From 5d3f54edb2110da18beb7da7b66651541317e85f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vladim=C3=ADr=20Vondru=C5=A1?= <mosra@centrum.cz>
Date: Sun, 26 Feb 2012 15:22:33 +0100
Subject: [PATCH] Warn and assertion fail when mesh has no vertices/indexes
 before drawing.

---
 src/IndexedMesh.cpp | 12 ++++++++++++
 src/IndexedMesh.h   |  3 +++
 src/Mesh.cpp        |  7 +++++++
 src/Mesh.h          |  2 +-
 4 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/src/IndexedMesh.cpp b/src/IndexedMesh.cpp
index 4674427a1..240f547db 100644
--- a/src/IndexedMesh.cpp
+++ b/src/IndexedMesh.cpp
@@ -15,7 +15,10 @@
 
 #include "IndexedMesh.h"
 
+#include <cassert>
+
 using namespace std;
+using namespace Corrade::Utility;
 
 namespace Magnum {
 
@@ -48,4 +51,13 @@ void IndexedMesh::draw() {
         glDisableVertexAttribArray(*it);
 }
 
+void IndexedMesh::finalize() {
+    if(!_indexCount) {
+        Error() << "IndexedMesh: the mesh has zero index count!";
+        assert(0);
+    }
+
+    Mesh::finalize();
+}
+
 }
diff --git a/src/IndexedMesh.h b/src/IndexedMesh.h
index 9eb984fdc..a55422a10 100644
--- a/src/IndexedMesh.h
+++ b/src/IndexedMesh.h
@@ -76,6 +76,9 @@ class MAGNUM_EXPORT IndexedMesh: public Mesh {
          */
         void draw();
 
+    protected:
+        void finalize();
+
     private:
         Buffer _indexBuffer;
         GLsizei _indexCount;
diff --git a/src/Mesh.cpp b/src/Mesh.cpp
index 432372492..1030ad6a7 100644
--- a/src/Mesh.cpp
+++ b/src/Mesh.cpp
@@ -16,9 +16,11 @@
 #include "Mesh.h"
 #include "Buffer.h"
 
+#include <cassert>
 #include <iostream>
 
 using namespace std;
+using namespace Corrade::Utility;
 
 namespace Magnum {
 
@@ -68,6 +70,11 @@ void Mesh::finalize() {
     /* Already finalized */
     if(finalized) return;
 
+    if(!_vertexCount) {
+        Error() << "Mesh: the mesh has zero vertex count!";
+        assert(0);
+    }
+
     /* Finalize attribute positions for every buffer */
     for(map<Buffer*, pair<bool, vector<Attribute> > >::iterator it = _buffers.begin(); it != _buffers.end(); ++it) {
         /* Avoid confustion */
diff --git a/src/Mesh.h b/src/Mesh.h
index e97e0e7b4..5a2c83dc4 100644
--- a/src/Mesh.h
+++ b/src/Mesh.h
@@ -214,7 +214,7 @@ class MAGNUM_EXPORT Mesh {
          * Computes location and stride of each attribute in its buffer. After
          * this function is called, no new attribute can be bound.
          */
-        void finalize();
+        virtual void finalize();
 
         /**
          * @brief Set the mesh dirty