Zcombine wrong alpha clipping since 2.67 #35586

New Issue

Paul Andruchiewicz · 2013-05-31T20:06:32+02:00

2013-05-31 20:06:32 +02:00

%%%--- Operating System, Graphics card ---
Windows 7 64bit, Nvidia 550ti

- Blender version with error, and version that worked ---

since 2.67 it works wrong/different. in 2.66a it has worked well (for me)

- Short description of error ---

You can look in my blendfile. There are two renderlayers and they are put together with z combine node. When "use alpha" is activated the grid is nearly invisible in blender 2.67. In blender 2.66 it worked different/better. It seems if the clipping of the alpha channel changed but why? Its not the reason of different user preferences and i see no way to control it.

- Steps for others to reproduce the error (preferably based on attached .blend file) ---

%%%

%%%--- Operating System, Graphics card --- Windows 7 64bit, Nvidia 550ti - Blender version with error, and version that worked --- since 2.67 it works wrong/different. in 2.66a it has worked well (for me) - Short description of error --- You can look in my blendfile. There are two renderlayers and they are put together with z combine node. When "use alpha" is activated the grid is nearly invisible in blender 2.67. In blender 2.66 it worked different/better. It seems if the clipping of the alpha channel changed but why? Its not the reason of different user preferences and i see no way to control it. - Steps for others to reproduce the error (preferably based on attached .blend file) --- %%%

Paul Andruchiewicz commented

2013-05-31 20:06:32 +02:00

Changed status to: 'Open'

Ton Roosendaal commented

2013-06-01 14:39:54 +02:00

%%%The render layers all have alpha 1, so the "use alpha" in zcombine should simply have no effect.
Disable it for now to get it render fine.

Will ask Jeroen if he can find why this fails now.%%%

%%%The render layers all have alpha 1, so the "use alpha" in zcombine should simply have no effect. Disable it for now to get it render fine. Will ask Jeroen if he can find why this fails now.%%%

Paul Andruchiewicz commented

2013-06-01 16:59:24 +02:00

%%%when i disable alpha, i get white edges. %%%

Monique Dewanchand commented

2013-06-08 22:36:18 +02:00

%%%Seems to be related to cycles renders. Blender internal works fine. Cycles renders with narrow edges creates artifacts. Not sure why but could be uninitialized memory.
Z buffer seems to be correct.%%%

%%%Seems to be related to cycles renders. Blender internal works fine. Cycles renders with narrow edges creates artifacts. Not sure why but could be uninitialized memory. Z buffer seems to be correct.%%%

Jeroen Bakker commented

2013-06-30 15:38:23 +02:00

%%%According to Brecht, cycles has thinnier Z-Edges than Blender internal. So basically it is not an issue of the compositor, but on the input data.
%%%

%%%According to Brecht, cycles has thinnier Z-Edges than Blender internal. So basically it is not an issue of the compositor, but on the input data. %%%

Paul Andruchiewicz commented

2013-06-30 22:31:18 +02:00

%%%i remind : 2.66a it worked well%%%

Thomas Dinges commented

2013-07-07 11:53:47 +02:00

%%%If this worked in 2.66, then this is a regression and should be fixed.

Brecht, could you check if this is really a problem of Cycles? %%%

%%%If this worked in 2.66, then this is a regression and should be fixed. Brecht, could you check if this is really a problem of Cycles? %%%

Brecht Van Lommel commented

2013-07-07 12:38:17 +02:00

%%%I discussed this with Jeroen on IRC. The problem is that the "antialiasing" Z Combine does is designed to work with Blender Internal Z passes but doesn't work well with Cycles. I wouldn't say either is wrong and personally think the Cycles Z pass make more sense (and it kind of shows by it not needing this antialiasing step as much).

It's a regression compared to 2.66 because it was actually broken for Blender Internal there, now that's fixed but it breaks behavior for Cycles again and works like the old compositor. Not sure what the best solution is, maybe this node should have an option to control the antialiasing. That's a bit annoying but I also don't like to change the Z pass of either Cycles or Blender Internal.%%%

%%%I discussed this with Jeroen on IRC. The problem is that the "antialiasing" Z Combine does is designed to work with Blender Internal Z passes but doesn't work well with Cycles. I wouldn't say either is wrong and personally think the Cycles Z pass make more sense (and it kind of shows by it not needing this antialiasing step as much). It's a regression compared to 2.66 because it was actually broken for Blender Internal there, now that's fixed but it breaks behavior for Cycles again and works like the old compositor. Not sure what the best solution is, maybe this node should have an option to control the antialiasing. That's a bit annoying but I also don't like to change the Z pass of either Cycles or Blender Internal.%%%

Brecht Van Lommel commented

2013-07-12 22:16:46 +02:00

%%%Add an option to the node now, you can disable it to get the result from the 2.64 to 2.66 releases.%%%

Brecht Van Lommel commented

2013-07-12 22:16:46 +02:00

Changed status from 'Open' to: 'Resolved'

Brecht Van Lommel closed this issue

2013-07-12 22:16:46 +02:00

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Zcombine wrong alpha clipping since 2.67 #35586