Minor clarifications

libraries/pbrlib/genglsl/lib/mx_prefilter_environment.glsl

@@ -57,6 +57,7 @@ vec3 mx_prefilter_environment()
  float NdotV = 1.0;
  float G1V = mx_ggx_smith_G1(NdotV, alpha);
 
+ // Integrate the LD term for the given environment and alpha.
  vec3 radiance = vec3(0.0, 0.0, 0.0);
  float weight = 0.0;
  int envRadianceSamples = 1024;
@@ -65,7 +66,7 @@ vec3 mx_prefilter_environment()
  vec2 Xi = mx_spherical_fibonacci(i, envRadianceSamples);
 
  // Compute the half vector and incoming light direction.
- vec3 H = mx_ggx_importance_sample_VNDF(Xi, V, vec2(alpha, alpha));
+ vec3 H = mx_ggx_importance_sample_VNDF(Xi, V, vec2(alpha));
  vec3 L = -V + 2.0 * H.z * H;
 
  // Compute dot products for this sample.
@@ -76,7 +77,7 @@ vec3 mx_prefilter_environment()
 
  // Sample the environment light from the given direction.
  vec3 Lw = tangentToWorld * L;
- float pdf = mx_ggx_NDF(H, vec2(alpha, alpha)) * G1V / (4.0 * NdotV);
+ float pdf = mx_ggx_NDF(H, vec2(alpha)) * G1V / (4.0 * NdotV);
  float lod = mx_latlong_compute_lod(Lw, pdf, float($envRadianceMips - 1), envRadianceSamples);
  vec3 sampleColor = mx_latlong_map_lookup(Lw, $envMatrix, lod, $envRadiance);