Generalize fixed-N Ngon List indexings

Author: devsh

include/nbl/asset/IPolygonGeometry.h

@@ -88,14 +88,17 @@ class IPolygonGeometryBase : public virtual core::IReferenceCounted
                 virtual uint8_t rate_impl() const = 0;
         };
         //
-        NBL_API2 static IIndexingCallback* PointList();
-        NBL_API2 static IIndexingCallback* LineList();
-        NBL_API2 static IIndexingCallback* TriangleList();
-        NBL_API2 static IIndexingCallback* QuadList();
+        static inline IIndexingCallback* PointList() {return NGonList(1);}
+        static inline IIndexingCallback* LineList() {return NGonList(2);}
+        static inline IIndexingCallback* TriangleList() {return NGonList(3);}
+        static inline IIndexingCallback* QuadList() {return NGonList(4);}
+        //
+        NBL_API2 static IIndexingCallback* NGonList(const uint8_t n);
         // TODO: Adjacency, Patch, etc.
         NBL_API2 static IIndexingCallback* TriangleStrip();
         NBL_API2 static IIndexingCallback* TriangleFan();
 
+
         // This should be a pointer to a stateless singleton (think of it more like a dynamic enum/template than anything else)
         inline const IIndexingCallback* getIndexingCallback() const {return m_indexing;}
 

src/nbl/asset/ICPUPolygonGeometry.cpp

@@ -39,25 +39,20 @@ class CListIndexingCB final : public IPolygonGeometryBase::IIndexingCallback
             }
         }
 };
-auto IPolygonGeometryBase::PointList() -> IIndexingCallback*
+#include <boost/preprocessor/arithmetic/add.hpp>
+auto IPolygonGeometryBase::NGonList(const uint8_t n)-> IIndexingCallback*
 {
-    static CListIndexingCB<1> singleton;
-    return &singleton;
-}
-auto IPolygonGeometryBase::LineList() -> IIndexingCallback*
-{
-    static CListIndexingCB<2> singleton;
-    return &singleton;
-}
-auto IPolygonGeometryBase::TriangleList() -> IIndexingCallback*
-{
-    static CListIndexingCB<3> singleton;
-    return &singleton;
-}
-auto IPolygonGeometryBase::QuadList() -> IIndexingCallback*
-{
-    static CListIndexingCB<4> singleton;
-    return &singleton;
+#define DECL(z, n, text) text<n+1> singleton_ ## n;
+    BOOST_PP_REPEAT(255,DECL,static CListIndexingCB)
+#undef DECL
+    switch (n)
+    {
+#define CASE(z, n, text) text BOOST_PP_ADD(n,1): return &singleton_ ## n;
+        BOOST_PP_REPEAT(255,CASE,case)
+#undef CASE
+        default:
+            return nullptr;
+    }
 }
 
 class CTriangleStripIndexingCB final : public IPolygonGeometryBase::IIndexingCallback