MantisBT - VTK
View Issue Details
IDProjectCategoryView StatusDate SubmittedLast Update
0003421VTK(No Category)public2006-06-19 19:342016-08-12 09:54
ReporterKen Moreland 
Assigned ToUtkarsh Ayachit 
PrioritynormalSeveritymajorReproducibilityalways
StatusclosedResolutionmoved 
PlatformOSOS Version
Product Version 
Target VersionFixed in Version 
Project
Type
Summary0003421: SNL: Mappers cannot share lookup tables and change opacity.
DescriptionWe ran into a very bizarre bug recently. We have an application that has several actors, and we want to be able to toggle the opacity if each one individually. We found that sometimes the opacity was usually not being restored to completely opaque correctly.

After much hunting, we discovered that it is because all the actors are sharing the same lookup table. What happens is that the mapper takes the opacity from the actor's property and then passes that to the alpha ivar of the lookup table. It also compares the property's opacity against the lookup table's alpha ivar to see if the colors need to be remapped.

Oops. If there are multiple actors, the lookup tables alpha ivar is not necessarily the same from the last time the render occurred. So if actor1 is opaque and actor2 just had its opacity changed from 0.5 to 1.0, then actor1 will set the lookup table's ivar to 1.0 and actor2 will assume that its opacity was always 1.0 and fail to update the colors.

The attached code demonstrates the bug.
Steps To Reproduce
Additional Information
TagsNo tags attached.
Relationships
Attached Filescxx opacity.cxx (2,716) 1969-12-31 19:00
https://www.vtk.org/Bug/file/5552/opacity.cxx
Issue History
Date ModifiedUsernameFieldChange
2008-02-06 10:42Jeff BaumesAssigned ToWill Schroeder => Utkarsh Ayachit
2008-02-06 10:43Jeff BaumesNote Added: 0010391
2011-06-16 13:11Zack GalbreathCategory => (No Category)
2016-08-12 09:54Kitware RobotNote Added: 0036876
2016-08-12 09:54Kitware RobotStatusexpired => closed
2016-08-12 09:54Kitware RobotResolutionopen => moved

Notes
(0005418)
Berk Geveci   
2006-10-16 13:43   
This is not targeted for paraview 2.6 release.
(0010391)
Jeff Baumes   
2008-02-06 10:43   
Is this still the case?
(0036876)
Kitware Robot   
2016-08-12 09:54   
Resolving issue as `moved`.

This issue tracker is no longer used. Further discussion of this issue may take place in the current VTK Issues page linked in the banner at the top of this page.