## Math Question, operations with Vectors.

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### Math Question, operations with Vectors.

Hello All,
There are four math operations that I'm still in doubt.

I learnt tow things:
- when you have a matrix, you can rotate it to match a vector orientation
- you can do the inverse: rotate a vector to match the orientation of a matrix.

The questions I have are:
1. The difference between: dMatrix.TransformVector(dVector) and dMatrix.RotateVector(dVector) is that the first changes the size of the vector and second the direction of it?
2. The dMatrix.UntransformVector(dVector) and dMatrix.UnrotateVector(dVector) transforms the vectors to the global matrix, to the previous values they had or to another thing?

I'm studying math, but I'm still in early stages... but I'll arrive there someday!
Developing a racing game.

Posts: 132
Joined: Sat May 17, 2008 9:17 am

### Re: Math Question, operations with Vectors.

Tranform vector chnag eteh orientation and teh poition o f teh vector
rootate vector only chnge teh orientation

Rotatevector only multoply teh vector by teh first 3 x 3 element of teh matrix, those contahet teh rotation part,
Transform multiply the vetor by the 4 x 4 member of the matrix, teh last row in teh translation part.
Julio Jerez
Moderator Posts: 11154
Joined: Sun Sep 14, 2003 2:18 pm
Location: Los Angeles

### Re: Math Question, operations with Vectors.

Thnaks!

Ah, this is good, very good. But what makes the untransform? It divides the vectors instead multiply? This make possible to recover the previous values, right?
Developing a racing game.