Most of the PBR tutorials out there use HDR maps loaded from disk. But in games these maps need to be generated by taking snapshots of the scene from the objects location which is where problems arise.
Let's say there are just 2 objects with PBR material a sphere and a cube.
Here are 2 problems I come across
1)Each of these 2 objects need an full 360 degree view of the scene around them stored in an cubemap for proper IBL implementation which means for just 2 objects we have to render our scene 12 times!!![6 times to fill the cube map of each object] which is ridiculously expensive and this is just for 2 objects. Is there an alternative to this especially in dynamic scenes where objects move around all the time?
2)If the sphere and the cube are very close to each other then the color of one object will depend on the light reflected from the other and this light can bounce an infinite number of times between the objects. This can be solved using recursive ray tracing where we control the bounces using an depth variable. Is there an similar recursive approach for the raserization pipeline ?[Similar to 2 mirrors facing each other and reflecting each other problem]
Some theory, ideas or maybe some linked articles would be of great help