Weird behavior seting color to vtkPolyData

Question

I'm trying to assign custom colours to cells in VTK. If I render my model without any colour assignment, it looks like this:

Inspired by

color = vtk.vtkUnsignedCharArray() 
color.SetName("Colors") 
color.SetNumberOfComponents(3) 
color.SetNumberOfTuples( surface.GetOutput().GetNumberOfCells() )
    
for i in range(surface.GetOutput().GetNumberOfCells()):
    color_tup=[0,0,255]
    color.SetTuple(i, color_tup)

Answer 1

I found out that this fix my problem:

mapper = vtk.vtkPolyDataMapper()
mapper.SetInputConnection(surface.GetOutputPort())
mapper.SetColorModeToDirectScalars()
mapper.SetScalarModeToUseCellData()