I've implemented a fps camera based on the up, right and view vectors from this.
Right now I want to be able to interact with the world by placing cubes in a minecraft style.
My lookAt vector is the sum of the view vector and the camera position, so my first attempt was to draw a cube at lookAt, but this is causing a strange behaviour.
I compute every vector like in the web I mentioned (such that lookAt = camera_position + view_direction) but the cube drawn is always arround me. I've tried several things like actually placing it (rounding the lookAt) and it appears near the wanted position but not at the place i'm looking at.
Given these vectors, how can I draw that's centered at the position that my camera is looking but a little bit further (exactly like minecraft)?
It's hard to tell without having images to look at, but lookAt is most likely your normalized forward vector? If i understood you correctly, you'd want to do something like objectpos = camerapos + forward * 10f (where 10f is the distance you want to place the object in front of you in 3d space units) to make sure that it's placed a few units in front of your fps controller.
actually, if view_direction is your normalized forward vector and your lookAt is camera_pos + view_direction, then you'd end up with something very close to your camera position, which would explain why the cube spawns inside you. either way, my suggestion should still work :)