fix static index buffer issue more than 1 box

hw3d/Box.cpp

@@ -92,6 +92,10 @@ Box::Box( Graphics& gfx,
 
 		AddStaticBind( std::make_unique<Topology>( gfx,D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST ) );
 	}
+	else
+	{
+		SetIndexFromStatic();
+	}
 
 	AddBind( std::make_unique<TransformCbuf>( gfx,*this ) );
 }

hw3d/DrawableBase.h

@@ -17,10 +17,23 @@ public:
 	}
 	void AddStaticIndexBuffer( std::unique_ptr<IndexBuffer> ibuf ) noexcept(!IS_DEBUG)
 	{
-		assert( pIndexBuffer == nullptr );
+		assert( "Attempting to add index buffer a second time" && pIndexBuffer == nullptr );
 		pIndexBuffer = ibuf.get();
 		staticBinds.push_back( std::move( ibuf ) );
 	}
+	void SetIndexFromStatic() noexcept(!IS_DEBUG)
+	{
+		assert( "Attempting to add index buffer a second time" && pIndexBuffer == nullptr );
+		for( const auto& b : staticBinds )
+		{
+			if( const auto p = dynamic_cast<IndexBuffer*>(b.get()) )
+			{
+				pIndexBuffer = p;
+				return;
+			}
+		}
+		assert( "Failed to find index buffer in static binds" && pIndexBuffer != nullptr );
+	}
 private:
 	const std::vector<std::unique_ptr<Bindable>>& GetStaticBinds() const noexcept override
 	{