Create truncated Cone

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1

Hello,

I want to display a truncated code like the following
cone

Any hint would be appreciated.
Thanks

2

You can create any rotationally symmetric shape from a polyline using vtkRotationalExtrusionFilter.

3

This example shows how to use the vtkRotationalExtrusionFilter to extrude a line segment, so is directly applicable for generating this shape:

https://vtk.org/gitweb?p=VTK.git;a=blob;f=Filters/Modeling/Testing/Cxx/TestRotationalExtrusion.cxx

1 Like
4

Also look at: CappedSphere. You should be able to easily modify the function GetLine to do what you want.

1 Like
5

I made a vtkTruncatedConeSource with a simple modification of vtkCylinderSource. Just add some getters and setters for Radius1 and Radius2 instead of Radius. And replace the usage of Radius in the top and bot values in vtkCylinderSource.cxx with Radius1 and Radius2 appropriately. Iā€™d post the whole code but vtkCylinderSource.h/.cxx is a lot.

6

That should work, although creating a line and rotating it would have been simpler.:smiley:

7

Here is a quick example creating a line to rotate to make a truncated cone that you can drop into CappedSphere (the C++ version is easy to create from this, it is left as an exercise for the reader).

def get_line1(height, radius1, radius2, step, uncapped):
    """
    Get the points for a line.

     The parametric equations for the line are:
       x = x1 + (x2 - x1) / t
       z = z1 + (z2 - z1) / t
       0 <= t <= 1

    Conditions:
      height > 0
      radius2 < radius1
      step > 0


    :param height: Height of the cone.
    :param radius1: Radius of the base of the cone.
    :param radius2: Radius of the top of the truncated cone.
    :param step: The number of points in each line.
    :param uncapped: True if uncapped.
    :return: A vector of points.
    """
    pts = list()

    t = 0
    x02 = radius2
    z02 = height / 2
    if not uncapped:
        # Create the cap for radius2
        while t < 1:
            if t != 0:
                x = x02 * t
                z = z02
            else:
                x = 0
                z = z02
            pt = (x, 0, z)
            pts.append(pt)
            t += 1.0 / step
    # The sloped line for the cone
    t = 0
    x21 = radius1 - radius2
    z21 = height / 2
    while t <= 1:
        if t != 0:
            x = radius2 + x21 * t
            z = z21 - height * t
        else:
            x = radius2
            z = z21
        pt = (x, 0, z)
        pts.append(pt)
        t += 1.0 / step
    t = 0
    x10 = radius1
    z10 = -height / 2
    if not uncapped:
        # Create the cap for radius1
        while t < 1:
            if t != 0:
                x = radius1 - x10 * t
                z = z10
            else:
                x = radius1
                z = z10
            pt = (x, 0, z)
            pts.append(pt)
            t += 1.0 / step
    return pts