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myk45
05-12-2012, 04:12 AM
Hello All!

I am reading these wonderful set of articles by Jason L. McKesson. I am currently reading the translation article:

http://www.arcsynthesis.org/gltut/Positioning/Tut06%20Translation.html

>>This is a translation transformation: it is used to position the origin point of the initial space relative to the destination space. Since all of the coordinates in a space are relative to the origin point of that space, all a translation needs to do is add a vector to all of the coordinates in that space. The vector added to these values is the location of where the user wants the origin point relative to the destination coordinate system.

Now, my question is, Why can't we consider this scenario as transforming a coordinate instread of transforming a coordinatee system? I am confused as to why Jason mentions it as moving to a new coordinate system, instead of moving the coordinates of the point?

I also remember reading in 3D Math Primer for Graphics and Game Development that transforming a coordinate is not the same as coordinate system transformation(and that they would be opposite to each other).

But, since they yield the same result, can't we use any point of view, i.e seeing it as a coordinate transformation of a transformation of the coordinate system?

PS: Please provide links of threads if a similar question has already been asked.

Thanks!

Dark Photon
05-12-2012, 07:27 PM
my question is, Why can't we consider this scenario as transforming a coordinate instread of transforming a coordinatee system? ... I also remember reading in 3D Math Primer for Graphics and Game Development that transforming a coordinate is not the same as coordinate system transformation(and that they would be opposite to each other).
You are on the right track. You can visualize it either way: transforming objects within a coordinate system or transforming coordinate systems. The OpenGL Programming Guide also has a good description of this.

myk45
05-14-2012, 02:43 AM
Thanks for the reply Dark Photon. I read the Red Book. So, i understand that both the cases are essentially doing the same: changing the modelview matrix, so we can visualize any of them. Thanks!