Working with cube map textures

A cube map is a texture that contains six individual 2D textures, comprising six sides of a cube. A useful property of cube maps is that they can be sampled using a direction vector. This comes in handy when you're representing light coming into a scene from different directions. For example, we can store the diffuse part of a physically-based lighting equation in an irradiance cube map.

Loading six faces of a cube map into OpenGL is a fairly straightforward operation. However, instead of just six faces, cube maps are often stored as equirectangular projections or as vertical or horizontal crosses. In this recipe, we will learn how to convert this cube map representation into six faces and load them into OpenGL.

Getting ready

There are many websites that offer high-dynamic range environment textures under various licenses. Check out https://hdrihaven.com and https://hdrmaps.com for useful content.

The complete source code for this recipe...