Debug veach-mis/mis.pbrt

[wahn]

After having implemented pub fn create_ply_mesh(...) (see issue #27) I noticed that the C++ version renders the current test scene (veach-mis/mis.pbrt) differently from the Rust version.

C++ version of PBRT:

Rust version of PBRT:

Let's debug, why ...

[wahn]

> imf_diff -d -f pbrt_rust.exr mis.exr diff.jpg
differing pixels:	 32.946% (327923 of 995328)
average difference:	 30.838%
maximum difference:	 77.548%
Summary: Many pixels differ strongly.
== "pbrt_rust.exr" and "mis.exr" are different

[wahn]

The last commit (5862894) indeed fixes the problem:

> imf_diff -d -f pbrt_rust.exr mis.exr diff.jpg
differing pixels:	  0.000% (1 of 995328)
average difference:	  1.109%
maximum difference:	  1.109%
Summary: 1 pixel differs slightly.
== "pbrt_rust.exr" and "mis.exr" are similar

Basically the ParamSet::copy_from(...) did not copy boolean parameters. Therefore the remaproughness value was set to the default value true instead of the value specified in the file (false):

> grep remaproughness assets/scenes/veach-mis/mis.pbrt
    Material "plastic" ... "bool remaproughness" ["false"]
    Material "plastic" ... "bool remaproughness" ["false"]
    Material "plastic" ... "bool remaproughness" ["false"]
    Material "plastic" ... "bool remaproughness" ["false"]