Some of the features of the PolyMesh editor can be very frustrating when you don't know how to put them to work. Sure, you should read the manual, but time is missing, as always. Plus there is this odd behavior that you feel is entirely wrong. Well, just read this page and you'll know enough of the trickiest of the polymesh traps to edit a mesh without frustration.

Mesh Tension

The mesh tension is a frequent source of bewilderment from new users. « I move/scale/rotate the selection and unselected vertices move along the selected ones! ». In such a case, check the mesh tension. This parameter is the distance over which a selected vertex will take a neighbor vertex with it when moving. This distance is measured in terms of number of edges. A value of 0 means that vertices move independantly of unselected ones, whereas increasing values spreads out the influence of the selection over the rest the mesh.

Live Mirror

« I tried to setup a live mirror and it doesn't work ! » is also a common cry of despair heard from users. The live mirror feature is strict and doesn't allow for loose setup. However, remembering this sentence will save you a lot of trouble « Mirror occurs along faces the vertices of which exactly lie on the mirror plane ». Let's review the terms of this sentence so as to fully understand what they mean. « Mirror occurs along faces ». Have a look at the picture below. The cube is mirrored because one of its face lies on the mirror plane. Now look at the second cube which is the same cube for which the face lying on the mirror plane has been removed. Though the 4 edges delimiting the boundary thus created all lie on the mirror plane, no mirroring effect is applied.

Then there is the second part of the sentence : « the vertices of which exactly lie on the mirror plane ». Where are those mirror planes ? Well they are the ones that run along the local coordinates axis. Look at the figure below which displays the three mirror planes along the axis system. The blue plane, perpendicular to the X direction, is called YZ. The green plane, perpendicular to the Y direction, is called XZ. Finally the red plane is called XY. A good way to remember which plane to use as mirror is that if you put one coordinate (say X) to zero using the Edit Points command from the vertex menu, then the mirror to use is the one that doesn't have X in his name. So, to setup a mirror whithout pain, run the following porcedure :

1) Move the mesh so that the vertices of faces to put on the mirror approximately lie on this mirror.

2) Select the faces along which you want the mirror to occur.

2) Edit points and set the relevant coordinate to zero.

3) Activate the live mirror feature selecting the mirror that doesn't have the coordinate you set to zero in its name.

« Hey, I did exactly as advised above and yet my mesh is not mirrored! ». This happens when the coordinate system used in the mesh editing window is the scene coordinate system and not the local coordinate system. This is very important : the mirrors lie on local the axis system. If you edit the mesh using global coordinate system, then setting one coordinate to zero doesn't bring the faces on the mirrors.

Mirroring occurs on faces aligned on mirror planes

The 3 mirrors available for live mirroring : blue plane YZ, green plane XZ and red plane XY.

Edge Loop Collapse

Hey, I collapsed an edge loop and the editor is now blank and my CPU is still working ?!

Remember: edge collapse brings together the two vertices at each end of an edge. So collapsing an edge loop actually replaces the loop by... yes, a single vertex. This results in an improper mesh, except if the edge loop exactly delimits a face, which is a very rare case.

If you want to remove an edge loop, select the edge strip between two loops you want to reduce to one and collapse it.

Comments (1)

Only registered users can leave comments.
Please login or register.

Powered by AkoComment Tweaked Special Edition v.1.4