Opened 17 years ago

Closed 15 years ago

Last modified 14 years ago

#403 closed defect (worksforme)

Rendering extremely slow with vector transparency

Reported by: gsherman Owned by: wonder
Priority: critical: causes crash or data corruption Milestone:
Component: MapCanvas Version: Trunk
Keywords: Cc:
Must Fix for Release: Yes Platform: All
Platform Version: Awaiting user input: no


Rendering with vector transparency set is intolerably slow if antialiasing is turned off. On a new install, we should set AA on by default.

If someone can confirm this, we should issue a warning when setting transparency if AA is off.

Change History (8)

comment:1 by mhugent, 17 years ago


This does not happen on my system (Kubuntu 6.10, Qt-4.2.1). Performance is ok for me with transparency and with/without AA.

cheers, Marco

comment:2 by g_j_m, 17 years ago

Works fine for me with Qt-4.2.1 under Linux with most polygons. With very complicated polygons or .shp files with large numbers of polygons I do see a small difference, but nothing that is significantly slower.

comment:3 by gsherman, 17 years ago

Resolution: invalid
Status: newclosed

Perhaps this is an issue with my (and others) X11 configuration.

I'll close this issue.

comment:4 by neteler, 16 years ago

Awaiting user input: unset
Resolution: invalid
Status: closedreopened

I am using Madriva2007 with QT4.2.1 and rendering is indeed extremely slow with vector transparency. Using SVN HEAD.

So I suggest to add a warning about this in case AA is disabled. I take liberty to reopen. In the German translation it is rather impossible to understand what checkboxes should be activated to avoid this slowliness.


comment:5 by pcavallini, 16 years ago

Milestone: Version 0.8Version 0.8.1

comment:6 by timlinux, 16 years ago

Milestone: Version 0.8.1Version 0.8.2

Im testing with qt4.3 and I cant replicate. In many cases turning on anti-aliasing will actually slow down rendering so I think its going to be very confusing to put up a message saying 'turn on AA to speed up rendering with transparnecy, but AA will slow down rendering.'. Im going to forward this bug to 0.8.2, but I wonder if the preblem is resolved with qt4.3 in which case we should consider recommending this version of qt4.3.


comment:7 by timlinux, 15 years ago

Resolution: worksforme
Status: reopenedclosed

Closed - works for me under Qt 4.3 & Qt4.4. Please reopen if problem persists under a current version of Qt4. Suggestions to improve wording of options for clarity in German would be welcome.



comment:8 by (none), 14 years ago

Milestone: Version 1.0.0

Milestone Version 1.0.0 deleted

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