2 files changed, 9 insertions, 0 deletions
diff --git a/indra/llinventory/llsettingssky.cpp b/indra/llinventory/llsettingssky.cpp
index 00c1edb55a..82c67a1066 100644
--- a/indra/llinventory/llsettingssky.cpp
+++ b/indra/llinventory/llsettingssky.cpp
@@ -1209,6 +1209,14 @@ LLColor3 LLSettingsSky::getLightTransmittance(F32 distance) const
     return transmittance;
 }
 
+// SL-16127: getTotalDensity() and getDensityMultiplier() call LLSettingsSky::getColor() and LLSettingsSky::getFloat() respectively which are S-L-O-W
+LLColor3 LLSettingsSky::getLightTransmittanceFast( const LLColor3& total_density, const F32 density_multiplier, const F32 distance ) const
+{
+    // Transparency (-> density) from Beer's law
+    LLColor3 transmittance = componentExp(total_density * -(density_multiplier * distance));
+    return transmittance;
+}
+
 // performs soft scale clip and gamma correction ala the shader implementation
 // scales colors down to 0 - 1 range preserving relative ratios
 LLColor3 LLSettingsSky::gammaCorrect(const LLColor3& in) const
diff --git a/indra/llinventory/llsettingssky.h b/indra/llinventory/llsettingssky.h
index 4127911643..77d9d8e87c 100644
--- a/indra/llinventory/llsettingssky.h
+++ b/indra/llinventory/llsettingssky.h
@@ -252,6 +252,7 @@ public:
 
     LLColor3 getLightAttenuation(F32 distance) const;
     LLColor3 getLightTransmittance(F32 distance) const;
+    LLColor3 getLightTransmittanceFast(const LLColor3& total_density, const F32 density_multiplier, const F32 distance) const;
     LLColor3 getTotalDensity() const;
     LLColor3 gammaCorrect(const LLColor3& in) const;