I need some other information though :

1. What does "Frame in which input force is resolved" mean ?

2. Also, is there an option somewhere to have forces vectors "nose out" ?

3. Can I setup the initial position of the camera ?

4. I would like to have sliders to easily setup my simulation, just like in this demonstration. Are they available in SM as in Mathematica ?

I missed that you had replied to this thread, sorry!

I am glad that you found my tutorial helpful!

You can think of framea and frameb as two points in a coordinate system. The vector r[3] will describe their relative displacement from one another. If framea is in at {0,0,0}, and r[3]={1,1,0} then frameb will be located one unit along the x-axis and up one unit along the y-axis.

The BodyBox component will draw a rectangular parallelpiped between the origin and frameb. The location of the origin is determined by rshape[3] which is the vector from the point defined by framea to the box origin. The length of the body will be determined by the length of the vector r[3]-rshape[3], in Modelica written as:

Modelica.Math.Vectors.length(r - r_shape)

So if we use the previous example where framea is at point {0,0,0} and r[3]={1,1,0} then, as mentioned previously, frameb will be at point {1,1,0}. If r_shape[3]={0,1,0} then a body will be drawn between {1,0,0} since

r-r_shape={1,1,0}-{0,1,0}={1,0,0}

i.e one unit distance along the x-axis and it will have length 1. The width and height of the box is set by the width and height parameters respectively.

I have, however, never seen anyone use anything beside rshape[3]={0,0,0} which then means a body will be drawn between framea and frame_b. (As long as you haven't changed the length or lengthDirection parameters).

What is it you are trying to accomplish? Maybe I can be of better use if I know more.

Thank you very much Patrik, for your time and efforts.

I learned a lot more studying your tutorial this morning than during last few days.

A couple of things should be clarified though, regarding coordinates :

I understood r[3] and r_shape[3] decide of the position of a point of the BodyBox (Which point ?) and its orientation, but I can't figure out what frames are : on a Multibody/Parts/BodyBox, it looks like frame_a and frame_b aren't specific points on the box itself, like center of faces, what are they exactly ?