From c23d4a838596a2286ec04635f17ae87f64e4a108 Mon Sep 17 00:00:00 2001
From: Laurent Gomila <laurent.gom@gmail.com>
Date: Sat, 6 Jul 2013 18:24:30 +0200
Subject: [PATCH] Checking errors in RenderTarget::pushGLStates() to avoid
 generating false error messages when user leaves unchecked OpenGL errors
 (#340)

---
 src/SFML/Graphics/RenderTarget.cpp | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/SFML/Graphics/RenderTarget.cpp b/src/SFML/Graphics/RenderTarget.cpp
index 9394214ba..a2316cf0c 100644
--- a/src/SFML/Graphics/RenderTarget.cpp
+++ b/src/SFML/Graphics/RenderTarget.cpp
@@ -31,6 +31,7 @@
 #include <SFML/Graphics/Texture.hpp>
 #include <SFML/Graphics/VertexArray.hpp>
 #include <SFML/Graphics/GLCheck.hpp>
+#include <SFML/System/Err.hpp>
 #include <iostream>
 
 
@@ -242,6 +243,17 @@ void RenderTarget::pushGLStates()
 {
     if (activate(true))
     {
+#ifdef SFML_DEBUG
+        // make sure that the user didn't leave an unchecked OpenGL error
+        GLenum error = glGetError();
+        if (error != GL_NO_ERROR)
+        {
+            err() << "OpenGL error (" << error << ") detected in user code, "
+                  << "you should check for errors with glGetError()"
+                  << std::endl;
+        }
+#endif
+
         glCheck(glPushClientAttrib(GL_CLIENT_ALL_ATTRIB_BITS));
         glCheck(glPushAttrib(GL_ALL_ATTRIB_BITS));
         glCheck(glMatrixMode(GL_MODELVIEW));