Surface Diagnostics

by Josef Ludvík Böhm in Scripts and Addons

... Release Log ...

2023/08/11 surface_diagnostics_1.1
- Added Curvature (mean, gaussian, min, max) and Radius (min, max) shaders, applied on active object as a GN modifier
- Dropped support for Blender 3.3 LTS, due to incompatible (geometry) nodes for Curvature/Radius shaders. Now only 3.4+
- Diagnostic shaders now applied to all selected objects, except for Curvature and Radius shaders (potentially too much performance hit)
- Curvature Graphs now applied as geometry node modifiers ON the active Object, NOT on spawned empty mesh Objects
- Removing Section/Slice override for active object no longer resets coordinates for the rest of the objects
- various bug fixes and rewrites 

2023/06/15 surface_diagnostics_1.0.2
- Backported to Blender 3.3 LTS without loss of functionality
- Possible to define "Zebra" colours
- "Sections" and "Cut" now each have separate coordinate system
- Tweaked "Sections" line thickness settings
- fixed "no Active Object" bug

2023/05/23 surface_diagnostics_1.0.1
- First stable release + bug fixes


1) Go to Menu Edit / Preferences / Add-ons.
2) Click "Install" - select file "".
3) Activate Add-on "Surface Diagnostics".

How to use (Full version)

1) In 3D Viewport Side Panel (N-key shortcut) click on "Surf Ace" Tab.
2) Click on an object to make it Active Object (SurfAce only works for active, not selected).


1) In Object/Edit mode click on any diagnostic shader to apply "Material Override" (Geometry Nodes Modifier) for current Active Object
2) Change properties in Addon UI if needed.
3) To delete overrides, you can do so for Active Object or for All Objects.
4) "High Quality Normals" is an Eevee performance option, revealed in Addon's UI. Useful for clean Zebra and Isoangle.
5) You can apply override to all selected objects, except Curvature+Radius (big potential performance hit)

Curvature Graph

Turn off :"GPU Subdivision" in Edit / Preferences / Viewport / Subdivision
if the Curvature Comb looks low resolution / crooked
1) For Mesh Objects go to Edit mode / for Curve Objects only make one Active.
2) For Mesh Objects select connected line of Vertices and click on "New CGraph".
3) Change properties if needed for given CGraph.

"Surface" CGraph type will point in Surface Normal direction.
When applied at fully creased edge, there will be 2 graphs (each for 1 surface connected to creased edge).

"Curve" CGraphs type will point in direction of local Curve curvature.
For creased edges there will be only 1 graph.

5) You can apply multiple CGraphs on single Object.
6) Modify values for individual CGraphs
7) You can Change Wire color for current Blender Theme from Addon UI to change color of CGraphs.
8) You can add / substract Selection in Blender's standard Vertex Groups menu.
9) Delete individual CGraphs, or all existing in current Blend File.

How to use (Lite version)

1) Download "Surface_Diagnostics_Assets.blend" and place in your Asset Library.
2) You can also simply link / append Nodetrees from provided Blend file.


1) Create new Geometry Node Modifier with "SD_Mat_Override" GN Nodetree for given Object.
2) Place provided Material into Modifier Input.
3) Change Material Node Group values (you can put Material into empty slot of given Object to reveal the values).
4) For Curvature/Radius shaders just assign as GN modifier

Curvature Graph

1) Create new Vertex Group for your Mesh Object and apply to row of connected Vertices.
1) Append "SD_CGraph" Geometry Nodetree from provided file.
3) Create new Geometry Nodes Modifier for it and plug in "SD_CGraph".
4) Type name of created Vertex Group into first modifier input.



- Do not apply CGraph to Faces (see FAQ - limitation of Vertex Groups)
- Color of CGraphs will change Wire color for whole Blender Theme. For Default hit Backspace while howering over the color tab.
- Performance hit for Curvature and Radius shaders with high density objects

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Sales 100+
Customer Ratings 2
Average Rating
Dev Fund Contributor
Published 4 months ago
Blender Version 3.4, 3.5
License GPL
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