ZBuff glitch in Internal renderer #44950

New Issue

Alexey · 2015-06-04T13:52:32+02:00

Alexey commented

2015-06-04 13:52:32 +02:00

System Information
windows7 64
ASUS ATI Radeon HD6870

Blender Version
Broken: (2.71 and all later)
Worked: (2.70 and all earlier)

Short description of error
i don't know how to repeat this bug and upload blend file with result

Exact steps for others to reproduce the error
unknown error.blend

System Information windows7 64 ASUS ATI Radeon HD6870 Blender Version Broken: (2.71 and all later) Worked: (2.70 and all earlier) **Short description of error** i don't know how to repeat this bug and upload blend file with result **Exact steps for others to reproduce the error** [unknown error.blend](https://archive.blender.org/developer/F184725/unknown_error.blend) ![1r.png](https://archive.blender.org/developer/F184726/1r.png) ![r2.png](https://archive.blender.org/developer/F184728/r2.png) ![r3.png](https://archive.blender.org/developer/F184731/r3.png)

Alexey commented

2015-06-04 13:52:32 +02:00

Changed status to: 'Open'

Alexey commented

2015-06-04 13:52:32 +02:00

Added subscriber: @Inwader77

Bastien Montagne commented

2015-06-04 14:20:18 +02:00

Added subscriber: @mont29

Bastien Montagne commented

2015-06-04 14:20:18 +02:00

Looks like some glitch in internal engine (Cycles is not affected), probably something like float precision issue?

Triangulating the quad in Edit mode, is new edge is (bottom left, top right) issue persists, other edge 'fixes' it.
Only visible with ortho camera at this scale value too.
Any small scale/rotate/move (except along Z axis) fixes it.

Looks like some glitch in internal engine (Cycles is not affected), probably something like float precision issue? * Triangulating the quad in Edit mode, is new edge is (bottom left, top right) issue persists, other edge 'fixes' it. * Only visible with ortho camera at this scale value too. * Any small scale/rotate/move (except along Z axis) fixes it.

Bastien Montagne changed title from ~~Unknown render error~~ to ZBuff glitch in Internal renderer

2015-06-04 16:33:14 +02:00

Bastien Montagne commented

2015-06-04 16:35:16 +02:00

More facts:

Bug happens in zbuffer code of internal (somewhere in zbuffer_solid(), in zbuf.c).
Bug is also related to render size (render scale of 30% or less shows it, 31% and above doesn’t).

More facts: * Bug happens in zbuffer code of internal (somewhere in `zbuffer_solid()`, in zbuf.c). * Bug is also related to render size (render scale of 30% or less shows it, 31% and above doesn’t).

Alexey commented

2015-06-04 20:35:31 +02:00

In #44950#313473, @mont29 wrote:
More facts:

Bug happens in zbuffer code of internal (somewhere in zbuffer_solid(), in zbuf.c).

Bug is also related to render size (render scale of 30% or less shows it, 31% and above doesn’t).

and else, if we change orto scale in camera and then return to 3.124 handly(not ctrl+Z) - working properly

> In #44950#313473, @mont29 wrote: > More facts: > * Bug happens in zbuffer code of internal (somewhere in `zbuffer_solid()`, in zbuf.c). > * Bug is also related to render size (render scale of 30% or less shows it, 31% and above doesn’t). and else, if we change orto scale in camera and then return to 3.124 handly(not ctrl+Z) - working properly

Sergey Sharybin commented

2015-06-05 12:14:29 +02:00

Added subscriber: @Sergey

Sergey Sharybin self-assigned this 2015-06-05 12:14:29 +02:00

Sergey Sharybin commented

2015-06-05 12:14:29 +02:00

Things are a bit crazy here. Will have a closer look over the weekend. Assigning to self so it's on the radars.

Ton Roosendaal commented

2015-06-15 19:20:31 +02:00

Added subscriber: @Ton

Ton Roosendaal commented

2015-06-15 19:20:31 +02:00

Wow, this is the error in clipping code I wrote in early 90ies. It is a numerical imprecision in comparing float values, and I never could solve it.

This only happens in extreme cases. Really rare.

Wow, this is the error in clipping code I wrote in early 90ies. It is a numerical imprecision in comparing float values, and I never could solve it. This only happens in extreme cases. Really rare.

Sergey Sharybin commented

2015-06-15 19:25:51 +02:00

Changed status from 'Open' to: 'Archived'

Sergey Sharybin closed this issue

2015-06-15 19:25:51 +02:00

Sergey Sharybin commented

2015-06-15 19:25:51 +02:00

After discussion with @Ton it ended up to be a numeric instability in the clipping code.

SO thanks for the report, but closing as a TODO now: http://wiki.blender.org/index.php/Dev:2.5/Source/Development/Todo/Render#Render_Engine

After discussion with @Ton it ended up to be a numeric instability in the clipping code. SO thanks for the report, but closing as a TODO now: http://wiki.blender.org/index.php/Dev:2.5/Source/Development/Todo/Render#Render_Engine

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ZBuff glitch in Internal renderer #44950