Sketcher: vertex picking broken due to depth buffer (vertical / horizontal lines)

[supersinapsis]

Is there an existing issue for this?

• I have searched the existing issues

Version

0.21 (Development)

Full version info

Hi RealThunder,

there is a regression in Sketcher vertex picking.

Problem:
Vertices are not reliably pickable unless the sketch is rotated in perspective.
Typical cases:
- Vertical or oblique lines: only the upper vertex can be selected
- Horizontal lines: neither vertex is pickable
- Rotating the view makes the “missing” vertex selectable

This happens with:
- OpenGL enabled
- OpenGL disabled (software renderer)
So it is not a driver issue.

This strongly indicates a Z-buffer / depth-test interaction.

Location:
src/Mod/Sketcher/Gui/ViewProviderSketch.cpp

Root cause:
Vertex markers (SoMarkerSet) are depth-tested against sketch geometry,
so vertices behind or coplanar with edges fail picking.

Proposed fix:
Disable depth test for vertex markers and force SHAPE picking.

Patch (minimal):


#include <Inventor/nodes/SoDepthBuffer.h>
#include <Inventor/nodes/SoPickStyle.h>

// before PointSet creation
SoDepthBuffer* pcDepth = new SoDepthBuffer;
pcDepth->test.setValue(false);
pointsRoot->addChild(pcDepth);

SoPickStyle* pickStyle = new SoPickStyle;
pickStyle->style = SoPickStyle::SHAPE;
pointsRoot->addChild(pickStyle);

edit->PointSet = new SoMarkerSet;

Subproject(s) affected?

None

Problem description

python3 -c "
path = '/media/alejo/446GB/FreeCad2025/FreeCAD-LinkDaily/src/Mod/Sketcher/Gui/ViewProviderSketch.cpp'
with open(path, 'r') as f: content = f.read()

1. Insertar el Header (encabezado) necesario si no existe

if 'SoDepthBuffer.h' not in content:
content = content.replace('# include <Inventor/nodes/SoMarkerSet.h>', '# include <Inventor/nodes/SoMarkerSet.h>\n# include <Inventor/nodes/SoDepthBuffer.h>')

2. Definir el bloque de reparación (Fix Z-Buffer)

old = ' edit->PointSet = new SoMarkerSet;'
new = ' SoDepthBuffer * pcDepth = new SoDepthBuffer;\n pcDepth->test.setValue(false);\n pointsRoot->addChild(pcDepth);\n\n SoPickStyle* pickStyle = new SoPickStyle;\n pickStyle->style = SoPickStyle::SHAPE;\n pointsRoot->addChild(pickStyle);\n\n edit->PointSet = new SoMarkerSet;'

3. Aplicar el cambio solo si no se aplicó antes (evita duplicados)

if 'pcDepth->test.setValue(false)' not in content:
with open(path, 'w') as f: f.write(content.replace(old, new, 1))
print('✅ Reparación de vértices aplicada a LinkDaily.')
else:
print('⚠️ La reparación ya estaba aplicada anteriormente.')
"

Anything else?

No response

Code of Conduct

• I agree to follow this project's Code of Conduct