Change of behaviour of Tessellate processing tool

[Dan-Eli]

Feature description.

Starting from QGIS 3.10 there is a change in behaviour in the way the Tessellate processing tool is triangulating polygons.

The following figure is an example of tesssellation (triangulation) with QGIS version prior to 3.10 (3.8 and below)

The following figure is an example of tessellation with QGIS version 3.10 and over

While both version are valid polygon triangulation, the first one is more suited for shape analysis like extracting the Chordal axis (center line) of long any narrow polygons. Is the newer approach exploiting the probably easier and faster approach of fan triangulation, I don't know?

If the newer approach to tesselation is wanted/needed, could you please add a switch enabling to reproduce the older triangulation approach, for the ones who need that kind of triangulation. If it is not needed or wanted, bring back the old triangulation approach.

As you can see with the preceding description I do not know if I should tag this issue as bug or improvement... I will let you choose the right one

Additional context

The file included GeoPackage contains five layers. the layer named Polygons_v_3_12 contains the input polygons for the Tessellation. The other layers are the output of the tessellation for the following QGIS version: 3.4, 3.6, 3.8, 3.10 (3.12 is not included but it is the same has 3.10). A last observation, the new behaviour seems more to happen for long and narrow polygons that are either almost horizontal or almost vertical.

data_tessellate.zip