# About draw a cylindeical ring , use boolean operation
**URL:** https://discourse.vtk.org/t/about-draw-a-cylindeical-ring-use-boolean-operation/14792
**Category:** Support
**Tags:** code
**Created:** [October 31, 2024, 7:29am UTC](https://discourse.vtk.org/t/about-draw-a-cylindeical-ring-use-boolean-operation/14792 "2024-10-31T07:29:48Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@nanoahSR](https://discourse.vtk.org/u/nanoahSR)
#### Post date: [October 31, 2024, 7:29am UTC](https://discourse.vtk.org/t/about-draw-a-cylindeical-ring-use-boolean-operation/14792/1 "2024-10-31T07:29:48Z")
I want to use boolean operations to draw a cylinder ring:
1. create two cylinder,
2. use vtkTrianglefilters,
3. and then Boolean operations,
but why is that?
code:
```C++
// Function to create a cylinder
vtkSmartPointer CreateCylinder(double radius, double height)
{
auto cylinderSource = vtkSmartPointer::New();
cylinderSource->SetCenter(0, 0, 0);
cylinderSource->SetRadius(radius);
cylinderSource->SetHeight(height);
cylinderSource->SetResolution(100); // Controls smoothness of the circle
cylinderSource->Update();
auto triangFilter = vtkSmartPointer::New();
triangFilter->SetInputData(cylinderSource->GetOutput());
triangFilter->Update();
return triangFilter->GetOutput();
}
int main(int, char*[])
{
// Outer cylinder (the larger one)
auto outerCylinder = CreateCylinder(2, 1);
// Inner cylinder (the smaller one to subtract)
auto innerCylinder = CreateCylinder(1, 1);
// Boolean filter to subtract inner cylinder from the outer one
auto booleanFilter = vtkSmartPointer::New();
booleanFilter->SetOperationToUnion();
booleanFilter->SetInputData(0, outerCylinder);
booleanFilter->SetInputData(1, innerCylinder);
booleanFilter->Update();
// Mapper and actor for the resulting ring
auto mapper = vtkSmartPointer::New();
mapper->SetInputData(booleanFilter->GetOutput());
mapper->ScalarVisibilityOff();
auto actor = vtkSmartPointer::New();
actor->SetMapper(mapper);
actor->GetProperty()->EdgeVisibilityOn();
....
}
```
Refer to： [What’s the problem? Somebody help me - Support - VTK](https://discourse.vtk.org/t/what-s-the-problem-somebody-help-me/1890)
---
### Author:  [@Jens\_Munk\_Hansen](https://discourse.vtk.org/u/Jens_Munk_Hansen)
#### Post date: [November 2, 2024, 8:52pm UTC](https://discourse.vtk.org/t/about-draw-a-cylindeical-ring-use-boolean-operation/14792/2 "2024-11-02T20:52:41Z")
Perhaps, you could use implicit functions instead, two vtkCylinder and two vtkPlane. Here I used two vtkCylinder and 4 vtkSphere
