"Porcupine" extra lines graphical bug?

Strange extra lines are now appearing for me in wireframe and shaded modes. Here’s a video of moving the camera around a sphere.

I’m on Rhino Version 6 (6.24.20079.23332, 2020-03-19), Catalina 10.15.4 (19E287). This started happening after upgrading Catalina yesterday, so I suspect that the new OS version has caused this. Doing a full uninstall (as in https://wiki.mcneel.com/rhino/mac/uninstall) and reinstall did not change the behaviour.

We have seen this on some older iMacs running older display adapters.
It could be something else.

Please run the SystemInfo command in Rhino and post the results.
It’s a fair amount of text.

Thanks

Here is my SystemInfo:

Rhino 6 SR24 2020-3-19 (Public Build, 6.24.20079.23332, Git hash:master @ 064283610b834170e52117f2656605b5b25d65c0)
License type: Educational, build 2020-03-19
License details: Cloud Zoo. In use by: henryseg ()

Apple Intel 64-bit macOS Version 10.15.4 (Build 19E287) (Physical RAM: 64Gb)
Mac Model Identifier: MacBookPro16,1
Machine name: MacBook Pro
Language: en-US (MacOS default)

AMD Radeon Pro 5500M OpenGL Engine (OpenGL ver:4.1 ATI-3.8.24)

OpenGL Settings
Safe mode: Off
Use accelerated hardware modes: On
Redraw scene when viewports are exposed: On

Anti-alias mode: 4x
Mip Map Filtering: Linear
Anisotropic Filtering Mode: Height

Vendor Name: ATI Technologies Inc.
Render version: 4.1
Shading Language: 4.10
Maximum Texture size: 16384 x 16384
Z-Buffer depth: n/a
Maximum Viewport size: 16384 x 16384
Total Video Memory: 8 GB
Graphics: AMD Radeon Pro 5500M
Displays: Color LCD (264dpi 2x), Unknown (144dpi 2x)

Graphics processors
Intel UHD Graphics 630 (1536 MB)
AMD Radeon Pro 5500M (8 GB)
Color LCD (1792 x 1120 @ 59 Hz)

USB devices
Apple Inc.: USB3.0 Hub
Apple Inc.: iPad
Apple Inc.: iPhone
Apple Inc.: USB-C Digital AV Multiport Adapter
Apple: composite_device
Apple Inc.: Touch Bar Backlight
Apple Inc.: Touch Bar Display
Apple Inc.: Apple Internal Keyboard / Trackpad
Apple: Headset
Apple Inc.: Ambient Light Sensor
Apple Inc.: FaceTime HD Camera (Built-in)
Apple Inc.: Apple T2 Controller

Bluetooth devices
None

Third party kernel extensions
com.getdropbox.dropbox.kext (1.10.3) F29DD0CB-48D6-311A-9B69-E39CF775493C

Third party plugins
/usr/lib/swift/libswiftCore.dylib
/usr/lib/swift/libswiftCoreFoundation.dylib
/usr/lib/swift/libswiftCoreGraphics.dylib
/usr/lib/swift/libswiftDarwin.dylib
/usr/lib/swift/libswiftDispatch.dylib
/usr/lib/swift/libswiftFoundation.dylib
/usr/lib/swift/libswiftIOKit.dylib
/usr/lib/swift/libswiftObjectiveC.dylib
/usr/lib/swift/libswiftXPC.dylib
/usr/lib/swift/libswiftCryptoTokenKit.dylib
/usr/lib/swift/libswiftos.dylib
/usr/lib/log/liblog_network.dylib

Rhino plugins
/Applications/Rhinoceros.app/Contents/Frameworks/RhMaterialEditor.framework “Renderer Development Kit” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/Commands.rhp “Commands” 6.24.20079.23332
/Applications/Rhinoceros.app/Contents/PlugIns/NamedSnapshots.rhp “Snapshots” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/Import_OBJ.rhp “Import_OBJ” 6.24.20079.23332
/Applications/Rhinoceros.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/export_XAML.rhp “export_xaml” 6.24.20079.23332
/Applications/Rhinoceros.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/Export_OBJ.rhp “export_OBJ” 6.24.20079.23332
/Applications/Rhinoceros.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/RDK_EtoUI.rhp “RDK_EtoUI” 6.24.20079.23332
/Applications/Rhinoceros.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/export_SVG.rhp “Export SVG” 6.24.20079.23332
/Applications/Rhinoceros.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/MeshCommands.rhp “MeshCommands” 6.24.20079.23332
/Applications/Rhinoceros.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/Export_DAE.rhp “Export_DAE” 6.24.20079.23332
/Applications/Rhinoceros.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/export_PDF.rhp “PDF Export” 6.24.20079.23332
/Applications/Rhinoceros.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/export_IGES.rhp “IGES Export Plug-in” 6.24.20079.23332
/Applications/Rhinoceros.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/Import_SVG.rhp “Import_SVG” 6.24.20079.23332
/Applications/Rhinoceros.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/BlockEdit.rhp “BlockEdit” 6.24.20079.23332
/Applications/Rhinoceros.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/Export_AMF.rhp “Export_AMF” 6.24.20079.23332
/Applications/Rhinoceros.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/import_DST.rhp “Import_DST” 6.24.20079.23332
/Applications/Rhinoceros.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/export_PLY.rhp “PLY - Polygon File Format Export” 6.24.20079.23332
/Applications/Rhinoceros.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/Import_AMF.rhp “Import_AMF” 6.24.20079.23332
/Applications/Rhinoceros.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/RhinoCycles.rhp “RhinoCycles” 6.24.20079.23332
/Applications/Rhinoceros.app/Contents/PlugIns/export_SKP.rhp “SketchUp Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/Export_UDO.rhp “Moray Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/import_RAW.rhp “RAW Triangle Import” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/Import_DGN.rhp “MicroStation file import: import_DGN” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/import_VRML.rhp “VRML Import” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/AnimationTools.rhp “AnimationTools” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/Import_WAMIT.rhp “WAMIT import” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/NamedPositions.rhp “Named Position” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/import_SKP.rhp “SketchUp Import” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/Export_RAW.rhp “Raw Triangles Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/MPlane.rhp “MPlane” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/Export_XGL.rhp “XGL Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/RhinoRender.rhp “Rhino Render” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/Export_CD.rhp “Cult3D Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/export_LWO.rhp “Lightwave Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/export_SLC.rhp “SLC Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/import_3MF.rhp “import_3MF” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/export_STEP.rhp “STEP Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/export_3MF.rhp “export_3MF” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/Export_WAMIT.rhp “WAMIT Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/Import_SLC.rhp “SLC Import” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/Import_OFF.rhp “OFF Import” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/Squish.rhp “Squish” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/Export_X_T.rhp “Parasolid Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/RhinoBonusTools.rhp “Rhino Bonus Tools” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/RhinoLabsTools.rhp “Rhino Labs Tools” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/Import_M.rhp “Import_M” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/Import_X.rhp “X Import” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/import_IGES.rhp “IGES Import Plug-in” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/export_AI.rhp “Adobe Illustrator Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/export_ACAD.rhp “AutoCAD file export : export_ACAD” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/Displacement.rhp “Displacement” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/import_LWO.rhp “Lightwave Import” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/export_SAT.rhp “ACIS Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/Export_CSV.rhp “Comma Separated Value Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/import_PDF.rhp “PDFReader” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/export_STL.rhp “STL Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/import_VDA.rhp “VDA Import” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/import_STEP.rhp “STEP Import” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/export_FBX.rhp “Export_FBX” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/Import_SolidWorks.rhp “Solidworks Import” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/import_STL.rhp “STL Import” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/Export_RIB.rhp “Renderman Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/import_FBX.rhp “Import_FBX” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/export_Points.rhp “Points Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/export_VDA.rhp “VDA Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/import_ACAD.rhp “AutoCAD file import: import_ACAD” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/Export_X.rhp “X Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/CreaseAngle.rhp “CreaseAngle” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/export_3DS.rhp “3D Studio Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/import_PLY.rhp “PLY - Polygon File Format Import” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/MeshTools.rhp “MeshTools” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/import_Points.rhp “Points Import” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/PanelingTools.rhp “PanelingTools” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/MeshFromPoints.rhp “MeshFromPoints” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/export_VRML.rhp “VRML/X3D Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/Import_GTS.rhp “GTS Triangle Import” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/SolidTools.rhp “SolidTools” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/Export_GTS.rhp “GTS Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/PlugIns/Export_POV.rhp “POV-Ray Export” 6.24.20079.1002
/Applications/Rhinoceros.app/Contents/Frameworks/RhCore.framework/Resources/ManagedPlugIns/RhinoDLR_Python.rhp “IronPython” 6.24.20079.23332
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Hmm…
That’s odd. I don’t see anything that I would call a problem.
The “unknown” display is strange.
As a test, If you temporarily switch to a single monitor, does that make any difference?

@dan
@jeff
Any ideas on this one?

Ah interesting, I was using an iPad Pro with Sidecar as a second monitor connected by USB: removing that and restarting the computer removes the porcupine effect and it’s back to normal.

I’ve been hearing that the iPad/Sidecar setup is a bit dodgy.
At least you know what it is now and not a problem with the model.