Custom Axes and Snapping along Global Axes?

Support Modeling
#1

Is there a possible way to snap along global axis when using custom transform axes? For example, open Blender, delete default cube, and add 2 planes. Don’t move any, just rotate one of the planes 45 degrees along the Y-axis. Now, with the face selected in Edit Mode, Ctrl+Alt+Shift to create an orientation based on the face. Select the top two vertices of the plane, which are above the level plane. Slide them along the face using the custom axis. I want to position these so they are vertically in line with the level plane, while keeping the original exact 45-degree rotation.

In reality, if I was presented with a scenario as above, I’d just subdivide. But this is just an example, I’ll be applying this to much more complex examples.

#2

Well in your case, moving by a unit of 1 along your custom transform orientation will put you right at the intersection.


You could also use tinyCAD XALL (requires plugin) to merge the edges at their intersection.
But it sounds like you want an approach that doesn’t involve merging geometry?

#3

Edit Mode, Ctrl+Alt+Shift to create an orientation based on the face.

That should be Ctrl+Alt+Space.

Blender has Snapping function. Its that magnet icon on the 3D menu bar. The tool some time fails to work for me. So play with it.

#4

I’m having the same problem as the OP, and the above replies are insufficient. The TinyCAD tools only work for coplanar edges. They would work in the OP’s simple example, but not more complex situations. The best solution I’ve come up with is to to a boolean intersection of the two objects. This will create vertices in the appropriate locations to snap to. But my situation is a bit different from the OP’s. I’m trying to snap an element to another element of the same object in the way the OP described. So my solution requires separating both elements into individual objects, doing the boolean operation, then rejoining them with the original object. And in either case, there should be a more straight-forward solution.

I’m going to make a follow-up post demonstrating a more nuanced situation and see if anyone can offer a better solution.

#5

Seeing as this is not possible without the use of other external scripts, this brings up another question. I’ve noticed that Knife Project tool is a tad inaccurate in the placement of the cut vertices. This works great for faces that are exactly lined up on the X, Y, or Z axis, but not so great for faces at an angle. The vertices are slightly off from retaining perfect planar position of the original face. This is occasionally solved by creating custom transform axis to the original face, then scale 0 while selecting original face vertices, but this slightly moves the cut vertices from original cut position.

Does boolean cut have the same issues?

#6

Snapping has limitation in that it can’t snap on an intersection of two angles based on the transform orientation and geometry. Those would have to be in 90 degree angle from each other to be accurate.

One workaround is to snap the view to appropriate mesh element and use face snapping to project selected vertices on the intersection while facing it at a correct angle

screen.png1280×948 124 KB

Boolean modifier doesn’t do well with non-manifold geometry. Could use edit mode tools like intersect, knife project, knife, bisect. Here are the first two

#7

This was the first thing I tried when I tried to solve this problem, but it never worked for me. The snap tool always snaps to the transform orientation axis, ignoring the view angle. Unless I’m misunderstanding you…

Boolean modifier doesn’t do well with non-manifold geometry. Could use edit mode tools like intersect, knife project, knife, bisect. Here are the first two

I was totally unaware of the intersect tool. As simple as it is, I’ve never seen it mentioned and I don’t remember reading about it in the manual. Though it isn’t a perfect solution because it creates extra geometry, it’s much simpler than using a boolean.

#8

Probably