From 5957c2108202cbc7f8d446593f07d787a6b87881 Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Thu, 4 Jul 2002 09:49:12 +0000
Subject: [PATCH] Fixed the TriangleFunctor QUAD_STRIP code so that it produces
 consistent results.

---
 include/osg/Drawable                  |  8 +++---
 src/Demos/osggeometry/osggeometry.cpp | 37 +++++++++++++++++++++++++--
 2 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/include/osg/Drawable b/include/osg/Drawable
index 4b1a0ce9d..36544d260 100644
--- a/include/osg/Drawable
+++ b/include/osg/Drawable
@@ -435,7 +435,7 @@ public:
                 for(GLsizei i=3;i<count;i+=2,vptr+=2)
                 {
                     operator()(*(vptr),*(vptr+1),*(vptr+2));
-                    operator()(*(vptr),*(vptr+2),*(vptr+3));
+                    operator()(*(vptr+1),*(vptr+3),*(vptr+2));
                 }
                 break;
             }
@@ -501,7 +501,7 @@ public:
                 for(GLsizei i=3;i<count;i+=2,iptr+=2)
                 {
                     operator()(_vertexArrayPtr[*(iptr)],_vertexArrayPtr[*(iptr+1)],_vertexArrayPtr[*(iptr+2)]);
-                    operator()(_vertexArrayPtr[*(iptr)],_vertexArrayPtr[*(iptr+2)],_vertexArrayPtr[*(iptr+3)]);
+                    operator()(_vertexArrayPtr[*(iptr+1)],_vertexArrayPtr[*(iptr+3)],_vertexArrayPtr[*(iptr+2)]);
                 }
                 break;
             }
@@ -570,7 +570,7 @@ public:
                 for(GLsizei i=3;i<count;i+=2,iptr+=2)
                 {
                     operator()(_vertexArrayPtr[*(iptr)],_vertexArrayPtr[*(iptr+1)],_vertexArrayPtr[*(iptr+2)]);
-                    operator()(_vertexArrayPtr[*(iptr)],_vertexArrayPtr[*(iptr+2)],_vertexArrayPtr[*(iptr+3)]);
+                    operator()(_vertexArrayPtr[*(iptr+1)],_vertexArrayPtr[*(iptr+3)],_vertexArrayPtr[*(iptr+2)]);
                 }
                 break;
             }
@@ -637,7 +637,7 @@ public:
                 for(GLsizei i=3;i<count;i+=2,iptr+=2)
                 {
                     operator()(_vertexArrayPtr[*(iptr)],_vertexArrayPtr[*(iptr+1)],_vertexArrayPtr[*(iptr+2)]);
-                    operator()(_vertexArrayPtr[*(iptr)],_vertexArrayPtr[*(iptr+2)],_vertexArrayPtr[*(iptr+3)]);
+                    operator()(_vertexArrayPtr[*(iptr+1)],_vertexArrayPtr[*(iptr+3)],_vertexArrayPtr[*(iptr+2)]);
                 }
                 break;
             }
diff --git a/src/Demos/osggeometry/osggeometry.cpp b/src/Demos/osggeometry/osggeometry.cpp
index d9d452bb7..4317e29b0 100644
--- a/src/Demos/osggeometry/osggeometry.cpp
+++ b/src/Demos/osggeometry/osggeometry.cpp
@@ -35,6 +35,29 @@
 // with the various primitives in it, and the main() which sets up a basic viewer window and
 // adds to the it the scene generated by createScene().
 
+
+struct NormalPrint
+{
+    void operator() (const osg::Vec3& v1,const osg::Vec3& v2,const osg::Vec3& v3) const 
+    {
+        osg::Vec3 normal = (v2-v1)^(v3-v2);
+        normal.normalize();
+        std::cout << "\t("<<v1<<") ("<<v2<<") ("<<v3<<") "<<") normal ("<<normal<<")"<<std::endl;
+    }
+};
+
+// decompose Drawable primtives into triangles, print out these triangles and computed normals.
+void printTriangles(const std::string& name, osg::Drawable& drawable)
+{
+    std::cout<<name<<std::endl;
+    
+    osg::TriangleFunctor<NormalPrint> tf;
+    drawable.applyPrimitiveOperation(tf);
+ 
+    std::cout<<std::endl;
+}
+
+
 osg::Node* createScene()
 {
     // create the Geode (Geometry Node) to contain all our osg::Geometry objects.
@@ -299,7 +322,8 @@ osg::Node* createScene()
         // This time we simply use primitive, and hardwire the number of coords to use 
         // since we know up front,
         polyGeom->addPrimitive(new osg::DrawArrays(osg::Primitive::POLYGON,0,numCoords));
-        
+
+        printTriangles("Polygon",*polyGeom);
         
         // add the points geomtry to the geode.
         geode->addDrawable(polyGeom);
@@ -347,6 +371,8 @@ osg::Node* createScene()
         polyGeom->addPrimitive(new osg::DrawArrays(osg::Primitive::QUADS,0,numCoords));
         
         
+        printTriangles("Quads",*polyGeom);
+
         // add the points geomtry to the geode.
         geode->addDrawable(polyGeom);
     }
@@ -394,6 +420,8 @@ osg::Node* createScene()
         polyGeom->addPrimitive(new osg::DrawArrays(osg::Primitive::QUAD_STRIP,0,numCoords));
         
         
+        printTriangles("Quads strip",*polyGeom);
+
         // add the points geomtry to the geode.
         geode->addDrawable(polyGeom);
     }
@@ -462,6 +490,8 @@ osg::Node* createScene()
         polyGeom->addPrimitive(new osg::DrawArrays(osg::Primitive::TRIANGLE_FAN,12,5));
         
         
+        printTriangles("Triangles/Strip/Fan",*polyGeom);
+
         // add the points geomtry to the geode.
         geode->addDrawable(polyGeom);
     }
@@ -568,7 +598,7 @@ osg::Node* createBackground()
     // contains unsigned char indicies, UShortDrawElements which contains unsigned short indices,
     // and UIntDrawElements whcih contains ... unsigned int indices.  
     // The first parameter to DrawElements is 
-    polyGeom->addPrimitive(new osg::UShortDrawElements(osg::Primitive::QUADS,4,myIndices));
+    polyGeom->addPrimitive(new osg::UShortDrawElements(osg::Primitive::QUADS,numIndices,myIndices));
 
     // new we need to add the texture to the Drawable, we do so by creating a 
     // StateSet to contain the Texture StateAttribute.
@@ -600,6 +630,9 @@ osg::Node* createBackground()
     return transform;
 }
 
+
+
+
 int main( int argc, char **argv )
 {