From a797253f7e2ad84dc3df7b14c11abbd33d0dd877 Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Wed, 27 Sep 2023 16:57:48 +0100
Subject: [PATCH] Added support to vsg::Builder for decorating created
 subgraphs with CullNode

---
 include/vsg/utils/Builder.h |  4 +++
 src/vsg/utils/Builder.cpp   | 54 ++++++++++++++++++++++++++++++++-----
 2 files changed, 51 insertions(+), 7 deletions(-)

diff --git a/include/vsg/utils/Builder.h b/include/vsg/utils/Builder.h
index 391632045..a816ed6fd 100644
--- a/include/vsg/utils/Builder.h
+++ b/include/vsg/utils/Builder.h
@@ -57,6 +57,9 @@ namespace vsg
         vec4 color = {1.0f, 1.0f, 1.0f, 1.0f};
         mat4 transform;
 
+        /// cullNode flag indicates whether a CullNode should decorate the creted subgraph
+        bool cullNode = false;
+
         template<typename T>
         void set(const t_box<T>& bb)
         {
@@ -122,6 +125,7 @@ namespace vsg
         ref_ptr<Data> instancePositions(const GeometryInfo& info, uint32_t& instanceCount);
         ref_ptr<Data> instanceColors(const GeometryInfo& info, uint32_t instanceCount);
         vec3 y_texcoord(const StateInfo& info) const;
+        ref_ptr<Node> decorateWithCullNodeIfRequired(const GeometryInfo& info, ref_ptr<Node> node) const;
 
         ref_ptr<ShaderSet> _flatShadedShaderSet;
         ref_ptr<ShaderSet> _phongShaderSet;
diff --git a/src/vsg/utils/Builder.cpp b/src/vsg/utils/Builder.cpp
index cb0db55c3..dc420730d 100644
--- a/src/vsg/utils/Builder.cpp
+++ b/src/vsg/utils/Builder.cpp
@@ -2,6 +2,7 @@
 #include <vsg/io/Logger.h>
 #include <vsg/io/read.h>
 #include <vsg/nodes/StateGroup.h>
+#include <vsg/nodes/CullNode.h>
 #include <vsg/nodes/VertexIndexDraw.h>
 #include <vsg/state/ColorBlendState.h>
 #include <vsg/state/DepthStencilState.h>
@@ -203,6 +204,45 @@ vec3 Builder::y_texcoord(const StateInfo& info) const
     }
 }
 
+ref_ptr<Node> Builder::decorateWithCullNodeIfRequired(const GeometryInfo& info, ref_ptr<Node> node) const
+{
+   if (info.cullNode)
+    {
+        auto cullNode = vsg::CullNode::create();
+        cullNode->child = node;
+
+        if (info.positions)
+        {
+            if (auto v3a = info.positions.cast<vec3Array>())
+            {
+                box bound;
+                for(auto& v : *v3a)
+                {
+                    bound.add(v);
+                }
+                cullNode->bound.center = (bound.min + bound.max) * 0.5f;
+                cullNode->bound.radius = vsg::length(bound.max - bound.min) * 0.5 + vsg::length(info.dx + info.dy + info.dz);
+            }
+            else
+            {
+                // unable to compute bound so do not decorate with a CullNode.
+                return node;
+            }
+        }
+        else
+        {
+            cullNode->bound.center = info.position;
+            cullNode->bound.radius = vsg::length(info.dx + info.dy + info.dz);
+        }
+
+        return cullNode;
+    }
+    else
+    {
+        return node;
+    }
+}
+
 ref_ptr<Node> Builder::createBox(const GeometryInfo& info, const StateInfo& stateInfo)
 {
     auto& subgraph = _boxes[info];
@@ -339,7 +379,7 @@ ref_ptr<Node> Builder::createBox(const GeometryInfo& info, const StateInfo& stat
 
     if (compileTraversal) compileTraversal->compile(scenegraph);
 
-    subgraph = scenegraph;
+    subgraph = decorateWithCullNodeIfRequired(info, scenegraph);
     return subgraph;
 }
 
@@ -568,7 +608,7 @@ ref_ptr<Node> Builder::createCapsule(const GeometryInfo& info, const StateInfo&
 
     if (compileTraversal) compileTraversal->compile(scenegraph);
 
-    subgraph = scenegraph;
+    subgraph = decorateWithCullNodeIfRequired(info, scenegraph);
     return subgraph;
 }
 
@@ -778,7 +818,7 @@ ref_ptr<Node> Builder::createCone(const GeometryInfo& info, const StateInfo& sta
 
     if (compileTraversal) compileTraversal->compile(scenegraph);
 
-    subgraph = scenegraph;
+    subgraph = decorateWithCullNodeIfRequired(info, scenegraph);
     return subgraph;
 }
 
@@ -1025,7 +1065,7 @@ ref_ptr<Node> Builder::createCylinder(const GeometryInfo& info, const StateInfo&
 
     if (compileTraversal) compileTraversal->compile(scenegraph);
 
-    subgraph = scenegraph;
+    subgraph = decorateWithCullNodeIfRequired(info, scenegraph);
     return subgraph;
 }
 
@@ -1128,7 +1168,7 @@ ref_ptr<Node> Builder::createDisk(const GeometryInfo& info, const StateInfo& sta
 
     if (compileTraversal) compileTraversal->compile(scenegraph);
 
-    subgraph = scenegraph;
+    subgraph = decorateWithCullNodeIfRequired(info, scenegraph);
     return subgraph;
 }
 
@@ -1317,7 +1357,7 @@ ref_ptr<Node> Builder::createSphere(const GeometryInfo& info, const StateInfo& s
 
     if (compileTraversal) compileTraversal->compile(scenegraph);
 
-    subgraph = scenegraph;
+    subgraph = decorateWithCullNodeIfRequired(info, scenegraph);
     return subgraph;
 }
 
@@ -1450,6 +1490,6 @@ ref_ptr<Node> Builder::createHeightField(const GeometryInfo& info, const StateIn
 
     if (compileTraversal) compileTraversal->compile(scenegraph);
 
-    subgraph = scenegraph;
+    subgraph = decorateWithCullNodeIfRequired(info, scenegraph);
     return subgraph;
 }