Hi all

I've two matrix questions (I'm using Direct3d so i need appropriate answers):

1. Are the rows of the upper-left part (3x3) of a matrix the base-vectors for the coordinate system, the matrix defines. To be more specific:
Is e.g the following vector [_11,_12,_13] the X axis for the new coordinate system?? :?

2.I dont understand why Direct3d uses 4x4 matrices instead of 3x3. The coordinates all have 3 components so you would expect a 3x3 matrix,
i know one row (_41,_42,_43) is ment for translation values.. Example:



This shows how a vector is multiplied/transformed using a matrix, but i miss one column (_14,_24,_34,_44).
It seems that sometimes vectors with 4 components are used.

I was trying to understand the matrix on this page:

D3DXMatrixPerspectivefovLH

But i don't know what the function of the 1.0 is (4th column, third row). :?

Can anyone explain the function of the 4th component and the last matrix-column

Thank you