[vtkusers] Adding two lightsources to a renderer

[Ken Martin]

I just tested this and it seems to work on master. This is the image I get.
Maybe this is an issue that has been fixed since 8.0 was cut?



[image: Inline image 1]

On Wed, Sep 6, 2017 at 2:17 PM, Oliver Natt <onatt at gmx.de> wrote:

> Dear vtkusers,
>
> I encountered a weird problem when using more than one positional light
> source in vtk. I am pretty sure that it worked with vtk 7.1 but it stopped
> working with vtk 8.0.0 and 8.0.1. An example in python is given below. The
> scene contains a plane which should be illuminated by two spot lights.
> However, only one spotlight is rendered. It seems that this is always the
> first spotlight that is added to the renderer. Is there any workaround for
> this problem?
>
> Many thanks
> Oliver
>
>
> import vtk
> # create a rendering window and rendererrenderer = vtk.vtkRenderer()
> render_window = vtk.vtkRenderWindow()
> render_window.AddRenderer(renderer)
> # create a renderwindowinteractoriren = vtk.vtkRenderWindowInteractor()
> iren.SetRenderWindow(render_window)
> # create a plane and add it to the rendererrectangle_source = vtk.vtkPlaneSource()
> rectangle_source.SetOrigin(-5.0, 0.0, 5.0)
> rectangle_source.SetPoint1(5.0, 0.0, 5.0)
> rectangle_source.SetPoint2(-5.0, 0.0, -5.0)
> rectangle_source.SetResolution(100, 100)
> mapper = vtk.vtkPolyDataMapper()
> mapper.SetInputConnection(rectangle_source.GetOutputPort())
> actor = vtk.vtkActor()
> actor.SetMapper(mapper)
> renderer.AddActor(actor)
> # set camera viewrenderer.ResetCamera()
> camera = renderer.GetActiveCamera()
> camera.Azimuth(40.0)
> camera.Elevation(30.0)
> # create a green lightlight_green = vtk.vtkLight()
> light_green.SetPositional(1)
> light_green.SetPosition(-4.0, 4.0, -1.0)
> light_green.SetColor(0.0, 1.0, 0.0)
> light_green.SetIntensity(0.5)
> # create a pink lighlight_pink = vtk.vtkLight()
> light_pink.SetPositional(1)
> light_pink.SetPosition(4.0, 5.0, 1.0)
> light_pink.SetColor(1.0, 0.0, 1.0)
> light_pink.SetIntensity(0.6)
> # add lights to the renderer## This is interesting in vtk 8.0.0 and 8.0.1:# Only the pink light spot is visible. If the two statements are swapped,# only the green light is visible. It seems that always only the first# light can be active.renderer.AddLight(light_pink)
> renderer.AddLight(light_green)
> # define a background for better visibilityrenderer.SetBackground(0.2, 0.2, 0.5)
> renderer.SetBackground2(0.4, 0.4, 1.0)
> renderer.SetGradientBackground(True)
> # enable interactoriren.Initialize()
> render_window.Render()
> iren.Start()
>
>
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-- 
Ken Martin PhD
Distinguished Engineer
Kitware Inc.
28 Corporate Drive
Clifton Park NY 12065

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