@zipit work fine thanks a lot

@zipit
In this test, the modification works well, but the cycle button is not updated.
I added c4d.EventAdd(), but in this case it runs in a loop :)
Test2.c4d

@zipit Thanks. I test and keep you informed ;)

Test.c4d

I have a UserData "MyData" of type Button Cycle and i would like to modify its contents, in python node

Thanks @PluginStudent ;)

In a python node, is it possible to know how many inputs and outputs there are? and their name?

@Cairyn Thanks, all work fine for this module

@PluginStudent
Your link is about the creation of a material (and that I already know how to do), not a render parameter.

But I have tound the solution.

    shader = firstVP[c4d.VP_VRAYBRIDGE_ENVIRONMENT_BACKGROUNDTEX]
    if shader == None:
        shader = c4d.BaseList2D(c4d.Xbitmap)
        firstVP.InsertShader(shader)
        firstVP.GetDataInstance()[c4d.VP_VRAYBRIDGE_ENVIRONMENT_BACKGROUNDTEX] = shader
    shader[c4d.BITMAPSHADER_FILENAME] = "approaching_storm_4k.hdr"

Other question, how to remove it? I don't have found "DeleteShader" or "RemoveShader"