Bad curve viewport rendering #37860

New Issue

Daniel Salazar · 2013-12-19T00:00:19+01:00

Daniel Salazar commented

2013-12-19 00:00:19 +01:00

System Information
openSUSE 12.3 64bits

Blender Version
Broken: Blender 2.69.7 d7033d5

Short description of error
Crappy viewport rendering on curves

Exact steps for others to reproduce the error
Press F12 CurveError.blend
Looks gorgeous
Esc and press Shift+Z to enable viewport rendering
Looks hideous

**System Information** openSUSE 12.3 64bits **Blender Version** Broken: Blender 2.69.7 d7033d5 **Short description of error** Crappy viewport rendering on curves **Exact steps for others to reproduce the error** Press F12 [CurveError.blend](https://archive.blender.org/developer/F46199/CurveError.blend) Looks gorgeous Esc and press Shift+Z to enable viewport rendering Looks hideous

Daniel Salazar commented

2013-12-19 00:00:19 +01:00

Changed status to: 'Open'

Daniel Salazar commented

2013-12-19 00:00:19 +01:00

Added subscriber: @zanqdo

Daniel Salazar changed title from ~~Bad curve viewport rendering on Cycles~~ to Bad curve viewport rendering

2013-12-19 00:17:50 +01:00

Brecht Van Lommel commented

2013-12-19 00:23:25 +01:00

Changed status from 'Open' to: 'Archived'

Brecht Van Lommel closed this issue

2013-12-19 00:23:25 +01:00

Brecht Van Lommel self-assigned this 2013-12-19 00:23:25 +01:00

Brecht Van Lommel commented

2013-12-19 00:23:25 +01:00

This is a precision issue, for which there is no simple fix unfortunately:
http://wiki.blender.org/index.php/Dev:2.6/Source/Render/Cycles/KnownIssues#Open

Basically what happens here is that you have scaled the curve to near zero on the Z axis, and the faces now almost overlap. Viewport render uses instancing for all object to allow quick editing, but this has less precision. The workaround is to avoid setting the scale so low or use Static BVH in the viewport. I need to find the time to rewrite the intersection code to be more precise, but this is tricky because it also risks losing performance.

This is a precision issue, for which there is no simple fix unfortunately: http://wiki.blender.org/index.php/Dev:2.6/Source/Render/Cycles/KnownIssues#Open Basically what happens here is that you have scaled the curve to near zero on the Z axis, and the faces now almost overlap. Viewport render uses instancing for all object to allow quick editing, but this has less precision. The workaround is to avoid setting the scale so low or use Static BVH in the viewport. I need to find the time to rewrite the intersection code to be more precise, but this is tricky because it also risks losing performance.

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Bad curve viewport rendering #37860