Spatial Index For Lines

I have lots of line segments (that represent various surfaces such as walls, ceilings and floors). I want to efficiently determine which lines are within the player's bounding box

Solution 1:

In just 2 dimensions, where you have good control over the total spatial extend (i.e. know min and max, and these won't increase), grid based approaches such as plain grids or quadtrees work incredibly well. In particular, if you know your query radius (the players box size), a grid of exactly this size should work really well.

Many games also used what is called a BSP tree, a binary space partitioning tree. But for good performance, this tree is AFAIK usually precomputed when the level is built, and then just loaded with the map.