Part Loft Technical Details

[under construction]

Overview

This page explains the details of how the Loft surface is created. This also applies to Part:Sweep done along a straight path.

Stages of the Loft creation

To explain the process of loft, it is convenient to divide it into stages:

1. make number of segments in the profiles equal
2. establish correspondence between segments
3. make the loft surface

Making numbers of segment in profiles match

The process of slicing profile2 (white crescent-like shape) to create joints corresponding to vertices of profile1 (purple pentagon). The inserted joints are marked by yellow arrows.

The Loft needs the number of segments to match in order to create surfaces between corresponding segments. If the numbers of segments match in all profiles, this step is skipped. If at least one of the profiles as different number of segments, the following procedure is applied. The procedure is explained here for the case of only two profiles for simplicity.

1. the profiles are temporarily aligned so that they are coplanar and their centers of masses* match.
2. (see the picture) for every vertex in one profile, the second profile is sliced at the same polar angle (the polar center is the center of mass). If there is more than one slice possible or no slice possible at all (it can happen on very convex profiles), the Loft typically fails.
3. the same is done in the opposite direction.

The operation is extended to all profiles, to yield the equal number of segments. The total number of segments in each profile would be equal to the sum of all numbers of segments of all profiles (provided none of the vertices happen to be at the same polar angle).