Turn One Picture into a 3D Game Asset Locally (Pixal3D, TRELLIS.2, Godot)

Short answer: Make one clean picture, run it through the Pixal3D / TRELLIS.2 CosyTemplate in Promptus, and you get a painted 3D model as a GLB. Lower three settings and it takes half the time. Then cut the triangles, set the real size and export a GLB, and it runs in a game engine. No 3D experience needed, and running locally costs no credits.

1. Make it 3D

1. In Promptus, open CosyTemplates, search Pixal3D, pick version two, and choose Load in ComfyUI. The first load may download about 14 GB of models.
2. In Load Image, click the file name and pick your picture. The template removes the background for you.
3. Set the model switch: false is Pixal3D, true is TRELLIS.2.
4. Press Run. The working node lights up as it goes left to right.

The finished model appears in the 3D preview and is saved as a GLB in the ComfyUI output folder, inside 3D.

How it works

1. Cut-out: BiRefNet separates the object from the background.
2. Camera: MoGe estimates where the picture was taken from.
3. Blocks: a rough shape, like building it in Lego.
4. Refine: smaller blocks, then a smooth surface at up to 1536 resolution.
5. Paint: colours all the way round — even the back it never saw.

Better pictures

The 3D model only sees your picture, so the picture does half the work. Rules: one object, centred, on a plain background; the whole object in frame; soft even light; a three-quarter view. In Playground, switch Z-Image Turbo to Local (online uses credits) and write the rules into the prompt: a wooden treasure chest, one object centered, 3/4 view, whole chest in frame, on a plain light gray background, soft even studio light. It took 17 seconds.

Pick a model, and make it faster

Hunyuan3D 2.1’s licence doesn’t cover the UK, the EU or South Korea — check it before you use it. On a small card or a Mac, use Run online from the template menu; it uses credits.

What game-ready means

• Triangles: the raw chest had almost 700,000; a game redraws every one each frame. Decimate to about 20,000 — 97% fewer, same shape.
• UV map: the model unfolded flat so a picture can wrap round it. The template makes it.
• PBR maps: base colour (paint), roughness (shiny or matte), metallic, and a normal map that fakes small bumps.
• Real size: GLB works in metres — this chest is 60 cm wide.
• All of it in one GLB.

Clean-up in Blender

1. File › Import › glTF and pick the GLB. Turn on Overlays › Statistics: 696,717 triangles.
2. Add Modifier › Generate › Decimate. Ratio = 20,000 ÷ 697,000 ≈ 0.0287 → 19,995 triangles. Ctrl+A over the modifier to apply.
3. Press N, scale to 60 cm wide, move it onto the floor, then Ctrl+A › All Transforms.
4. File › Export › glTF, format GLB.

With the fast settings the chest is already about 20,000 triangles, so you can skip the decimate.

Into the game: Godot

1. Create a project, copy the GLB into the project folder; Godot imports it and pulls out the three texture maps.
2. Make a 3D scene, drag the chest in, set its position to zero.
3. Add the sun and sky (DirectionalLight and WorldEnvironment) and a Camera3D; Align Transform with View.
4. Attach a script with rotate_y(delta * 0.6) in _process, save and press F6.

Mistakes and fixes

Next: make a rigged character that walks in Unity. Models: Pixal3D (MIT), TRELLIS.2 (MIT); tools: Blender, Godot. Download Promptus.