Don't register platforms that have gone out from the bottom.

This fixes the assert occurring after a few seconds playing.

src/platformset.cpp

@@ -29,6 +29,18 @@
 #include <algorithm>
 
 namespace cloonel {
+	namespace {
+		///----------------------------------------------------------------------
+		///----------------------------------------------------------------------
+		boost::circular_buffer<Platform>::const_iterator FindFirstVisible (const boost::circular_buffer<Platform>& parPlatforms) {
+			auto curr = parPlatforms.begin();
+			while (curr != parPlatforms.end() and curr->TopLeft().y() < 0.0f) {
+				++curr;
+			}
+			return curr;
+		}
+	} //unnamed namespace
+
 	///--------------------------------------------------------------------------
 	///--------------------------------------------------------------------------
 	PlatformSet::PlatformSet (SDLMain* parSdl) :
@@ -52,18 +64,24 @@ namespace cloonel {
 	///--------------------------------------------------------------------------
 	///--------------------------------------------------------------------------
 	void PlatformSet::CopyBars (std::vector<const HorzCollisionBar*>& parOut) const {
-		parOut.reserve(parOut.size() + m_platforms.size());
+		auto eleCopy = FindFirstVisible(m_platforms);
-		for (auto& platf : m_platforms) {
+		const size_t count = m_platforms.end() - eleCopy;
-			parOut.push_back(platf.TopCollisionBar());
+		parOut.reserve(parOut.size() + count);
+		while (m_platforms.end() != eleCopy) {
+			parOut.push_back(eleCopy->TopCollisionBar());
+			++eleCopy;
 		}
 	}
 
 	///--------------------------------------------------------------------------
 	///--------------------------------------------------------------------------
 	void PlatformSet::CopyDrawables (std::vector<const Drawable*>& parOut) const {
-		parOut.reserve(parOut.size() + m_platforms.size());
+		auto eleCopy = FindFirstVisible(m_platforms);
-		for (auto& platf : m_platforms) {
+		const size_t count = m_platforms.end() - eleCopy;
-			parOut.push_back(&platf);
+		parOut.reserve(parOut.size() + count);
+		while (m_platforms.end() != eleCopy) {
+			parOut.push_back(&*eleCopy);
+			++eleCopy;
 		}
 	}