Hi Nigel, some info on the other one:
> Project to plane in ortho views
So this option is to make drawing in the ortho views produce planar objects for things like lines, polylines, and freeform curves, even when you grab a snap point for points after the very first picked point. It does this by projecting that snap point to a plane going through the first picked point. But this only happens when you are using the mouse inside of an ortho viewport.
The basic idea is that it makes ortho viewports generate planar objects (parallel to the same plane as the ortho view) when you draw lines and curves in them.
Here's a visual - here again I have 2 lines that are on different z levels, here you see the Top and 3D views of them:
So now I'm going to draw in a line, with the first point of the line snapped on to here:
Then when snapping the 2nd point of the line to the other endpoint towards the right (while inside the Top view), if "Project to plane in ortho views" is enabled, it will produce this result:
So note there that the end object snap was projected down to a plane going through the first point. The white line that you can see in the 3D view indicates the projection.
That makes the line that is being drawn to be parallel to the Top view. It doesn't project the very first point though, the first point can be freely placed which basically sets the level of the plane that will be used.
If you turn off "Project to plane in ortho views", you will get this result instead:
So note there that no projection happened to the 2nd point, so the resulting line is not parallel to any Top/Front/Right view, it's angled in 3D, but also the line in this case physically touches each snap point.
The way this is intended to be used is that with this option enabled you don't have to switch options on or off to get planar drawing, instead of switching options you make planar things by drawing in an ortho view, and if you need direct non-projected snaps you click those snap points in the 3D view which does not have projection applied to it.
I included an option to disable it though just in case you want to have thing drawn in to direct points without any projection in all views.
It is possible to make a similar kind of planar projected drawing happen in the 3D view as well by setting up a script on a keyboard shortcut, let me know if you want me to dig that up.
- Michael