From d773d358c436143e06854bba3d9c603df918f3db Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Tue, 1 Apr 2014 18:56:57 +0000
Subject: [PATCH] Improved the setting of sample density/ratio so that they are
 consistent

---
 src/osgVolume/Property.cpp | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/src/osgVolume/Property.cpp b/src/osgVolume/Property.cpp
index 8f7a085b5..de688ddd0 100644
--- a/src/osgVolume/Property.cpp
+++ b/src/osgVolume/Property.cpp
@@ -452,7 +452,8 @@ bool PropertyAdjustmentCallback::handle(const osgGA::GUIEventAdapter& ea,osgGA::
         if (ea.getMouseYOrientation()==osgGA::GUIEventAdapter::Y_INCREASING_DOWNWARDS) v = 1.0f-v;
 
         float v2 = v*v;
-        float v4 = v2*v2;
+        float sampleRatio = powf((1.0f-v)*2.0f,3.0f);
+        float sampleDensity = (1.0/sampleRatio)/512.0f;
 
         if (_updateAlphaCutOff && cpv._isoProperty.valid())
         {
@@ -480,26 +481,23 @@ bool PropertyAdjustmentCallback::handle(const osgGA::GUIEventAdapter& ea,osgGA::
 
         if (_updateSampleDensity && cpv._sampleDensityProperty.valid())
         {
-            OSG_NOTICE<<"Setting sample density to "<<v4<<std::endl;
-            cpv._sampleDensityProperty->setValue(v4);
+            OSG_NOTICE<<"Setting sample density to "<<sampleDensity<<std::endl;
+            cpv._sampleDensityProperty->setValue(sampleDensity);
         }
         if (_updateSampleDensity && cpv._sampleDensityWhenMovingProperty.valid())
         {
-            OSG_INFO<<"Setting sample density when moving to "<<v4<<std::endl;
-            cpv._sampleDensityWhenMovingProperty->setValue(v4);
+            OSG_INFO<<"Setting sample density when moving to "<<sampleDensity<<std::endl;
+            cpv._sampleDensityWhenMovingProperty->setValue(sampleDensity);
         }
 
         if (_updateSampleDensity && cpv._sampleRatioProperty.valid())
         {
-            float sampleDensity = v4;
-            float sampleRatio = 1.0/(512*sampleDensity);
             OSG_NOTICE<<"Setting sample ratio to "<<sampleRatio<<std::endl;
             cpv._sampleRatioProperty->setValue(sampleRatio);
         }
 
         if (_updateSampleDensity && cpv._sampleRatioWhenMovingProperty.valid())
         {
-            float sampleRatio = (1.0-v2)*20.0;
             OSG_NOTICE<<"Setting sample ratio to "<<sampleRatio<<std::endl;
             cpv._sampleRatioWhenMovingProperty->setValue(sampleRatio);
         }