Merged in davep/DRTVWR-440 (pull request #48)

SL-12902 Fix for doing the technically correct but compatibility wrong thing WRT light color values.

1 files changed, 13 insertions, 4 deletions

diff --git a/indra/llmath/llmath.h b/indra/llmath/llmath.h
index 57f2489a2d..8f01ad6c1c 100644
--- a/indra/llmath/llmath.h
+++ b/indra/llmath/llmath.h
@@ -537,9 +537,12 @@ inline void ll_remove_outliers(std::vector<VEC_TYPE>& data, F32 k)
 	}
 }
 
-// This converts from a non-linear sRGB floating point value (0..1) to a linear value.
-// Useful for gamma correction and such.  Note: any values passed through this should not be serialized.  You should also ideally cache the output of this.
-inline float sRGBtoLinear(const float val) {
+// Converts given value from a linear RGB floating point value (0..1) to a gamma corrected (sRGB) value.
+// Some shaders require color values in linear space, while others require color values in gamma corrected (sRGB) space.
+// Note: in our code, values labeled as sRGB are ALWAYS gamma corrected linear values, NOT linear values with monitor gamma applied
+// Note: stored color values should always be gamma corrected linear (i.e. the values returned from an on-screen color swatch)
+// Note: DO NOT cache the conversion.  This leads to error prone synchronization and is actually slower in the typical case due to cache misses
+inline float linearTosRGB(const float val) {
     if (val < 0.0031308f) {
         return val * 12.92f;
     }
@@ -548,7 +551,13 @@ inline float sRGBtoLinear(const float val) {
     }
 }
 
-inline float linearTosRGB(const float val) {
+// Converts given value from a gamma corrected (sRGB) floating point value (0..1) to a linear color value.
+// Some shaders require color values in linear space, while others require color values in gamma corrected (sRGB) space.
+// Note: In our code, values labeled as sRGB are gamma corrected linear values, NOT linear values with monitor gamma applied
+// Note: Stored color values should generally be gamma corrected sRGB.  
+//       If you're serializing the return value of this function, you're probably doing it wrong.
+// Note: DO NOT cache the conversion.  This leads to error prone synchronization and is actually slower in the typical case due to cache misses.
+inline float sRGBtoLinear(const float val) {
     if (val < 0.04045f) {
         return val / 12.92f;
     }