hello.

I’m trying to create an ifc importer(an architectural format).

My problems are at the start:

1)i must use matrixes and vectors , how is knows :

1a)the order of multiplication of the matrix for vector?

1b)the coordinate system (left handed or right handed)?

1c)the matrixes are row major or column major?

after ,

if i have a different axis system , for example in my program i have y on top ,x on left and z inside and in the ifc i have z on top y on left and x inside , how i can import the geometrics items for have the same orientation and correct placing?

ps. the used api is opengl

thanks.