Blender Git Loki

Fixes T84928 : Lattice vertices at unexpected positions when changing lattice resolution from 1 to 3 or more.

Fix for T84928 .
Considering the changes , issue is resolved ( Ignoring readability issues) .

**Changes **:

- `Change in value assignment of fu/v/w :` Observing previous code , I noticed ,value assigned to them is equivalent to -0.5 ( i.e. co-ordinate of left most vertex of lattice size =1 where centre of lattice is origin ) .

- `Change in value assignment of du/v/w :` Margin ( distance ) between each division of surface along any axis is equivalent to **( (length of surface along axis ) / (no of division line - 1) )** . that's why is changed it to (default_size/unew -1) .

- ` New variable declared "default_size" :` As far as I gone through the code , I noticed values 1 < du ,fu < 1 , which indicates these values were calculated with respect to default lattice of size 1 .

- `removed pntsu/v/w != 1 check :` Following changes inside the if block worked properly for pntsu/v/w = 1 .

Reviewed By: lichtwerk, campbellbarton

Differential Revision: https://developer.blender.org/D10353