Quote Originally Posted by Paulius
To see if it?¢_Ts on the left or right you need to transform you?¢_Tre destination point so it?¢_~s coordinate system is the same as you?¢_Tre cars and check if it?¢_Ts X component is positive or not. To do the transformation you need to multiply that point by a translation matrix to move it?¢_Ts zero point to the cars position then by inverse or you?¢_Tre cars rotation matrix.
Ehm ok.. let's take a step at a time! :mrgreen:

I've the vector "position" of the car, the matrix "rotation" of the car and the "target" vector for where i want to drive to.

First, i obtain the 4x4 matrix that translate the origin to the car for both position and orientation, right ?

Then, i multiply the "target" by that matrix, and i get the "target" transformed to the new origin (the car). How do i do this multiplication?

Now, i check the X axis (that's easy.. )

Ok, i think i've understood the method.. now the problem is implementing it

Thank!

PS Paulius, maybe do you have a nice matrix calculation unit ?

PPS Anyone knows if the ODE matrices are compatible to the OpenGL ones ? Are they arranged in the same way in memory ?