[vtkusers] Drawing rubber band - SetRGBACharPixelData

[John Platt]

Hi,

I am trying to draw a black rubber band using

    pixels[...      ] = 0
    pixels[... + 1] = 0
    pixels[... + 2] = 0

and

    SetRGBACharPixelData( ..., pixels, 0 )

(taken from vtkInteractorStyleRubberBandPick). This works apart from the background, where no band is shown. If the transparency is set to 1

    pixels[... + 3] = 1

the band is drawn on the background but it is not erased when new pixel data is set, only on rendering.

SetPixelData( ..., pixels, 0 ) doesn't have the same problem but appears slower.

Any help would be much appreciated.

Thanks,

John.
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