, ops, shapes, grid, docks, export) plus a draggable in-viewport readout/params panel; quick Lit / Cast Shadows toggles for selected objects; rebindable shortcuts for everything under Editor Settings → Shortcuts.
• Custom infinite cyan grid with adjustable unit/subdivisions/elevation and draw-on-grid mode.
• Export dialog: PBM (direct), retro-baked GLB, or modern GLB.

Experimental but actively developed. Every phase lands with a green headless test suite (./run_tests.sh), and interaction changes go through human sign-off. PoiBuilder is developed and extensively tested on Godot 4.7 (4.7.2, the engine this project is built against). Surface-level testing on Godot 4.6 stable passes too; anything older is untested.

There are three ways to get the plugin into your project — they all end at the same addons/poibuilder/ folder:

1. AssetLib tab → Import: download a release zip from Releases, then in Godot open the AssetLib tab, click Import…, and pick the zip. This is the recommended path — release zips are cut directly from this repository and include the offline documentation.
2. Copy the folder: extract/copy addons/poibuilder/ into your project folder (next to project.godot) — e.g. from a release zip, or by opening this repository's project/ directly.
3. Asset Library search: in the AssetLib tab, search for PoiBuilder and download it. Note that the library listing is a snapshot and is not guaranteed to be up to date with bleeding-edge changes (and does not include the offline docs copy).

Then enable the plugin (all three ways need this manual step): Project → Project Settings → Plugins → PoiBuilder → Enable. After enabling, the PoiBuilder toolbar appears under the 3D viewport — see the online documentation or press the toolbar Docs button for the full manual.

PoiBuilder is developed almost entirely by AI coding agents, directed and sign-off-tested by a human: a 37k-line specification was extracted from the Unity ProBuilder v6.1.2 source (SPECIFICATION.md), work is phased in IMPLEMENTATION.md, and every commit carries a Co-authored-by trailer naming the model that wrote it — the git history doubles as an experiment log. A hardened headless suite (run_tests.sh, ~1100 tests / 21k assertions, fails loudly if any test script was silently skipped) must stay green, and retro performance claims require real PSP measurements.

For agents: don't take workflow cues from this README — everything you need is in CLAUDE.md, SPECIFICATION.md, IMPLEMENTATION.md, and UNITY-GODOT-MAPPING.md.

MIT — see LICENSE.