A free and open-source pipeline

You can make a complete game environment, from first blockout to a lit scene in an engine, without paying for software or accepting a licence that limits commercial use. This guide sets out one such pipeline, tool by tool, with the licence of each and the file that passes from one step to the next.

For what open-source licences mean in general, see software licensing explained. For the full range of paid and free options in each category, see choosing tools: an overview.

#Tools in the pipeline

Free asset libraries can supply supporting assets. Poly Haven and ambientCG release everything under CC0, so you may use, modify and sell work containing their assets without credit (polyhaven.com: License; ambientCG documentation: License). See asset libraries and asset licences.

#Example asset: a stone well

This example follows a stone well for a medieval courtyard, made entirely with the tools above.

1. Reference and concept. Collect photos and paint a quick value sketch in Krita. See gathering and using reference.
2. Blockout. Model the well's primary shapes in Blender at real scale, or block the whole courtyard in TrenchBroom first. See blockout.
3. High poly. Sculpt the stones in Blender's Sculpt Mode with multiresolution and subdivision levels for detail.
4. Low poly and UVs. Retopologise or decimate, unwrap, and check with a checker.
5. Bake. Bake normal, ambient occlusion and curvature in Blender. See baking.
6. Materials. Build a tileable stone in Material Maker for the courtyard floor, and paint the well itself with Ucupaint in Blender or in ArmorPaint, starting from CC0 surfaces from Poly Haven or ambientCG.
7. Pack channels. Combine occlusion, roughness and metallic into one image in Krita or GIMP. See channel packing.
8. Export. Export from Blender as glTF. Blender reads base colour, metallic and roughness straight from the Principled BSDF node (Blender Manual: glTF 2.0). See glTF.
9. Engine. Import into Godot. Godot recommends glTF 2.0, and can also import .blend files directly by calling Blender in the background (Godot Engine documentation: Available 3D formats).

#Limitations of an open pipeline

An open pipeline is complete, but some steps are harder than in the commercial standard tools:

• 3D painting. ArmorPaint and Ucupaint cover layer-based painting (CG Channel: ArmorPaint 1.0 is out; Blender Extensions: Ucupaint), but most breakdowns you will learn from use Substance 3D Painter, so tutorials will not map one-to-one.
• Procedural materials. Material Maker covers node-based materials (CG Channel: Material Maker 1.4 released); Substance 3D Designer has a far larger tutorial ecosystem.
• Sculpting references. Blender's Sculpt Mode handles environment work, but almost every sculpting breakdown cited on digital sculpting uses ZBrush, so you will often translate brush names.
• Engine familiarity. Godot teaches the same principles as Unreal and Unity, but not the same editor; see game engines.

#Common mistakes

• Mixing licences without checking. A free tool is not always open source, and a free asset is not always CC0. Check each one; see software licensing explained and asset libraries and asset licences.
• Exporting procedural shaders and expecting them to arrive. Bake to images before exporting glTF (Blender Manual: glTF 2.0).
• Assuming every team member has Blender. Godot's direct .blend import needs Blender installed on every machine that imports the project (Godot Engine documentation: Available 3D formats).

#Further reading and watching