[vtkusers] vtkGPUVolumeRayCastMapper: Updateing ImageData after first Rendering?

[Willy]

Thanks for your reply, but i think i described my problem not detailed
enough.

I don't use vtkRenderWindowInteractor. I have a .NET project with .Net
PictureBox in it and a C++ Project witch encapsulates all the vtk stuff. To
show the rendered vtk image in my picturebox i set my vtkRenderWindow to
OffScreenRenderingOn() and use the following method to Convert vtkImageData
to a .NET Bitmap:

void VolumeRenderer::Render3DImage(int width, int height, Bitmap^% image)
{
    _RenderWindow->SetSize(width, height);
    _CurrentRenderer->ResetCameraClippingRange();
    vtkRenderLargeImage* imageFilter = vtkRenderLargeImage::New();
    imageFilter->SetInput(_CurrentRenderer);
    imageFilter->SetMagnification(1);
    imageFilter->Update();
    ConvertRGBVTKImageToBitmap(imageFilter->GetOutput(), image);
    imageFilter->Delete();
}

Each time the user moves the mouse, changes the color, ... i change the
Position/Rotation of the camera or the vtkColorTransferFunction or wathever.
And after that i recall Render3DImage to get the new Picture which i show in
my PictureBox. After the very first call of Render3DImage the rendered image
does not change anymore if i change the data in my vtkImageData (using
memcpy). i guess that the very first call of Render3DImage copies my
cpu-Memory (where vtkImageData is) to the gpu. If a change the vtkImageData
after that it does not affect the gpu-memory.
Am i rigth? what can i do?



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