diff --git a/CMakeLists.txt b/CMakeLists.txt
index e374de9..e26d76b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -108,6 +108,7 @@ target_compile_features(${PROJECT_NAME}
 
 target_compile_definitions(${PROJECT_NAME}
 	PRIVATE ${PNG_DEFINITIONS}
+	PRIVATE VWR_WITH_IMPLICIT_CONVERSIONS=1
 )
 
 configure_file(src/${PROJECT_NAME}Config.h.in ${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}Config.h)
diff --git a/lib/vectorwrapper b/lib/vectorwrapper
index 736e838..2f4d319 160000
--- a/lib/vectorwrapper
+++ b/lib/vectorwrapper
@@ -1 +1 @@
-Subproject commit 736e83893a645cce2cc0767237f538785cf8651d
+Subproject commit 2f4d31967541c9c4a87b2511fb0c6d3792c72c2d
diff --git a/src/gamescenebase.cpp b/src/gamescenebase.cpp
index df01248..471a79d 100644
--- a/src/gamescenebase.cpp
+++ b/src/gamescenebase.cpp
@@ -8,9 +8,23 @@
 #include <SDL2/SDL.h>
 #include <algorithm>
 #include <ciso646>
+#if !defined(NDEBUG)
+#	include "compatibility.h"
+#	include <cmath>
+#	include <limits>
+#endif
 
 namespace curry {
 	namespace {
+#if !defined(NDEBUG)
+		bool are_equal_rel (float parA, float parB, float parEpsilon) a_pure;
+
+		//see: http://stackoverflow.com/questions/4548004/how-to-correctly-and-standardly-compare-floats
+		bool are_equal_rel (float parA, float parB, float parEpsilon) {
+			return (std::fabs(parA - parB) <= parEpsilon * std::max(std::fabs(parA), std::fabs(parB)));
+		}
+#endif
+
 		///---------------------------------------------------------------------
 		///---------------------------------------------------------------------
 		bool DoEvents (cloonel::InputBag& parInput, cloonel::SDLMain* parSdlMain) {
@@ -52,6 +66,7 @@ namespace curry {
 		///----------------------------------------------------------------------
 		bool clip_rect (Rect<float>& parSrc, Rect<float>& parDest, const Rect<float>& parClip) {
 			typedef Rect<float> RectFloat;
+			assert(are_equal_rel(parSrc.width(), parDest.width(), std::numeric_limits<float>::epsilon()));
 			assert(parSrc.is_valid());
 			assert(parDest.is_valid());
 
@@ -60,29 +75,34 @@ namespace curry {
 			if (parDest.to <= parClip.from or parDest.from >= parClip.to)
 				return false;
 
-			{
-				const RectFloat clip(vec2f(0.0f), vec2f(1.0f));
-				const vec2f srcWidthHeight(parSrc.width_height());
-				const vec2f scaledOffs((parDest.from - parClip.from) / parClip.width_height());
-				parSrc.from -= vec2f(std::min(0.0f, scaledOffs.x() * srcWidthHeight.x()), std::min(0.0f, scaledOffs.y() * srcWidthHeight.y()));
-				const vec2f scaledCrop((parClip.to - parDest.to) / parClip.width_height());
-				parSrc.to += vec2f(std::min(0.0f, scaledCrop.x() * srcWidthHeight.x()), std::min(0.0f, scaledCrop.y() * srcWidthHeight.y()));
-				assert(parSrc.is_valid());
-			}
-
-			RectFloat dst(parDest.from - parClip.from, parDest.to - parClip.from);
-			dst.from.x() = std::max(dst.from.x(), parClip.from.x());
-			dst.from.y() = std::max(dst.from.y(), parClip.from.y());
-			dst.to.x() = std::min(dst.to.x(), parClip.to.x());
-			dst.to.y() = std::min(dst.to.y(), parClip.to.y());
+			RectFloat dst;
+			dst.from.x() = std::max(parDest.from.x(), parClip.from.x());
+			dst.from.y() = std::max(parDest.from.y(), parClip.from.y());
+			dst.to.x() = std::min(parDest.to.x(), parClip.to.x());
+			dst.to.y() = std::min(parDest.to.y(), parClip.to.y());
 
 			if (not dst.is_valid())
 				return false;
 
-			parDest.from += parClip.from;
-			parDest.to += parClip.from;
+			assert(parDest.from <= dst.from);
+			assert(parDest.to >= dst.to);
 
-			assert(parDest.is_valid());
+			RectFloat src;
+			{
+				const vec2f srcWidthHeight(parSrc.width_height());
+				const vec2f scaledOffs((dst.from - parDest.from) / parDest.width_height());
+				src.from = parSrc.from + scaledOffs * srcWidthHeight;
+				const vec2f scaledCrop((parDest.to - dst.to) / parDest.width_height());
+				src.to = parSrc.to - scaledCrop * srcWidthHeight;
+				assert(src.is_valid());
+
+				assert(dst.is_valid());
+				assert(dst.from >= parClip.from);
+				assert(dst.to <= parClip.to);
+				assert(are_equal_rel(src.width(), dst.width(), std::numeric_limits<float>::epsilon()));
+			}
+			parDest = dst;
+			parSrc = src;
 			return true;
 		}
 	} //unnamed namespace
@@ -149,6 +169,8 @@ namespace curry {
 
 		auto src = make_sdlrect(parSrc);
 		auto dst = make_sdlrect(parDest);
+		assert(src.w == dst.w);
+		assert(src.h == dst.h);
 		SDL_RenderCopy(m_sdlmain->GetRenderer(), parTexture.texture(), &src, &dst);
 	}
 } //namespace curry
diff --git a/src/rect.hpp b/src/rect.hpp
index 126c5aa..66e949d 100644
--- a/src/rect.hpp
+++ b/src/rect.hpp
@@ -11,6 +11,7 @@ namespace curry {
 	public:
 		typedef vwr::Vec<std::array<T, 2>> VecType;
 
+		Rect() = default;
 		Rect (T parLeft, T parTop, T parRight, T parBottom);
 		template <typename V1, typename V2>
 		Rect (const vwr::Vec<V1>& parLeftTop, const vwr::Vec<V2>& parBottomRight);