ACME-1236 : WIP : Added a min value to vignette

2 files changed, 10 insertions, 5 deletions

diff --git a/indra/llimage/llimage.cpp b/indra/llimage/llimage.cpp
index da22ed5e5b..d84989f9c8 100755
--- a/indra/llimage/llimage.cpp
+++ b/indra/llimage/llimage.cpp
@@ -103,7 +103,8 @@ LLImageBase::LLImageBase()
       mHistoBlue(NULL),
       mHistoBrightness(NULL),
       mVignetteMode(VIGNETTE_MODE_NONE),
-      mVignetteGamma(1.0)
+      mVignetteGamma(1.0),
+      mVignetteMin(0.0)
 {
 }
 
@@ -1280,10 +1281,11 @@ void LLImageRaw::colorCorrect(const U8* lut_red, const U8* lut_green, const U8*
 	}
 }
 
-void LLImageRaw::setVignette(EVignetteMode mode, F32 gamma)
+void LLImageRaw::setVignette(EVignetteMode mode, F32 gamma, F32 min)
 {
     mVignetteMode = mode;
     mVignetteGamma = gamma;
+    mVignetteMin = llclampf(min);
     // We always center the vignette on the image and fits it in the image smallest dimension
     mVignetteCenterX = getWidth()/2;
     mVignetteCenterY = getHeight()/2;
@@ -1293,9 +1295,11 @@ void LLImageRaw::setVignette(EVignetteMode mode, F32 gamma)
 F32 LLImageRaw::getVignetteAlpha(S32 i, S32 j)
 {
     // alpha is a modified gaussian value, with a center and fading in a circular pattern toward the edges
-    // the gamma parameter controls the intensity of the drop down from alpha 1.0 to 0.0
+    // The gamma parameter controls the intensity of the drop down from alpha 1.0 (center) to 0.0
     F32 d_center_square = (i - mVignetteCenterX)*(i - mVignetteCenterX) + (j - mVignetteCenterY)*(j - mVignetteCenterY);
-    return powf(F_E, -(powf((d_center_square/(mVignetteWidth*mVignetteWidth)),mVignetteGamma)/2.0f));
+    F32 alpha = powf(F_E, -(powf((d_center_square/(mVignetteWidth*mVignetteWidth)),mVignetteGamma)/2.0f));
+    // We rescale alpha between min and 1.0 so to avoid complete fading if so desired.
+    return (mVignetteMin + alpha * (1.0 - mVignetteMin));
 }
 
 U32* LLImageRaw::getBrightnessHistogram()
diff --git a/indra/llimage/llimage.h b/indra/llimage/llimage.h
index b9f6a12bdd..404f1c0769 100755
--- a/indra/llimage/llimage.h
+++ b/indra/llimage/llimage.h
@@ -170,6 +170,7 @@ protected:
     S32 mVignetteCenterY;
     S32 mVignetteWidth;
     F32 mVignetteGamma;
+    F32 mVignetteMin;
     
 public:
 	static void generateMip(const U8 *indata, U8* mipdata, int width, int height, S32 nchannels);
@@ -292,7 +293,7 @@ public:
     // Filter Primitives
     void colorTransform(const LLMatrix3 &transform);
     void colorCorrect(const U8* lut_red, const U8* lut_green, const U8* lut_blue);
-    void setVignette(EVignetteMode mode, F32 gamma);
+    void setVignette(EVignetteMode mode, F32 gamma, F32 min);
     U32* getBrightnessHistogram();
 
 protected: