FreePencil2 Draws Blender Lines in One Click

For those who don’t know the tool: FreePencil2 is Masamune Sakaki’s GPL-licensed add-on for Blender. It sits between 3D scene preparation and Blender’s compositor, automatically painting vertex-colour regions and converting their boundaries into lines, with manual vertex-paint correction available when automation develops artistic opinions.

Colour first, draw later

FreePencil2 takes a 3D model, automatically separates it into vertex-colour regions and uses those colour boundaries for edge detection in Blender’s compositor. The difficult part of that approach is deciding how the model should be divided in the first place, so the add-on handles the preprocessing: analysing angles, separating neighbouring regions, merging tiny areas, differentiating touching parts and using rig information for bone-level separation.

Pressing the full automatic setup button runs the colouring stage and builds the compositor setup. Artists can then repaint regions, add lines or remove them manually. One click gets you to the drawing. It does not, mercifully, insist that one click constitutes final art direction.

The benchmark has polygons

The developer’s Blender 4.5 tests put a 50,000-polygon mechanical model at about 8.7 seconds, a 420,000-polygon tank at about 19.4 seconds and a 1.28-million-polygon steam locomotive at about 28 seconds. Those are developer measurements rather than independent benchmarks, but they give the tool a more useful scale than the traditional technical specification of “pretty fast.”

The current 2.7.0 code also lowers the default line-sensitivity setting so boundaries that previously fell below the detection threshold are more likely to appear. Existing scenes can therefore render differently unless the sensitivity is returned to its earlier value.

Mind the Blender version

FreePencil2 supports Blender 4.2, 4.3, 4.5 and 5.2, with 4.5 and 5.2 recommended. Blender 4.2 can render the result but lacks live viewport preview because its viewport compositor does not evaluate the required AOV output. Blender 4.1 and earlier are unsupported.

Free source, assembly required

The source repository is licensed GPL-3.0-or-later. GitHub provides the code, but not a ready-to-install release ZIP; users following the repository route need to build the extension package with Blender’s command line. Sakaki also offers a separate distribution through note with a prepared ZIP, Japanese documentation and support.

So yes, the line art can be one click. Getting the one-click button from GitHub involves slightly more than one click. Software remains consistent in its sense of humour. Studios should test FreePencil2 on representative production models, materials and target Blender versions before deploying it into an active pipeline.

https://github.com/megamarsun/FreePencil2/

https://github.com/megamarsun/FreePencil2/blob/main/CHANGELOG.md