When I try to display a scene containing a transparent object (50% transparency) and a textured opaque object, the transparent object becomes paler. If the textured object is hidden, the transparent object again receives the expected transparency.
I map the texture to the object with vtkTextureMapToSphere. Please note that boundsin the code below is the bounding box of the object _polydatato which I apply the texture.
vtkTextureMapToSphere textureMapper = vtkTextureMapToSphere.New();
textureMapper.SetInput(_polydata);
textureMapper.SetCenter(bounds.center[0], bounds.center[1], bounds.center[2]);
textureMapper.PreventSeamOn();
vtkTransformTextureCoords transformMap = vtkTransformTextureCoords.New();
double factorEnlarge = 4;
double scale = bounds.dimensions.Sum() / bounds.dimensions.Length / factorEnlarge;
transformMap.SetInputConnection(textureMapper.GetOutputPort());
transformMap.SetScale(scale, scale, scale);
vtkPolyDataMapper mapper = vtkPolyDataMapper.New();
mapper.SetInputConnection(transformMap.GetOutputPort());
vtkActor actor = vtkActor.New();
actor.SetTexture(texture);
actor.GetProperty().SetColor((double)color.R / 255, (double)color.G / 255, (double)color.B / 255);
actor.GetProperty().SetOpacity(alpha);
actor.SetMapper(mapper);
actor.GetProperty().SetInterpolationToPhong();
renderer.AddActor(actor);
EDIT
After disabling the PreventSeam parameter vtkTextureMapToSphere, the color difference disappeared. However, there is still a noticeable difference in shading, wherever you look at more than two mesh surfaces (for example, where there are cavities in the mesh).
