As I understood the only method to compute collisions with three.js is intersectObjects
with a ray ...
I created an object that includes the basic elements of the collision : ground, walls, objects, stairs. with the firstpersoncontrols. I went with the idea that I should calculate the steering vector based on the direction in which the camera is currently traveling but it does not really work and I do not see where the error is.
I expected that the camera can not pass through ground, walls and objects with which she finds herself in a collision.
You can see the code here