Properly remap roughness when reading from radiance map

This ensures that we consistently use perceptual roughness which matches the behaviour of most other PBR renderers like Blender, Ue4 and Godot 3

1 files changed, 2 insertions, 1 deletions

diff --git a/servers/rendering/renderer_rd/effects/copy_effects.cpp b/servers/rendering/renderer_rd/effects/copy_effects.cpp
index a05db8c563..f94abd66d7 100644
--- a/servers/rendering/renderer_rd/effects/copy_effects.cpp
+++ b/servers/rendering/renderer_rd/effects/copy_effects.cpp
@@ -1153,7 +1153,8 @@ void CopyEffects::cubemap_roughness(RID p_source_rd_texture, RID p_dest_texture,
 	memset(&roughness.push_constant, 0, sizeof(CubemapRoughnessPushConstant));
 
 	roughness.push_constant.face_id = p_face_id > 9 ? 0 : p_face_id;
-	roughness.push_constant.roughness = p_roughness * p_roughness; // Shader expects roughness, not perceptual roughness, so multiply before passing in.
+	// Remap to perceptual-roughness^2 to create more detail in lower mips and match the mapping of cubemap_filter.
+	roughness.push_constant.roughness = p_roughness * p_roughness;
 	roughness.push_constant.sample_count = p_sample_count;
 	roughness.push_constant.use_direct_write = p_roughness == 0.0;
 	roughness.push_constant.face_size = p_size;