Here is a list of all documented variables with links to the struct/union documentation for each field:

aabb : AT_Triangle
absorption : AT_Material
arr : AT_Vec3
direction : AT_Source
environment : AT_SceneConfig
fps : AT_Settings
intensity : AT_Source
material : AT_SceneConfig
max : AT_AABB
min : AT_AABB
num_rays : AT_Settings
num_sources : AT_SceneConfig
position : AT_Source
scattering : AT_Material
sources : AT_SceneConfig
v1 : AT_Triangle
v2 : AT_Triangle
v3 : AT_Triangle
voxel_size : AT_Settings
x : AT_Vec3i
y : AT_Vec3i
z : AT_Vec3i