Rotating a Cylinder to fit the line x=y=z

[sig_1, sig_2, sig_3] = cylinder;
%sig_3 = sig_3 * 2;

g = surf(sig_1,sig_2,sig_3);


direction =[1 1 1];
rotate(g,direction, 45)

xlabel("x");
ylabel("y");
zlabel("z");


title('Von Mises Yield Surface')
hold on

Q = plot3([0 2], [0 2], [0 2]);
hold off

Hey everyone, I am new to matlab and am trying to figure out how I would be able to rotate a cylinder to fit the line y=x=z, like a von mises surface. Could i use the line as a refrence point for my cylinder? Or am i rotating my surface wrong?

Any help or refrence to a source that might help will be greatly appreciated

[KSSV]

Get the angle of line and then rotate cyclinder by this angle.

Answer 1

[DGM]

The vector you're using is the vector you're trying to align the cylinder to. The vector you need to be specifying is the axis of rotation, which should be orthogonal to [1 1 1]. It also seems that rotate() likes to move the origin around depending on the plot box, so you'll have to make it stop doing that by explicitly specifying a coordinate origin. Lastly, the rotation angle isn't 45 degrees.

clf
[sig_1, sig_2, sig_3] = cylinder;
g = surf(sig_1,sig_2,sig_3);

rotaxis = [135 0]; % i decided to do this polar instead of cart
rotate(g,rotaxis,90-atand(1/sqrt(2)),[0 0 0])

xlabel('x');
ylabel('y');
zlabel('z');
title('Von Mises Yield Surface')
hold on
axis equal

Q = plot3([0 2], [0 2], [0 2]);
Q = plot3([1 -1], [-1 1], [0 0]);
hold off

And like I said, the angle isn't 45. It's easy enough to derive, though.

[Kevin Hanekom]

You are my savior! Thank you for the help!! But yes i see now, theta is = 45 but that doesnt necessarily mean that phi also = 45.

Again, Thank you!