Don't move the viewport if it would generate gaps in the map.

In other words, don't let the player see past the end of the world.

src/ingamescene.cpp

@@ -69,6 +69,8 @@ namespace curry {
 #if !defined(NDEBUG)
 		std::cout << "World size set to " << world_size << '\n';
 #endif
+
+		m_local_data->viewport.allow_overscan(false);
 	}
 
 	void IngameScene::on_update (float parDeltaT) {
@@ -80,14 +82,16 @@ namespace curry {
 
 		auto& viewport = m_local_data->viewport;
 		const float speed = parDeltaT * speed_per_sec;
+		vec2f offset(0.0f);
 		if (cloonel::IsPressed(input_bag(), ActionRight))
-			viewport.set_position(viewport.position() + vec2f(speed, 0));
+			offset.x() += speed;
 		if (cloonel::IsPressed(input_bag(), ActionLeft))
-			viewport.set_position(viewport.position() - vec2f(speed, 0));
+			offset.x() -= speed;
 		if (cloonel::IsPressed(input_bag(), ActionUp))
-			viewport.set_position(viewport.position() - vec2f(0, speed));
+			offset.y() -= speed;
 		if (cloonel::IsPressed(input_bag(), ActionDown))
-			viewport.set_position(viewport.position() + vec2f(0, speed));
+			offset.y() += speed;
+		viewport.set_position(viewport.position() + offset);
 
 		const auto tilesize(static_cast<vec2f>(world.tile_size()));
 		const auto tilecount(m_local_data->worldtiles.width_height() / world.tile_size());

src/worldviewport.cpp

@@ -46,10 +46,21 @@ namespace curry {
 	}
 
 	void WorldViewport::set_position (const vec2f& parPos) {
-		m_position = parPos; //TODO: assert validity
+		if (m_allow_overscan) {
+			m_position = parPos;
+		}
+		else {
+			const auto max_offs = vector_cast<vec2f>(world_size_pixel(*m_world)) - size();
+			m_position.x() = std::min(std::max(parPos.x(), 0.0f), max_offs.x());
+			m_position.y() = std::min(std::max(parPos.y(), 0.0f), max_offs.y());
+		}
 	}
 
 	const TileIndex* WorldViewport::tile (const vec2us& parIndex) const {
 		return world()->tile(parIndex + starting_index(*this));
 	}
+
+	void WorldViewport::allow_overscan (bool parAllow) {
+		m_allow_overscan = parAllow;
+	}
 } //namespace curry

src/worldviewport.hpp

@@ -16,6 +16,7 @@ namespace curry {
 		const vec2f& position() const;
 		const vec2f& size() const;
 		const TileIndex* tile (const vec2us& parIndex) const;
+		void allow_overscan (bool parAllow);
 
 		void set_position (const vec2f& parPos);
 
@@ -26,5 +27,6 @@ namespace curry {
 		vec2f m_position;
 		vec2f m_size;
 		WorldGrid* m_world;
+		bool m_allow_overscan;
 	};
 } //namespace curry