I'm building a game using WebGL and Three.js, and so far I have a terrain with a guy walking on it. I simply cast a ray downwards to know the terrain height.
How can I do this for other 3D objects, like the inside of a house? Is this possible by casting many rays in every direction of the player?
If not, I would like to know how I can achieve the simplest collision detection possible for other meshes. Do you have to cast a ray to every triangle in every mesh nearby?