Direct3D - Curve becomes faceted when selected

[davidcockey]

Using Direct3D Rhino WIP, 9.0.25252.12305
Curves become visibly faceted when selected. Non-selected curves remain visibly smooth. Curves revert to visibly smooth when no longer selected.
Sel;ected curves remain visibly smooth using OpenGL.

The curves in this example are single span, degree 3 non-rational, 9,9 units in length.
CurveSelectFacets.3dm (47.0 KB)

Rhino 9 SR0 2025-9-9 (Rhino WIP, 9.0.25252.12305, Git hash:master @ 4524dc42845a441deb0b79e431b2341582e48f2b)
License type: Commercial, build 2025-09-09
License details: Cloud Zoo
Expires on: 2025-10-24

Windows 11 (10.0.26100 SR0.0) or greater (Physical RAM: 64GB)
.NET 9.0.9

Computer platform: DESKTOP

Standard graphics configuration using DirectX
Primary display: NVIDIA GeForce RTX 2080 Ti (NVidia) Memory: 11GB, Driver date: 9-5-2025 (M-D-Y). DirectX(11)
> Accelerated graphics device with 4 adapter port(s)
- Windows Main Display attached to adapter port 0

Secondary graphics devices.
None found.

DirectX Settings
Safe mode: Off

OpenBLAS: OpenBLAS 0.3.29 DYNAMIC_ARCH NO_AFFINITY Haswell MAX_THREADS=64.

Rhino plugins that do not ship with Rhino

Rhino plugins that ship with Rhino
C:\Program Files\Rhino 9 WIP\Plug-ins\Commands.rhp “Commands” 9.0.25252.12305
C:\Program Files\Rhino 9 WIP\Plug-ins\rdk.rhp “Renderer Development Kit”
C:\Program Files\Rhino 9 WIP\Plug-ins\UpdatesAndStatistics\UpdatesAndStatistics.rhp “UpdatesAndStatistics” 9.0.25252.12305
C:\Program Files\Rhino 9 WIP\Plug-ins\RhinoRenderCycles.rhp “Rhino Render” 9.0.25252.12305
C:\Program Files\Rhino 9 WIP\Plug-ins\rdk_etoui.rhp “RDK_EtoUI” 9.0.25252.12305
C:\Program Files\Rhino 9 WIP\Plug-ins\NamedSnapshots.rhp “Snapshots”
C:\Program Files\Rhino 9 WIP\Plug-ins\MeshCommands.rhp “MeshCommands” 9.0.25252.12305
C:\Program Files\Rhino 9 WIP\Plug-ins\RhinoCycles.rhp “RhinoCycles” 9.0.25252.12305
C:\Program Files\Rhino 9 WIP\Plug-ins\Toolbars\Toolbars.rhp “Toolbars” 9.0.25252.12305
C:\Program Files\Rhino 9 WIP\Plug-ins\3dxrhino.rhp “3Dconnexion 3D Mouse”
C:\Program Files\Rhino 9 WIP\Plug-ins\Displacement.rhp “Displacement”
C:\Program Files\Rhino 9 WIP\Plug-ins\Calc.rhp “Calc”
C:\Program Files\Rhino 9 WIP\Plug-ins\SectionTools.rhp “SectionTools”

[martinsiegrist]

Coarse wire display when not selected

I extracted the boundary of the longer surface and rebuilt the two long bottom edges with 16 points, what rebuild suggested and used sweep2 to make a new tunnel. Looks better. Guess this is not about the surface so I deleted the surface and kept just two curves in the file. [image] [image] [image] When viewed more from the top, the facetting effect is not visible… Latest WIP with Direct3D 2025-09-04_Tess_mrtn.3dm (116.3 KB)

[davidcockey]

@Coarse wire display when not selected

I extracted the boundary of the longer surface and rebuilt the two long bottom edges with 16 points, what rebuild suggested and used sweep2 to make a new tunnel. Looks better. Guess this is not about the surface so I deleted the surface and kept just two curves in the file. [image] [image] [image] When viewed more from the top, the facetting effect is not visible… Latest WIP with Direct3D 2025-09-04_Tess_mrtn.3dm (116.3 KB)

This is different than my report but probably related. What I am seeing is based on whether the curve is selected or not.

[stevebaer]

Thanks; I’m experimenting with some optimizations for curve drawing under Direct3D and it looks like we are seeing some cases where the optimization is a bit too aggressive.

[davidcockey]

I would like the display fidelity to independent of whether the object is selected or not.

[stevebaer]

Of course; the goal is to not display kinks under any condition

[encephalon]

@stevebaer

the goal is to not display kinks under any condition

.

this one was set to future 2 years ago

Parabola / Curve Display issue

when i create a Parabola, the displayed curve exhibits a polyline like appearance most noticeable at the vertex, changing to degree 3 exhibits the same issue changing to degree 4 the issue disappears. tested in v7 and v8 [Bildschirm­foto 2023-10-30 um 15.00.49]

[stevebaer]

I was actually just thinking about that one and may be able to apply one of the techniques I’m experimenting with in Direct3D over in Metal to make that issue work.