Hi JeromeOliver, we need to change the forum soon, this is not supposed to be here. Other will not find it, as it is a Tutorial Suggestion, not a Cineversity Q&A. It sounds perhaps trivial—but after a while the complete forum would be just noise if we keep things not organized.
The Matrix. It is certainly even in Hands on classes a part of information that has a longer digesting time.
The simple way to explain it is, from the four you have one for the position in space: The Offset. That is pretty simple I guess, as it is similar to the position of an object.
The other three are—well, some will say more abstract. Lets start with one of the X,Y,Z arrows that you see when you select an object in “Move” mode. The red, green and blue arrow. OK, each them represents an vector, Vectors hare based in photographic terms on a point of view (where the camera is) and a point of interest (the subject to be photographed). between the two points you will have a distance. with this information, one will get a vector (or arrow if you like).
To define two points in space you need for each point three positions: X,Y and Z. To have not for each arrow or vector six numbers “Point of View XYZ” and “Point of Interest XYZ”, they all share the Offset XYZ values, the origin, or the first vector in the Matrix.
As these arrows are not always perpendicular to each other, nor have the same length always, these three values define the end point of the vector (point of interest—if that helps)
In that way every single object is defined in C4D. It has a position and how it is scaled or rotated will be expressed with these v1, v2, v3 or the three other vectors besides the Offset.
Any rotation or scale is expressed that way. I try normally to explain it that each vector X, Y or Z is defined by three invisible “sub-vectors”
This is the most complicated to grasp format in XPresso, and I haven’t seen a lot of people in the past ten years who got it in the first moment. The reason that I see for that is the image of the XYZ axis system and the idea that we talk on C4D surface in PSR (Position, Scale and Rotation) values, but internally it is translated in the Matrix. It is the base of the calculation inside of C4D.
I hope I could put a little bit more light on it.
Let me know if that has helped.
All the best
Sassi