From 3edcb212fe311f9eb61a188b94219e1dc158fb7e Mon Sep 17 00:00:00 2001
From: Glenn Waldron <gwaldron@gmail.com>
Date: Mon, 20 Nov 2023 14:17:59 -0500
Subject: [PATCH] disable GPU culling on the NVGL path for FMG and XMG, for
 better performance and no artifacts

---
 src/osgEarth/Chonk.cpp             | 2 ++
 src/osgEarth/Chonk.glsl            | 6 +++---
 src/osgEarth/FeatureModelGraph.cpp | 5 +++++
 src/osgEarth/XYZModelGraph.cpp     | 4 ++++
 tests/viewpoints.xml               | 9 +++++++++
 5 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/src/osgEarth/Chonk.cpp b/src/osgEarth/Chonk.cpp
index 6353531cee..3eac9b318f 100644
--- a/src/osgEarth/Chonk.cpp
+++ b/src/osgEarth/Chonk.cpp
@@ -1275,6 +1275,8 @@ ChonkDrawable::GLObjects::draw(osg::State& state)
     else
         _instanceInputBuf->bindBufferBase(0);
 
+    _ext->glMemoryBarrier(GL_SHADER_STORAGE_BARRIER_BIT); // ...maybe
+
     GLenum elementType = sizeof(Chonk::element_t) == sizeof(GLushort) ?
         GL_UNSIGNED_SHORT :
         GL_UNSIGNED_INT;
diff --git a/src/osgEarth/Chonk.glsl b/src/osgEarth/Chonk.glsl
index 9640d6ac85..215de67867 100644
--- a/src/osgEarth/Chonk.glsl
+++ b/src/osgEarth/Chonk.glsl
@@ -195,9 +195,9 @@ void oe_chonk_default_fragment(inout vec4 color)
 
     // apply the high fade from the instancer
     if (oe_fade <= 1.0) color.a *= oe_fade;
-    else if (oe_fade <= 2.0) color.rgb = vec3(1, 0, 0);
-    else if (oe_fade <= 3.0) color.rgb = vec3(1, 1, 0);
-    else if (oe_fade <= 4.0) color.rgb = vec3(0, 1, 0);
+    else if (oe_fade <= 2.0) color.rgb = vec3(1, 0, 0); // REASON_FRUSTUM
+    else if (oe_fade <= 3.0) color.rgb = vec3(1, 1, 0); // REASON_SSE
+    else if (oe_fade <= 4.0) color.rgb = vec3(0, 1, 0); // REASON_NEARCLIP
     else color.rgb = vec3(1, 0, 1); // should never happen :)
 
 #elif defined(OE_USE_ALPHA_TO_COVERAGE)
diff --git a/src/osgEarth/FeatureModelGraph.cpp b/src/osgEarth/FeatureModelGraph.cpp
index a110f11275..e64519baab 100644
--- a/src/osgEarth/FeatureModelGraph.cpp
+++ b/src/osgEarth/FeatureModelGraph.cpp
@@ -1758,8 +1758,13 @@ FeatureModelGraph::createOrUpdateNode(FeatureCursor*           cursor,
                 _texturesCache, _texturesCacheMutex));
 
         osg::ref_ptr<ChonkDrawable> drawable = new ChonkDrawable();
+        
+        // culling by osg tile will be sufficient here.
+        drawable->setUseGPUCulling(false);
+
         if (xform)
         {
+
             for (unsigned i = 0; i < xform->getNumChildren(); ++i)
             {
                 drawable->add(xform->getChild(i), factory);
diff --git a/src/osgEarth/XYZModelGraph.cpp b/src/osgEarth/XYZModelGraph.cpp
index 382e6b9471..d8dbc37a28 100644
--- a/src/osgEarth/XYZModelGraph.cpp
+++ b/src/osgEarth/XYZModelGraph.cpp
@@ -148,6 +148,10 @@ XYZModelGraph::createNode(const TileKey& key, ProgressCallback* progress)
                     _texturesCache, _texturesCacheMutex));
 
             osg::ref_ptr<ChonkDrawable> drawable = new ChonkDrawable();
+            
+            // culling by osg tile will be sufficient here.
+            drawable->setUseGPUCulling(false);
+
             if (xform)
             {
                 for (unsigned i = 0; i < xform->getNumChildren(); ++i)
diff --git a/tests/viewpoints.xml b/tests/viewpoints.xml
index 964e30d260..10ae96eb4d 100644
--- a/tests/viewpoints.xml
+++ b/tests/viewpoints.xml
@@ -129,4 +129,13 @@
         <height>-12.0398843260482</height>
         <srs>+proj=longlat +datum=WGS84 +no_defs</srs>
     </viewpoint>
+    <viewpoint name="Toronto">
+        <heading>0.109355</heading>
+        <pitch>-20.3288</pitch>
+        <range>4697.58m</range>
+        <long>-79.3900928274749</long>
+        <lat>43.65526709145713</lat>
+        <height>72.19622826110572</height>
+        <srs>+proj=longlat +datum=WGS84 +no_defs</srs>
+    </viewpoint>
 </viewpoints>