add basic entity movement

src/td/simulation/system/EntityMove.cpp

@@ -1,11 +1,61 @@
+#include <td/Maths.h>
+#include <td/Types.h>
+#include <td/game/WorldTypes.h>
 #include <td/simulation/system/EntityMove.h>
 
+#include <td/game/World.h>
+
 namespace td {
 namespace sim {
 
+static Vec2i GetUnitDirection(Direction a_Direction) {
+	switch (a_Direction) {
+		case Direction::PositiveX:
+			return {1, 0};
+		case Direction::NegativeX:
+			return {-1, 0};
+		case Direction::PositiveY:
+			return {0, 1};
+		case Direction::NegativeY:
+			return {0, -1};
+	}
+	return {0, 0};
+}
+
+class DirectionTileVisitor : public game::TileHandler {
+  private:
+	Direction m_Direction;
+
+  public:
+	DirectionTileVisitor() {}
+
+	virtual void Handle(const game::EmptyTile& a_Tile) override {}
+
+	virtual void Handle(const game::TowerTile& a_Tile) override {}
+
+	virtual void Handle(const game::DecorationTile& a_Tile) override {}
+
+	virtual void Handle(const game::WalkableTile& a_Tile) override {
+		m_Direction = a_Tile->m_Direction;
+	}
+
+	const Direction GetDirection() {
+		return m_Direction;
+	}
+};
+
 void EntityMove::Tick(const game::World& a_World, WorldSnapshot& a_State, FpFloat a_Delta) {
 	for (auto& mob : a_State.m_Mobs) {
-		mob->m_Position.x += a_Delta;
+		auto tile = a_World.GetTile(static_cast<std::int32_t>(mob->m_Position.x), static_cast<std::int32_t>(mob->m_Position.y));
+		Direction direction = mob->m_Direction;
+		if (tile) {
+			DirectionTileVisitor visitor;
+			tile->Dispatch(visitor);
+			direction = visitor.GetDirection();
+		}
+		auto directVector = GetUnitDirection(direction);
+		mob->m_Position.x += directVector.x * a_Delta;
+		mob->m_Position.y += directVector.y * a_Delta;
 	}
 }