From d2c2ef3ec915491c7586b5f1f10b1560492dbb43 Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Mon, 25 Jun 2018 20:02:30 +0100
Subject: [PATCH] Moved osg::clampProjectionMatrix() template from
 CullVisitor.cpp into include/osg/CullSettings to make it easier to implement
 custom clampProjectionMatrix callbacks

---
 include/osg/CullSettings    | 82 ++++++++++++++++++++++++++++++++++++
 src/osgUtil/CullVisitor.cpp | 84 +------------------------------------
 2 files changed, 84 insertions(+), 82 deletions(-)

diff --git a/include/osg/CullSettings b/include/osg/CullSettings
index c1a8877ce..c61fe9138 100644
--- a/include/osg/CullSettings
+++ b/include/osg/CullSettings
@@ -270,6 +270,88 @@ class OSG_EXPORT CullSettings
 
 };
 
+template<class matrix_type, class value_type>
+bool clampProjectionMatrix(matrix_type& projection, double& znear, double& zfar, value_type nearFarRatio)
+{
+    double epsilon = 1e-6;
+    if (zfar<znear-epsilon)
+    {
+        if (zfar != -FLT_MAX || znear != FLT_MAX)
+        {
+            OSG_INFO<<"_clampProjectionMatrix not applied, invalid depth range, znear = "<<znear<<"  zfar = "<<zfar<<std::endl;
+        }
+        return false;
+    }
+
+    if (zfar<znear+epsilon)
+    {
+        // znear and zfar are too close together and could cause divide by zero problems
+        // late on in the clamping code, so move the znear and zfar apart.
+        double average = (znear+zfar)*0.5;
+        znear = average-epsilon;
+        zfar = average+epsilon;
+        // OSG_INFO << "_clampProjectionMatrix widening znear and zfar to "<<znear<<" "<<zfar<<std::endl;
+    }
+
+    if (fabs(projection(0,3))<epsilon  && fabs(projection(1,3))<epsilon  && fabs(projection(2,3))<epsilon )
+    {
+        // OSG_INFO << "Orthographic matrix before clamping"<<projection<<std::endl;
+
+        value_type delta_span = (zfar-znear)*0.02;
+        if (delta_span<1.0) delta_span = 1.0;
+        value_type desired_znear = znear - delta_span;
+        value_type desired_zfar = zfar + delta_span;
+
+        // assign the clamped values back to the computed values.
+        znear = desired_znear;
+        zfar = desired_zfar;
+
+        projection(2,2)=-2.0f/(desired_zfar-desired_znear);
+        projection(3,2)=-(desired_zfar+desired_znear)/(desired_zfar-desired_znear);
+
+        // OSG_INFO << "Orthographic matrix after clamping "<<projection<<std::endl;
+    }
+    else
+    {
+
+        // OSG_INFO << "Persepective matrix before clamping"<<projection<<std::endl;
+
+        //std::cout << "_computed_znear"<<_computed_znear<<std::endl;
+        //std::cout << "_computed_zfar"<<_computed_zfar<<std::endl;
+
+        value_type zfarPushRatio = 1.02;
+        value_type znearPullRatio = 0.98;
+
+        //znearPullRatio = 0.99;
+
+        value_type desired_znear = znear * znearPullRatio;
+        value_type desired_zfar = zfar * zfarPushRatio;
+
+        // near plane clamping.
+        double min_near_plane = zfar*nearFarRatio;
+        if (desired_znear<min_near_plane) desired_znear=min_near_plane;
+
+        // assign the clamped values back to the computed values.
+        znear = desired_znear;
+        zfar = desired_zfar;
+
+        value_type trans_near_plane = (-desired_znear*projection(2,2)+projection(3,2))/(-desired_znear*projection(2,3)+projection(3,3));
+        value_type trans_far_plane = (-desired_zfar*projection(2,2)+projection(3,2))/(-desired_zfar*projection(2,3)+projection(3,3));
+
+        value_type ratio = fabs(2.0/(trans_near_plane-trans_far_plane));
+        value_type center = -(trans_near_plane+trans_far_plane)/2.0;
+
+        projection.postMult(osg::Matrix(1.0f,0.0f,0.0f,0.0f,
+                                        0.0f,1.0f,0.0f,0.0f,
+                                        0.0f,0.0f,ratio,0.0f,
+                                        0.0f,0.0f,center*ratio,1.0f));
+
+        // OSG_INFO << "Persepective matrix after clamping"<<projection<<std::endl;
+    }
+    return true;
+}
+
+
 
 }
 
diff --git a/src/osgUtil/CullVisitor.cpp b/src/osgUtil/CullVisitor.cpp
index d44f683e4..ce7e4a3fc 100644
--- a/src/osgUtil/CullVisitor.cpp
+++ b/src/osgUtil/CullVisitor.cpp
@@ -252,96 +252,16 @@ void CullVisitor::popProjectionMatrix()
     CullStack::popProjectionMatrix();
 }
 
-template<class matrix_type, class value_type>
-bool _clampProjectionMatrix(matrix_type& projection, double& znear, double& zfar, value_type nearFarRatio)
-{
-    double epsilon = 1e-6;
-    if (zfar<znear-epsilon)
-    {
-        if (zfar != -FLT_MAX || znear != FLT_MAX)
-        {
-            OSG_INFO<<"_clampProjectionMatrix not applied, invalid depth range, znear = "<<znear<<"  zfar = "<<zfar<<std::endl;
-        }
-        return false;
-    }
-
-    if (zfar<znear+epsilon)
-    {
-        // znear and zfar are too close together and could cause divide by zero problems
-        // late on in the clamping code, so move the znear and zfar apart.
-        double average = (znear+zfar)*0.5;
-        znear = average-epsilon;
-        zfar = average+epsilon;
-        // OSG_INFO << "_clampProjectionMatrix widening znear and zfar to "<<znear<<" "<<zfar<<std::endl;
-    }
-
-    if (fabs(projection(0,3))<epsilon  && fabs(projection(1,3))<epsilon  && fabs(projection(2,3))<epsilon )
-    {
-        // OSG_INFO << "Orthographic matrix before clamping"<<projection<<std::endl;
-
-        value_type delta_span = (zfar-znear)*0.02;
-        if (delta_span<1.0) delta_span = 1.0;
-        value_type desired_znear = znear - delta_span;
-        value_type desired_zfar = zfar + delta_span;
-
-        // assign the clamped values back to the computed values.
-        znear = desired_znear;
-        zfar = desired_zfar;
-
-        projection(2,2)=-2.0f/(desired_zfar-desired_znear);
-        projection(3,2)=-(desired_zfar+desired_znear)/(desired_zfar-desired_znear);
-
-        // OSG_INFO << "Orthographic matrix after clamping "<<projection<<std::endl;
-    }
-    else
-    {
-
-        // OSG_INFO << "Persepective matrix before clamping"<<projection<<std::endl;
-
-        //std::cout << "_computed_znear"<<_computed_znear<<std::endl;
-        //std::cout << "_computed_zfar"<<_computed_zfar<<std::endl;
-
-        value_type zfarPushRatio = 1.02;
-        value_type znearPullRatio = 0.98;
-
-        //znearPullRatio = 0.99;
-
-        value_type desired_znear = znear * znearPullRatio;
-        value_type desired_zfar = zfar * zfarPushRatio;
-
-        // near plane clamping.
-        double min_near_plane = zfar*nearFarRatio;
-        if (desired_znear<min_near_plane) desired_znear=min_near_plane;
-
-        // assign the clamped values back to the computed values.
-        znear = desired_znear;
-        zfar = desired_zfar;
-
-        value_type trans_near_plane = (-desired_znear*projection(2,2)+projection(3,2))/(-desired_znear*projection(2,3)+projection(3,3));
-        value_type trans_far_plane = (-desired_zfar*projection(2,2)+projection(3,2))/(-desired_zfar*projection(2,3)+projection(3,3));
-
-        value_type ratio = fabs(2.0/(trans_near_plane-trans_far_plane));
-        value_type center = -(trans_near_plane+trans_far_plane)/2.0;
-
-        projection.postMult(osg::Matrix(1.0f,0.0f,0.0f,0.0f,
-                                        0.0f,1.0f,0.0f,0.0f,
-                                        0.0f,0.0f,ratio,0.0f,
-                                        0.0f,0.0f,center*ratio,1.0f));
-
-        // OSG_INFO << "Persepective matrix after clamping"<<projection<<std::endl;
-    }
-    return true;
-}
 
 
 bool CullVisitor::clampProjectionMatrixImplementation(osg::Matrixf& projection, double& znear, double& zfar) const
 {
-    return _clampProjectionMatrix( projection, znear, zfar, _nearFarRatio );
+    return osg::clampProjectionMatrix( projection, znear, zfar, _nearFarRatio );
 }
 
 bool CullVisitor::clampProjectionMatrixImplementation(osg::Matrixd& projection, double& znear, double& zfar) const
 {
-    return _clampProjectionMatrix( projection, znear, zfar, _nearFarRatio );
+    return osg::clampProjectionMatrix( projection, znear, zfar, _nearFarRatio );
 }
 
 template<typename Comparator>