我们如何在 2D 中通过 Line 角度计算 Rotation3D Axis (Vector3D)

Question

I have some shapes in the 2D and also I have 3D models created exactly by 2D Shapes that I have, Now I want to rotate my 3d models by bottom line of them and I'm usinf from RotateTransform3D and also AxisAngleRotation3D, So I need Angle,CenterPoint and Vector3D of Axis x,y,z.

Angle to rotate model to up is always 90 degrees.

Also I can calculate angle of each line that I want to rotate 3d model by that line ( Red Lines in the example picture) and center point by 2d but my question is how can I calculate Axis to say it should rotate by which axis(or axises).

var myRotateTransform = new RotateTransform3D(
                                 new AxisAngleRotation3D(
                                 new Vector3D(?, ?, ?), angle),
                                 new Point3D(getCenter.X, getCenter.Y, getCenter.Z));

Also in the picture I attached it here you can see and example to understand it better. Example

I believe for 0 degree Vector3D must be (-1,0,0) or for 180 degree Vector3D must be (1,0,0), but how can I calculate it automatically?

Answer 1

If you want to rotate the object around the red lines, you need to calculate the direction of the line. Ie calculate end - start . This direction can then be used as the rotation-axis. You might also want to use a point on said line as the rotation-center since this will make the rotation work similar to a hinge.

You do not specify how you are describing the lines, so it is difficult to provide more specific instructions.