how to draw a tilted circle?

Hai,

The following code draws a circle in the x-z plane in 3D.

radius=1;
center=[2 4 2];
theta=linspace(0,2*pi);
rho=ones(1,100).*radius;
[x,z]=pol2cart(theta,rho);
x=x+center(1);
z=z+center(3);
y=center(2)*ones(1,length(x));
figure;
h=plot3(x,y,z);
grid on;
axis square;

By default the above circle is vertical in the x-z plane. I need to draw a circle which is inclined or tilted at some angle. How could I do this?

Looking forward for your reply.

BSD

[Walter Roberson]

Duplicate is at http://www.mathworks.com/matlabcentral/answers/17160-how-to-draw-an-inclined-circle

Answer 1

[Jan]

You have X-, Y- and Z-coordinates. Now you want to tilt the obejct. This can be done by applying a rotation matrix, e.g. for a rotation around the Z-axis by the angle a :

R = [ cos(a), sin(a), 0; ...
     -sin(a), cos(a), 0; ...
      0,      0,      1];

This matrix must be multiplied to the array of coordinates. See also: Wiki: Rotation Matrix

[bsd]

The circle is getting tilted, but the location of the circle is changing. I need the circle to tilt at the same location, where it is vertical. What could be done?

BSD

[bsd]

I meant, something like tilting around the same center, i.e. the face of the circle should tilt or rotate around its center.

http://www.google.co.in/search?hl=en&q=atom&gs_sm=e&gs_upl=2900l3348l0l3711l4l4l0l0l0l0l376l1067l3-3l3l0&bav=on.2,or.r_gc.r_pw.,cf.osb&biw=1143&bih=668&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi

Go to the above the link, and see the tilted circles in the structure of the atom, around the same center.

BSD

[Walter Roberson]

Generate the circle around (0,0,0), rotate it, and then translate the circle by the coordinates of the new center that you want.

Or if you already have a circle existing and decide later that you want to tilt it, then translate it to (0,0,0), rotate it, and then translate it back.

[bsd]

It is working. Excellent... Thank you...

BSD

Answer 2

[Walter Roberson]

The answer hasn't changed since your previous time asking.

If you wish to do it mathematically instead of the way I suggested before, then say as much (at which point I would say, "So, did you read the documentation to find out what that routine actually does ?")

[Jan]

@Walter: Your answer has been complete. I add more details only, because it seems that the OP cannot follow completely.