How to get all points that make up a certain shape in vtk

Question

I am working in my graduation project and one of the tasks I am required to draw a 3D shape(for example an ellipsoid using vtkSampleFunction), this represents the heart for example. I need to change the color of certain areas in that shape and make color gradients using 2 colors for example. How can this be achieved? All I could find is that cant be done without having polydata(points) and I dont know how to access specific points on the outline of my shape. Any help would be appreciated

I tried millions of ways to access points on the outline of my shape but I cant find anyway to do it. I am new to VTK so please try to simply any answer. Thank You

Answer 1

If you are looking for a way to extract all the points inside a surface, you can use the vtkSelectEnclosedPoints method. For example, if you want to find out which all points in pointsPolydata lie inside the surface surfacePolydata , you can use the below example.

select = vtkSelectEnclosedPoints()
select.CheckSurfaceOn ()
select.SetTolerance(0.001)
select.SetInputData(pointsPolydata)
select.SetSurfaceData(surfacePolydata)
select.Update()
outPut=select.GetOutput()

The outPut polydata will have an array named "SelectedPoints" , with 0 for point outside the surface and 1 for points inside the surface.

For more details, refer vtkSelectEnclosedPoints