draw a cube in direction of a vector!

i am absolutle begginer in opengl(in fact it’s my first program)
i want to draw a cube in direction of a vector!
i need this to draw a robotic arm.
i just have 2 points which shows begin and end of arm(a cube for example) and i want to draw in direction of vector of that 2 points!
i searched a lot but nothing seems to do that.
is there any way that i can do this?
sorry for my bad english

you’ll need another vector to know which way is up in order to position the cube otherwise you don’t know which way it’s tilted along it’s z axis, if there’s no roll involved use vector3(0.0,1.0,0.0) that will point up in world coordinates. You also need the dimensions of the cube. so given:

up Vector(0,1,0);
Zvector(direction the cube is oriented, obtained by point2-point1)
Xvector(Obtained from the cross product of up and Z)
YVector(Cross product of Xvector and Zvector)
and it’s position

You can create a transformation matrix (xvector,yvector,zvector,position). use that as your model matrix to position your cube.

thanks a lot.
but as i said i’m beginner and i don’t know how i can create that matrixes, cross product them, create tranformation matrix and use it as a model matrix :frowning: :frowning:
my program is big itself and i can’t start to calculate cross matrixes with c++ in order to draw that cube.
is there any way opengl do all that and i just give to it vector of direction and up vector?
if any one can please post an opengl code which for example draw a cube in direction of (1,1,1).
thanks in advance