MantisBT - VTK
This results in vtkRenderWindow::Render() being called from the middle of vtkOpenGLRenderWindow::OpenGLInit() with some of the settings which are set in this function still disabled, most notably GL_NORMALIZE. This in turn results in wrong rendering results during the first render after program start, which are very noticeable in some circumstances. See the attached image, on the left what it should look like, and on the right what it actually looks like.
The issue only happens when vtkRenderWindowInteractor::Start() (or Initialize()) is called, and only on the first render pass, thus on any next render pass (such as after any interaction) the image is as it should be. When vtkRenderWindow::Render() is called the issue does not happen, because vtkRenderWindow::Render sets NeverRendered to 0 before any initialization, thus before OpenGLInit() gets called.
The extension manager should probably not call Render at all, since the manager works just as well when the RenderWindow has not yet actually ever rendered anything in spite of the NeverRendered ivar being set to 0. This happens when vtkRenderWindow::Render() is called - the ivar is 0 but no rendering has yet happened when the manager checks this ivar when it is created in OpenGLInit)).
example.png (2,434) 2008-02-26 09:14https://www.vtk.org/Bug/file/6327/example.png
