Collision drastically affects shading in BI #51685

New Issue

Serge Lyatin · 2017-05-31T22:33:17+02:00

Serge Lyatin commented

2017-05-31 22:33:17 +02:00

System Information
Win7 64

Blender Version
Broken: 2.78a

Short description of error
Render produces different shading for two objects which are sharing same mesh data. But one object has got Collision modifer, another - doesn't.

Exact steps for others to reproduce the error
I know, that you are not developing BI anymore, but anyway. Render file, then check/uncheck Switch node checkbox to see the difference.
Collision_render_artifact.blend

**System Information** Win7 64 **Blender Version** Broken: 2.78a **Short description of error** Render produces different shading for two objects which are sharing same mesh data. But one object has got Collision modifer, another - doesn't. **Exact steps for others to reproduce the error** I know, that you are not developing BI anymore, but anyway. Render file, then check/uncheck Switch node checkbox to see the difference. [Collision_render_artifact.blend](https://archive.blender.org/developer/F614629/Collision_render_artifact.blend)

Serge Lyatin commented

2017-05-31 22:33:17 +02:00

Changed status to: 'Open'

Serge Lyatin commented

2017-05-31 22:33:17 +02:00

Added subscriber: @SergeL

Bastien Montagne commented

2017-06-01 09:13:31 +02:00

Added subscriber: @mont29

Bastien Montagne commented

2017-06-01 09:13:31 +02:00

Changed status from 'Open' to: 'Archived'

Bastien Montagne closed this issue

2017-06-01 09:13:31 +02:00

Bastien Montagne self-assigned this 2017-06-01 09:13:31 +02:00

Bastien Montagne commented

2017-06-01 09:13:31 +02:00

That’s no bug, afaik no render engine survives well to coplanar faces… Numerical imprecision just makes it impossible to decide which face is visible for which pixel, generates auto-shadowing, etc.

Serge Lyatin commented

2017-06-01 12:18:46 +02:00

Sorry, but I don't understand how the same mesh has different shading due to collision modifier, which does nothing in this case. Also Cycles produce the same shading with or without Collision modifier.

Bastien Montagne commented

2017-06-01 14:30:18 +02:00

Changed status from 'Archived' to: 'Open'

Bastien Montagne reopened this issue

2017-06-01 14:30:18 +02:00

Bastien Montagne commented

2017-06-01 14:30:18 +02:00

Eeeeek! Ok, totally completely misunderstood the report here, sorry!

Now, issue here is with triangulation, looks like collision modifier can affect base mesh in some cases, yuck. :/

Eeeeek! Ok, totally completely misunderstood the report here, sorry! Now, issue here is with triangulation, looks like collision modifier can affect base mesh in some cases, yuck. :/

Bastien Montagne removed their assignment 2017-06-01 16:51:09 +02:00

Bastien Montagne commented

2017-06-01 16:51:09 +02:00

Added subscriber: @ideasman42

Bastien Montagne commented

2017-06-01 16:51:09 +02:00

Tried to understand what’s going on here for quite some time now, and… am running out of idea.

Issue is not with Collision modifier, that one does not affect DM data at all - and anyway, tried emptying its evaluation function and changed nothing.

So am assuming issue is somewhere in modifiers stack evaluation itself (aka mesh_calc_modifiers()), but could not pinpoint any differences here… Imho it's either tessellating issue, or poly normal issue, but both seem to be handled exactly the same way in both cases. @ideasman42 may have more ideas/insight?

Tried to understand what’s going on here for quite some time now, and… am running out of idea. Issue is not with Collision modifier, that one does not affect DM data at all - and anyway, tried emptying its evaluation function and changed nothing. So am assuming issue is somewhere in modifiers stack evaluation itself (aka `mesh_calc_modifiers()`), but could not pinpoint any differences here… Imho it's either tessellating issue, or poly normal issue, but both seem to be handled exactly the same way in both cases. @ideasman42 may have more ideas/insight?

Germano Cavalcante commented

2019-10-28 14:22:11 +01:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2019-10-28 14:22:11 +01:00

Changed status from 'Open' to: 'Resolved'

Germano Cavalcante closed this issue

2019-10-28 14:22:11 +01:00

Germano Cavalcante self-assigned this 2019-10-28 14:22:11 +01:00

Germano Cavalcante commented

2019-10-28 14:22:11 +01:00

I can't reproduce the problem in blender 2.79, so I suppose this has already been fixed.

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Collision drastically affects shading in BI #51685