3D View GLSL irregularity with z-transparency based on selected(active) object #31158

New Issue

Brian Wipf · 2012-04-28T15:29:29+02:00

Brian Wipf commented

2012-04-28 15:29:29 +02:00

%%%I have observed a change in the way the 3D Viewport displays Z-transparent materials under GLSL display with "texture" viewport shading. Some objects that could previously be seen through a transparent object now disappear (clipped or masked out) if the transparent object is not the currently selected object.

There is no category for 3D viewport so I am calling this an "Interface" category issue, for lack of a more apparent category to have chosen.

Since I do not know if this counts as a showstopper, I was hesitant to report it. It is apparently a new 3D-Viewport 3d buffering issue with Z-transparency that started happening with r2.61, that is to say r2.60 was still fine as far as I can determine.

In the simplest case, create a lot of objects with normal materials, and a single plane with z-transparency. View in GLSL with texture viewport shading. As long as the transparent plane is active and selected (highlighted), all objects can be seen through the transparent pane. When any other objects, or no objects at all, are selected, some objects get "masked" out instead of displayed. The grid floor can always be seen through the transparent object. For convenience, I rotate the transparent plane 90 degrees to the vertical in my tests, ie the plane is a window, not a floor.

I have attached a file with the transparent object selected. Objects in the 3D viewport can be seen behind it in textured GLSL mode. To test, select any other object... a camera, another plane, a lamp.

Windows 64 bit, Blender 2.63, also confirmed on 2.62 and 2.61, no special graphics cards. Not a problem with 2.60 or 2.5 versions.%%%

%%%I have observed a change in the way the 3D Viewport displays Z-transparent materials under GLSL display with "texture" viewport shading. Some objects that could previously be seen through a transparent object now disappear (clipped or masked out) if the transparent object is not the currently selected object. There is no category for 3D viewport so I am calling this an "Interface" category issue, for lack of a more apparent category to have chosen. Since I do not know if this counts as a showstopper, I was hesitant to report it. It is apparently a new 3D-Viewport 3d buffering issue with Z-transparency that started happening with r2.61, that is to say r2.60 was still fine as far as I can determine. In the simplest case, create a lot of objects with normal materials, and a single plane with z-transparency. View in GLSL with texture viewport shading. As long as the transparent plane is active and selected (highlighted), all objects can be seen through the transparent pane. When any other objects, or no objects at all, are selected, some objects get "masked" out instead of displayed. The grid floor can always be seen through the transparent object. For convenience, I rotate the transparent plane 90 degrees to the vertical in my tests, ie the plane is a window, not a floor. I have attached a file with the transparent object selected. Objects in the 3D viewport can be seen behind it in textured GLSL mode. To test, select any other object... a camera, another plane, a lamp. Windows 64 bit, Blender 2.63, also confirmed on 2.62 and 2.61, no special graphics cards. Not a problem with 2.60 or 2.5 versions.%%%

Brian Wipf commented

2012-04-28 15:29:29 +02:00

Changed status to: 'Open'

Brecht Van Lommel commented

2012-05-01 11:47:52 +02:00

%%%Basically drawing transparent surfaces is not natively support with OpenGL, and we don't do any advanced alpha sorting in the viewport like in game engines (where transparent surfaces are usually avoided). There are however two things that affect drawing order:

If Transparent is enabled in the Object properties Display panel, the object will be draw after others to ensure it draws on top.
If the Object is selected, it will be draw last, to ensure it is at least visible for editing even if it would be otherwise obscured incorrectly.

Before 2.61 having a GLSL material with alpha would automatically enabled "Transparent" on the object, however this was causing issues in some cases, now instead it needs to be set manually.%%%

%%%Basically drawing transparent surfaces is not natively support with OpenGL, and we don't do any advanced alpha sorting in the viewport like in game engines (where transparent surfaces are usually avoided). There are however two things that affect drawing order: * If Transparent is enabled in the Object properties Display panel, the object will be draw after others to ensure it draws on top. * If the Object is selected, it will be draw last, to ensure it is at least visible for editing even if it would be otherwise obscured incorrectly. Before 2.61 having a GLSL material with alpha would automatically enabled "Transparent" on the object, however this was causing issues in some cases, now instead it needs to be set manually.%%%

Brecht Van Lommel commented

2012-05-01 11:47:52 +02:00

Changed status from 'Open' to: 'Archived'

Brecht Van Lommel closed this issue

2012-05-01 11:47:52 +02:00

Brian Wipf commented

2012-05-01 14:45:27 +02:00

%%%I thought it might have been something like that. If it must be, it must be.

My first rejected bug! At least this gives me the push to learn the game engine instead of relying on the 3D view for walkthroughs, and that's a good thing.%%%

%%%I thought it might have been something like that. If it must be, it must be. My first rejected bug! At least this gives me the push to learn the game engine instead of relying on the 3D view for walkthroughs, and that's a good thing.%%%

Brecht Van Lommel commented

2012-05-01 14:55:13 +02:00

%%%You should be able to get it to behave the same as before though, enabling the Transparent option manually.%%%

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3D View GLSL irregularity with z-transparency based on selected(active) object #31158