[gameprogrammer] Re: basic vector math
- From: "Alan Wolfe" <alan.wolfe@xxxxxxxxx>
- To: gameprogrammer@xxxxxxxxxxxxx
- Date: Wed, 23 Jul 2008 11:05:10 -0700
Here's a trick a very talented person i work with taught me :P
If you have your 3x3 matrix representing rotation, translation, scaling, etc
each row of the matrix represents a "relative axis"
like if you had this matrix (totally made up):
1, 4, 5
2, 8, 2
9, 3, 2
if you wanted to know which direction was left and right you'd take the top
row (1,4,5) as a vector and normalize it. That will give you the "right"
vector, and you can multiply the vector by -1 to get the "left" vector.
The 2nd row of the matrix is the Up/Down (Y) vector.
The 3rd row of the matrix is the forward/back (Z) vector.
cool huh?
Not sure how that applies to 4x3 or 4x4 matrices though :P
On 7/23/08, Roger Durañona <luo_hei@xxxxxxxx> wrote:
>
> I have a little math problem here. I have an opengl camera system with a
> target coord (where the camera looks) and a camera position. The view is
> isometric like, and I need to move the camera simulating scroll up, down,
> left and right. My problem is, how do I calculate the coordinate translation
> in a way that no matter the target/camera position, the scroll left always
> move the camera to the left and so on?
>
> --
> "La naturaleza y sus leyes yacían ocultas en la noche, Dios dijo , "Sea
> Newton" y todo fue luz", Alexander Pope
> "Pero esto no fue lo último. El diablo gritó "Sea Einstein", y se
> restableció la situación", John Collins Squire
>
>
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