From e3bf55a266196a22549b8ae79a80f16cbadf8c0a Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Wed, 11 Dec 2013 12:00:27 +0000
Subject: [PATCH] Added initial support for 1D transfer functions to
 MultipassTechnique

---
 examples/osgvolume/osgvolume.cpp     | 11 +++++--
 src/osgVolume/MultipassTechnique.cpp | 47 ++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+), 2 deletions(-)

diff --git a/examples/osgvolume/osgvolume.cpp b/examples/osgvolume/osgvolume.cpp
index 37d333655..c5fcd8a31 100644
--- a/examples/osgvolume/osgvolume.cpp
+++ b/examples/osgvolume/osgvolume.cpp
@@ -1067,6 +1067,7 @@ int main( int argc, char **argv )
         sp->setActiveProperty(0);
 
         osgVolume::AlphaFuncProperty* ap = new osgVolume::AlphaFuncProperty(alphaFunc);
+        osgVolume::IsoSurfaceProperty* isop = new osgVolume::IsoSurfaceProperty(alphaFunc);
 
         // SampleDensity is now deprecated
         osgVolume::SampleDensityProperty* sd = new osgVolume::SampleDensityProperty(0.005f);
@@ -1087,7 +1088,13 @@ int main( int argc, char **argv )
             cp->addProperty(tp);
 
             if (sdwm) cp->addProperty(sdwm);
-            if (tfp) cp->addProperty(tfp);
+            if (tfp)
+            {
+                OSG_NOTICE<<"Adding TransferFunction"<<std::endl;
+                cp->addProperty(tfp);
+            }
+
+            cp->addProperty(isop);
 
             sp->addProperty(cp);
         }
@@ -1112,7 +1119,7 @@ int main( int argc, char **argv )
             if (useMultipass) cp->addProperty(sr);
             else cp->addProperty(sd);
             cp->addProperty(tp);
-            cp->addProperty(new osgVolume::IsoSurfaceProperty(alphaFunc));
+            cp->addProperty(isop);
             if (sdwm) cp->addProperty(sdwm);
             if (tfp) cp->addProperty(tfp);
 
diff --git a/src/osgVolume/MultipassTechnique.cpp b/src/osgVolume/MultipassTechnique.cpp
index 5bd822169..2ae1f0097 100644
--- a/src/osgVolume/MultipassTechnique.cpp
+++ b/src/osgVolume/MultipassTechnique.cpp
@@ -147,6 +147,8 @@ void MultipassTechnique::init()
     Locator* masterLocator = _volumeTile->getLocator();
     Locator* layerLocator = _volumeTile->getLayer()->getLocator();
 
+    osg::TransferFunction1D* tf = 0;
+
     if (!masterLocator && layerLocator) masterLocator = layerLocator;
     if (!layerLocator && masterLocator) layerLocator = masterLocator;
 
@@ -202,6 +204,17 @@ void MultipassTechnique::init()
         else
             stateset->addUniform(new osg::Uniform("AlphaFuncValue",alphaFuncValue));
 
+
+        if (cpv._isoProperty.valid())
+            stateset->addUniform(cpv._isoProperty->getUniform());
+        else
+            stateset->addUniform(new osg::Uniform("IsoSurfaceValue",alphaFuncValue));
+
+        if (cpv._tfProperty.valid())
+        {
+            tf = dynamic_cast<osg::TransferFunction1D*>(cpv._tfProperty->getTransferFunction());
+        }
+
 #if 1
         osg::ref_ptr<osg::TexGen> texgen = new osg::TexGen;
         texgen->setMode(osg::TexGen::OBJECT_LINEAR);
@@ -269,6 +282,40 @@ void MultipassTechnique::init()
         OSG_NOTICE<<"Texture Dimensions "<<image_3d->s()<<", "<<image_3d->t()<<", "<<image_3d->r()<<std::endl;
     }
 
+    if (tf)
+    {
+        OSG_NOTICE<<"Setting up TransferFunction"<<std::endl;
+
+        float tfScale = 1.0f;
+        float tfOffset = 0.0f;
+
+        ImageLayer* imageLayer = dynamic_cast<ImageLayer*>(_volumeTile->getLayer());
+        if (imageLayer)
+        {
+            tfOffset = (imageLayer->getTexelOffset()[3] - tf->getMinimum()) / (tf->getMaximum() - tf->getMinimum());
+            tfScale = imageLayer->getTexelScale()[3] / (tf->getMaximum() - tf->getMinimum());
+        }
+        else
+        {
+            tfOffset = -tf->getMinimum() / (tf->getMaximum()-tf->getMinimum());
+            tfScale = 1.0f / (tf->getMaximum()-tf->getMinimum());
+        }
+        osg::ref_ptr<osg::Texture1D> tf_texture = new osg::Texture1D;
+        tf_texture->setImage(tf->getImage());
+
+        tf_texture->setResizeNonPowerOfTwoHint(false);
+        tf_texture->setFilter(osg::Texture::MIN_FILTER, osg::Texture::LINEAR);
+        tf_texture->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR);
+        tf_texture->setWrap(osg::Texture::WRAP_R,osg::Texture::CLAMP_TO_EDGE);
+
+        unsigned int transferFunctionTextureUnit = volumeTextureUnit+1;
+
+        stateset->setTextureAttributeAndModes(transferFunctionTextureUnit, tf_texture.get(), osg::StateAttribute::ON);
+        stateset->addUniform(new osg::Uniform("tfTexture",int(transferFunctionTextureUnit)));
+        stateset->addUniform(new osg::Uniform("tfOffset",tfOffset));
+        stateset->addUniform(new osg::Uniform("tfScale",tfScale));
+
+    }
 
 
     osg::ref_ptr<osg::Shader> computeRayColorShader = osgDB::readRefShaderFile(osg::Shader::FRAGMENT, "shaders/volume_compute_ray_color.frag");