translucent objects occlude other members in group instances #48983

New Issue

Paolo Acampora · 2016-07-31T18:20:47+02:00

Paolo Acampora commented

2016-07-31 18:20:47 +02:00

System Information
all operating systems

Blender Version
Broken: 2.77 66552ca

Short description of error
Group instances do not take the "show_transparent" property into account. As a result, opaque members of a group may be occluded by translucent members. It dosn't happen every time as the drawing order depends by the group membership order, yet it may be a significant issue when using linked groups for character with glasses, or car with windows et cetera.

Internally, this is due to the dupli Base objects being temporary and therefore not able to be deferred to the transparency pass. A possible solution would be to draw only non transparent dupli members in the first pass, so that the transparent ones can be drawn afterwards.

A fix patch to help illustrating the issue
dupli_transp.diff

Exact steps for others to reproduce the error
A sample .blend file containing some grouped object and their group instance: the circle masks the monkey, but not the cube in the background when in material shading
transp_sort.blend

**System Information** all operating systems **Blender Version** Broken: 2.77 66552ca **Short description of error** Group instances do not take the "show_transparent" property into account. As a result, opaque members of a group may be occluded by translucent members. It dosn't happen every time as the drawing order depends by the group membership order, yet it may be a significant issue when using linked groups for character with glasses, or car with windows et cetera. ![transp_sort_1.jpg](https://archive.blender.org/developer/F330459/transp_sort_1.jpg) Internally, this is due to the dupli Base objects being temporary and therefore not able to be deferred to the transparency pass. A possible solution would be to draw only non transparent dupli members in the first pass, so that the transparent ones can be drawn afterwards. **A fix patch to help illustrating the issue** [dupli_transp.diff](https://archive.blender.org/developer/F330461/dupli_transp.diff) ![transp_sort_2.jpg](https://archive.blender.org/developer/F330467/transp_sort_2.jpg) **Exact steps for others to reproduce the error** A sample .blend file containing some grouped object and their group instance: the circle masks the monkey, but not the cube in the background when in material shading [transp_sort.blend](https://archive.blender.org/developer/F330460/transp_sort.blend)

Paolo Acampora commented

2016-07-31 18:20:47 +02:00

Changed status to: 'Open'

Paolo Acampora commented

2016-07-31 18:20:47 +02:00

Added subscriber: @PaoloAcampora

Campbell Barton commented

2016-08-01 05:58:47 +02:00

Closed as duplicate of #43093

Campbell Barton closed this issue

2016-08-01 05:58:47 +02:00

Campbell Barton commented

2016-08-01 06:01:19 +02:00

Added subscriber: @ideasman42

Campbell Barton commented

2016-08-01 06:01:19 +02:00

Issues regarding alpha sorting in the view-port currently a known issue. (closing as duplicate).

Paolo Acampora commented

2016-08-01 09:21:02 +02:00

Thanks for your reply! :)

This isn't however a sorting issue: the problem here is with dupligroup ignoring the transparency flag altogether. Though somehow related, #43093 is about more transparent objects overlapping in the view, an issue yet to be addressed. This is about transparent dupli objects, even one transparent object only, not being added to the alpha pass, the way blender currently handles transparency.

It could be easily overlooked, if it wasn't that dupligroup are the reccomended way to reference characters in external blend file, and rather than a missing feature it's blender not being able to follow its own workflow.

Thanks for your reply! :) This isn't however a sorting issue: the problem here is with dupligroup ignoring the transparency flag altogether. Though somehow related, [#43093 ](https://developer.blender.org/T43093) is about more transparent objects overlapping in the view, an issue yet to be addressed. This is about transparent dupli objects, even one transparent object only, not being added to the alpha pass, the way blender currently handles transparency. It could be easily overlooked, if it wasn't that dupligroup are the reccomended way to reference characters in external blend file, and rather than a missing feature it's blender not being able to follow its own workflow.

Lucio Rossi commented

2016-08-02 13:02:08 +02:00

Added subscriber: @LucioRossi

Lucio Rossi commented

2016-08-02 13:02:23 +02:00

Removed subscriber: @LucioRossi

Ivan Cappiello commented

2016-08-02 13:02:58 +02:00

Added subscriber: @icappiello

Bastien Montagne commented

2017-07-03 20:35:52 +02:00

Added subscriber: @mont29

Bastien Montagne commented

2017-07-03 20:35:52 +02:00

If you want the patch to be considered, I strongly suggest to submit it as a differential instead… But not sure how likely it is to get accepted - and most certainly not for 2.79, this is way too late for that kind of changes imho.

If you want the patch to be considered, I strongly suggest to [submit it as a differential](https://developer.blender.org/differential/diff/create/) instead… But not sure how likely it is to get accepted - and most certainly not for 2.79, this is way too late for that kind of changes imho.

Paolo Acampora commented

2017-07-03 21:44:39 +02:00

Hello Bastien,

this is another case of a patch that was badly needed in production, so it was perfect to us, but might raise some concerns as a merge proposal, so it has been attached only to start a conversation.

Technically, it shouldn't be much of an overload: transparent objects are skipped when drawing dupligroups so that they can be rendered later. Of course this implies a further pass in which those objects are rendered and it is true that this might result in a (most probably very slight) overhead, but it should be benchmarked.

I can work on it to make it at least a good candidate for review, what has to be defined is if there is any interest in fixing the issue for the releases between 2.79 and 2.80

Hello Bastien, this is another case of a patch that was badly needed in production, so it was perfect to us, but might raise some concerns as a merge proposal, so it has been attached only to start a conversation. Technically, it shouldn't be much of an overload: transparent objects are skipped when drawing dupligroups so that they can be rendered later. Of course this implies a further pass in which those objects are rendered and it is true that this might result in a (most probably very slight) overhead, but it should be benchmarked. I can work on it to make it at least a good candidate for review, what has to be defined is if there is any interest in fixing the issue for the releases between 2.79 and 2.80

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translucent objects occlude other members in group instances #48983