book2 in cornell box , the light only illuminates one area

[endiow]

The light source does not emit light in all directions

but the simple light scene renders right

I really don't know where I went wrong， My code is here：https://github.com/endiow/RayTracing-The-next-week/tree/main/RayTracing_1

Can somenoe help me, pls :(

[whydoubt]

Don't know if you ever resolved this, but I do see what happened.

Your function random_double(double min, double max) creates a static uniform_real_distribution. The function is called the first time with (0, 1). When the function is later called with (-1, 1) it still uses the (0, 1) range.