Volume Preserving Smoothing (Gumroad)

Addon for Blender 3.6 or 4.0.1 and up - smoothing mesh surfaces without volume loss. Since ver 2.3 update there is also 'Volume smooth brush' tool (has geometry sliding option) available in edit mode.

Video guide - bit old - there was no smooth brush yet.

Volume Preserving Smoothing considers sharp edges as guiding rails for vertices to move along, allowing the preservation of the primary forms of the smoothed object. This feature helps maintain the overall shape and structure of the smoothed object.

To access the smoothing operator (works on whole mesh or selection): open mesh context menu with W key in mesh edit mode, then select Mesh Smoothing visible at the very bottom, and pick mode:

• Inflate smoothing - good for round surfaces
• Laplacian HC smoothing - fast but sometimes give artifacts
• Volume smoothing - slower but best quality

To use smooth brush: open left tools sidebar (T - key in 3D View), enable 'Volume smooth tool' icon - usually at the very bottom of tools list.

Features:

• smooth mesh while maintaining main object shape (operator and brush)
• border mesh vertices will slide along border edges, this prevents shrinking of mesh outline
• smooth brush support pulling/sliding of geometry along surface of mesh
• X axis symmetry is supported
• works with shape-keys

• you have ability to define sliding rail edges (edges marked as sharp) - they constrain sliding of geometry

• three edge tension methods (Uniform, Proportional to edge length, Inverse to edge length)
• optimized with NUMPY

To make edge into rail edge - just mark edge loop as sharp. Now verts belonging to this edge, will move only along edge.

Update 1.1 + 1.2 + 1.3:

* improved speed around 60%, plus bug fix.

Update 1.4:

• you can increase iterations amount above 20 (by manually entering bigger value)
  

Update 2.0 (08.12.2018):

• Added support for blender 2.8 in version 2.0 of addon.
  

Update 2.1 (blender 2.8) (14.03.2019):

• Support for symmetrical smoothing when using 'mirror' option in mesh edit mode.
• bugfixes for latest daily blender builds
  

Update 2.3 (blender 2.8) (31.12.2019):

• fix verts on symmetry not being smoothed correctly
• added smooth brush for mesh edit mode

Update 2.4 (blender 2.8) (03.01.2020):

• better algorithm for brush size adjusting from F key

• fix bad smoothing radius influence when object has no scale applied
  

Update 2.5 (blender 2.93) (28.01.2020):

• added option for pulling/sliding geometry
• exposed more parameters in smooth tool - backface mask, locking border, smoothing face proportions
  

Update 2.5.1 (02.07.2021)

•  tweak behavior of freeze selection border - in brush mode

Update 2.5.2 (17.01.2022)

• nicer brush outline for smooth tool
• fixed smoothing behavior when brush moved outside of mesh
• fixed smooth brush not working in some cases

Update 2.5.3 (16.05.2022)

• fix brush outline for scaled objects
• added auto-updater in add-on preferences

Last update 2.6.0 (28.07.2023) - For Blender 3.6 and up

• added ability to work on very small objects (minimum brush size is now linked to 0.001 of object size),
• Moved from old bgl module to gpu module (from now on only blender 3.6 and up will be supported)

Last update 2.7.0 ( 22.10.2023 - For Blender 3.6, 4.x)

• Added support for Blender 4.0,
• Moved from old bgl module to gpu module (from now on only blender 3.6 and up will be supported)

Last update 2.8.0 ( 26.11.2023 - For Blender 3.6, 4.x)

• Smooth Operators now support masking the effect by Vertex Group (see F9 Vertex Mask property)
• Adjusting Smooth brush size with F and strength with Shift+F wont move brush outline anymore (more in line with Blender brush behavior),
• Fix brush strength number not being visible in UI when adjusting it,