Three point orientation of the Slice Plane.

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I'm a beginner 3d user, and I wondered if there is an easy way to slice an editable mesh using a plane defined by 3 reference points, on the mesh or other?


It is possible because the Slice Plane can be oriented any way you want it- it is a Gizmo! A Gizmo can be placed/rotated as you wish when in Sub-Object mode.

Here is a (long) workaround to get your 3-point-alignment...

Let's say you have a cylinder you want to slice, and 3 boxes around. You want to pick 3 vertices of the 3 boxes to define the slice plane.

*Right-click the Snap flyout, set Snaps to Vertex only,
*Make sure the Snap flyout is set to 3D Snap.
*Go to Create>Shapes>Line and create a triangular shape by snapping 3 vertices on the surrounding boxes.
*Add an EditMesh modifier to the Shape to get a Mesh.
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*Create a free Camera in the scene.
*While having the Camera selected, hold down the Align flyout and select Camera Align.
*Pick the Triangle Mesh to get a Normal vector to align to.
RESULT - The Camera will be aligned to the mesh plane you defined with 3 points.
*Press C to get the camera display in the viewport
*Now select the cylinder and add a Slice modifier.
*Go into Sub-Object mode to activate the Slice plane editing.
*From the Align flyout, select Viewport Align, confirm the defaults
RESULT: The Slice plane is now aligned to the Viewport (camera) plane.
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*Now Select the usual Object Align command from the flyout and pick the Mesh plane.
*Activate X, Y and Z position and select Pivot Point on the right side of the dialog.
RESULT: Slice Plane is now coincident with the Mesh plane you defined with 3 points.
*If you set the Slice modifier to Remove Top for example, you should see the top of the cylinder being removed along the plane you defined with 3 points...

You can see a screenshot here:

A shorter variation of the above would be to use the Normal Align tool. Since you cannot pick a normal vector on the Slice Plane itself, you have to use some other object that is aligned to the original orientation of the plane.
Starting at the ---- point, it would look like this:

*Add a Slice Modifier
*Go to Sub-Object mode
*Select Normal Align from the Align flyout
*Pick the capping of the cylinder or the top of one of the boxes to select the original orientation
*Pick the Mesh Plane to define the normal vector to align to.
RESULT: The slice plane is now parallel to the Mesh plane.
Go on with the part after the ------ delimiter to align the position too...

This might be a bit too much for a beginner, but it is doable with the right tools in less than a minute.

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Cheers,

Bobo
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