1 files changed, 5 insertions, 3 deletions
diff --git a/source/blender/draw/engines/eevee/shaders/lightprobe_lib.glsl b/source/blender/draw/engines/eevee/shaders/lightprobe_lib.glsl
index fe4f3dcaa2f..5e78fae5b82 100644
--- a/source/blender/draw/engines/eevee/shaders/lightprobe_lib.glsl
+++ b/source/blender/draw/engines/eevee/shaders/lightprobe_lib.glsl
@@ -167,7 +167,7 @@ vec3 probe_evaluate_cube(int pd_id, vec3 W, vec3 R, float roughness)
    * http://www.frostbite.com/wp-content/uploads/2014/11/course_notes_moving_frostbite_to_pbr.pdf
    */
   float original_roughness = roughness;
-  float linear_roughness = sqrt(roughness);
+  float linear_roughness = fast_sqrt(roughness);
   float distance_roughness = saturate(dist * linear_roughness / length(intersection));
   linear_roughness = mix(distance_roughness, linear_roughness, linear_roughness);
   roughness = linear_roughness * linear_roughness;
@@ -175,12 +175,14 @@ vec3 probe_evaluate_cube(int pd_id, vec3 W, vec3 R, float roughness)
   float fac = saturate(original_roughness * 2.0 - 1.0);
   R = mix(intersection, R, fac * fac);
 
-  return textureLod_cubemapArray(probeCubes, vec4(R, float(pd_id)), roughness * prbLodCubeMax).rgb;
+  float lod = linear_roughness * prbLodCubeMax;
+  return textureLod_cubemapArray(probeCubes, vec4(R, float(pd_id)), lod).rgb;
 }
 
 vec3 probe_evaluate_world_spec(vec3 R, float roughness)
 {
-  return textureLod_cubemapArray(probeCubes, vec4(R, 0.0), roughness * prbLodCubeMax).rgb;
+  float lod = fast_sqrt(roughness) * prbLodCubeMax;
+  return textureLod_cubemapArray(probeCubes, vec4(R, 0.0), lod).rgb;
 }
 
 vec3 probe_evaluate_planar(int id, PlanarData pd, vec3 W, vec3 N, vec3 V, float roughness)