Offset for retopo mode

Hi IStonia.
Do you think you could add an "offset" parameter for retopo mode?
What it would do is, instead of snapping right to reference surface, it would snap the retopo mesh to surface + the offset (along reference's normal vector).

Take a peek at this video:
https://youtu.be/PTQF_kBHEkU?t=5m15s
The author - Arrimus - uses the head as the retopo reference and sets the offset to some value. Now all geometry he creates in Max is offset from the reference mesh by the value he has entered in the parameter. (Though from what I see it's a little bit broken in Max...)
This would be very handy!

Does this setting provide enough offset ?

Thanks but no. That's Z offset. I need real physical offset.

IStonia, would you implement this when you have some time?

Here's how I picture this feature:
The physical offset should work for all newly created components only. So for example when you set it to 1 unit and place several faces, they would be spaced by 1 unit from the reference surface. Then, if you change the offset to 2 units, all newly created components will be 2 units away from the reference mesh, but components that already have been created will still be at 1 unit away. Unless you start moving them around of course, in which case the would be snapped to current offset.

Try this
http://www.digitalfossils.com/Download/NVil-Dec-15-15.rar

The offset value is used in a core function which is used by some operations which is not retopo related. So disable it if you don't use it.

The offset command is an incredibly useful feature, thanks for implementing it.

When extruding lower edge, the polys ended up inside the sphere instead of offset 20 units.

I can't seem to find a way to drag them out of the sphere.

When extruding polys on the upper surface of the sphere they work fine.

Some operations use viewport camera direction others vertex normals which will have unpredictable result.
Now if offset is enabled, they will all use viewport camera direction. See if it's better.
http://www.digitalfossils.com/Download/NVil-Dec-16-15.rar

Thats working nicely now Istonia, thanks !

I think generally as you retopo objects you tend to rotate the camera to a kind of top down view so the viewport camera direction is the way to go.

Thank you very much IStonia for adding this feature.

I find the Dec-15-15 version better that the one from 16th December, because the latter enforces viewport camera direction snapping, while with Dec-15-15 I can use "Vertex Normal for Retopo Snap on Transform" for offset snapping whenever it's necessary (and I use it most of the time). All snapping errors that Kevjon mentioned can be quickly fixed by temporarily disabling this kind of snapping.

What do you think of restoring the freedom of choice for choosing offset snapping method, and moving the "Vertex Normal for Retopo Snap on Transform" from Edit->Options menu to Retopo Reference List?

I think generally as you retopo objects you tend to rotate the camera to a kind of top down view so the viewport camera direction is the way to go.

Not always. Many times when retopologizing in NVil or 3D-Coat I perform tweaks of loops that go around the object. If camera direction snapping is enabled, then any operation performed on this kind of selection will break the geometry because vertices instead of snapping to the closest surface along normal will try to snap to closest surface that's facing viewport's camera.
I almost never use viewport camera direction snapping.

http://www.digitalfossils.com/Download/NVil-Dec-20-15.rar

Option "Enforce camera direction for offset" is added.