Fix some Microfacet bugs

Cargo.lock

@@ -1382,6 +1382,12 @@ dependencies = [
  "windows-targets 0.52.6",
 ]
 
+[[package]]
+name = "libm"
+version = "0.2.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8355be11b20d696c8f18f6cc018c4e372165b1fa8126cef092399c9951984ffa"
+
 [[package]]
 name = "libredox"
 version = "0.1.3"
@@ -1662,6 +1668,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "071dfc062690e90b734c0b2273ce72ad0ffa95f0c74596bc250dcfd960262841"
 dependencies = [
  "autocfg",
+ "libm",
 ]
 
 [[package]]
@@ -2105,6 +2112,16 @@ dependencies = [
  "getrandom",
 ]
 
+[[package]]
+name = "rand_distr"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "32cb0b9bc82b0a0876c2dd994a7e7a2683d3e7390ca40e6886785ef0c7e3ee31"
+dependencies = [
+ "num-traits",
+ "rand",
+]
+
 [[package]]
 name = "rav1e"
 version = "0.7.1"
@@ -2201,6 +2218,7 @@ dependencies = [
 name = "ray-tracing-material"
 version = "0.1.0"
 dependencies = [
+ "rand_distr",
  "ray-tracing-core",
 ]