Chapter 3, coordinate systems & translation

#1 Q1 :
At the end of this thread there is a discussion about the "handed-ness" of the pictures in the book. As you will see, the pictures are correct.

Q2 :
Translation is often made before rotation cause rotation is done according to the center of the coordinate system. If you rotate first, you'll actually be moving your shape from one point to the other X degrees around the desired axis. So what you do is : trasnlate to origin, apply scale ( in the axis you want ), then rotate, then translate it back to the desired location.

Q3 :
No, because the Z axis points down.

#2 Q1: Thanks, I see how the "handed-ness" works out now

Q2: I understand what you are saying. The books states under the "full transformation" section on pg. 97 that "the transformations applied are scale...followed by rotation...and then finally translation". It then follows up with the caption for figure 3.17 "In the great majority of cases, the correct order is scaling, rotation, then transformation".

I understand that order is important and you can get different results based on order. So I am basically wondering if the book is incorrect when it says translation is applied first? Is the book incorrect when it says the correct order is scaling, rotation, then translation? Is the book just incorrect when it says the majority of cases go scale, rotation, translate?

It seems that the book says two mutually exclusive things and I am just trying to sort it out :)

Q3: I don't understand how the Z points down. Figure 3.4 shows it pointing up. Also on page 91 when describing the orientation of the system within Torque the author states "Don't forget that positive Z would be up, and negative Z would be down."

#3 Q3: It points down in one of the right-hand example. In Torque it points up :-)