add a bool parameter to allow forced reindexation of a mesh

include/osgUtil/MeshOptimizers

@@ -46,11 +46,16 @@ class OSGUTIL_EXPORT IndexMeshVisitor : public GeometryCollector
 {
 public:
     IndexMeshVisitor(Optimizer* optimizer = 0)
-        : GeometryCollector(optimizer, Optimizer::INDEX_MESH)
+        : GeometryCollector(optimizer, Optimizer::INDEX_MESH), _isForcedReindexationEnable(false)
     {
     }
+    inline void setGenerateNewIndicesOnAllGeometries(bool b) { _isForcedReindexationEnable = b; }
+    inline bool getGenerateNewIndicesOnAllGeometries() const { return _isForcedReindexationEnable; }
+
     void makeMesh(osg::Geometry& geom);
     void makeMesh();
+protected:
+    bool _isForcedReindexationEnable;
 };
 
 // Optimize the triangle order in a mesh for best use of the GPU's

src/osgUtil/MeshOptimizers.cpp

@@ -262,7 +262,7 @@ void IndexMeshVisitor::makeMesh(Geometry& geom)
     }
 
     // nothing to index
-    if (!numSurfacePrimitives || !numNonIndexedPrimitives) return;
+    if (!numSurfacePrimitives || (!_isForcedReindexationEnable && !numNonIndexedPrimitives)) return;
 
     // duplicate shared arrays as it isn't safe to rearrange vertices when arrays are shared.
     if (geom.containsSharedArrays()) geom.duplicateSharedArrays();