Confusion about the result of tutorial PlanarSectioning

[lavender-lee]

When I run the tutorial named "PlanarSectioning", I got the following console log:

write OFF file: F:/mcut/build/tutorials/OUT_conncomp0.off
write OFF file: F:/mcut/build/tutorials/OUT_conncomp1.off
write OFF file: F:/mcut/build/tutorials/OUT_conncomp2.off
write OFF file: F:/mcut/build/tutorials/OUT_conncomp3.off
write OFF file: F:/mcut/build/tutorials/OUT_conncomp4.off
write OFF file: F:/mcut/build/tutorials/OUT_conncomp5.off
write OFF file: F:/mcut/build/tutorials/OUT_conncomp6.off
write OFF file: F:/mcut/build/tutorials/OUT_conncomp7.off
write OFF file: F:/mcut/build/tutorials/OUT_conncomp8.off
write OFF file: F:/mcut/build/tutorials/OUT_conncomp9.off
write OFF file: F:/mcut/build/tutorials/OUT_conncomp10.off
write OFF file: F:/mcut/build/tutorials/OUT_conncomp11.off

It generates 11 polygon models, why?

In addition, I would like to know the meaning of normal and sectionOffset . How to define the a cutting plane? Thanks!

const McDouble normal[] = {0, 1, 1}; // can point in any direction
const McDouble sectionOffset = 0.45;

[TommyKaneko]

In addition, I would like to know the meaning of normal and sectionOffset . How to define the a cutting plane? Thanks!

A plane can be defined by:

• its normal (a 3D vector that is perpendicular to the plane)
• its offset from the origin - i.e the distance from the closest point of the plane to the origin

In an x, y, and z coordinate system, a plane equation can be defined as:
ax + by + cy - d = 0

... where [a,b,c] is the vector normal of the plane, and [d] is the offset

...

It generates 11 polygon models, why?

In the PlanarSectioning tutorial, you are likely retrieving ALL output from this line:
status = mcGetConnectedComponents(context, MC_CONNECTED_COMPONENT_TYPE_ALL, (McUint32)connectedComponents.size(), connectedComponents.data(), NULL);

...in most cases you would want to change the MC_CONNECTED_COMPONENT_TYPE_ALL flag to MC_CONNECTED_COMPONENT_TYPE_FRAGMENT. This returns the various fragments after the cut. However, there are still several components in that load of components! I have found that I only need the component that is at the end of the std::vector list of McConnectedComponents.

The Planar Section cut operation seems to move the geometry though, which is something else I am contending with....