Implement ghost movements

lib/Blinky.cpp

@@ -1,4 +1,5 @@
 #include "Blinky.hpp"
+#include "GameState.hpp"
 
 namespace pacman {
 
@@ -22,7 +23,7 @@ Position Blinky::target(const GameState & gameState) const {
   if (isInPen())
     return penDoorPosition();
 
-  return scatterTarget();
+  return state == State::Chase ? gridPositionToPosition(gameState.pacMan.positionInGrid()) : scatterTarget();
 }
 
 Position Blinky::initialPosition() const {

lib/Clyde.cpp

@@ -1,4 +1,5 @@
 #include "Clyde.hpp"
+#include "GameState.hpp"
 
 namespace pacman {
 
@@ -22,7 +23,15 @@ Position Clyde::target(const GameState & gameState) const {
   if (isInPen())
     return penDoorPosition();
 
-  return scatterTarget();
+  // Clyde always target its scatter target, unless pacman is further than 8 tiles away
+  auto targetPosition = scatterTarget();
+
+  const auto & pacmanPosition = gameState.pacMan.positionInGrid();
+  auto distanceFomPacMan = std::hypot(pos.x - pacmanPosition.x, pos.y - pacmanPosition.y);
+  if (state == State::Chase && distanceFomPacMan > 8)
+    targetPosition = gridPositionToPosition(pacmanPosition);
+
+  return targetPosition;
 }
 
 Position Clyde::initialPosition() const {

lib/Ghost.cpp

@@ -1,6 +1,7 @@
 #include "Ghost.hpp"
 #include <array>
 #include <cmath>
+#include <numeric>
 
 namespace pacman {
 
@@ -13,7 +14,7 @@ void Ghost::frighten() {
     return;
   direction = oppositeDirection(direction);
   state = State::Frightened;
-  timeFrighten = 0;
+  timeFrighten = {};
 }
 
 bool Ghost::isFrightened() const {
@@ -29,15 +30,15 @@ void Ghost::die() {
     return;
   direction = oppositeDirection(direction);
   state = State::Eyes;
-  timeFrighten = 0;
-  timeChase = 0;
+  timeFrighten = {};
+  timeChase = {};
 }
 
 void Ghost::reset() {
   pos = initialPosition();
   state = State::Scatter;
-  timeFrighten = 0;
-  timeChase = 0;
+  timeFrighten = {};
+  timeChase = {};
 }
 
 [[nodiscard]] GridPosition Ghost::currentSprite() const {
@@ -47,7 +48,7 @@ void Ghost::reset() {
     case State::Eyes:
       return Atlas::eyeSprite(direction);
     case State::Frightened:
-      if (timeFrighten < 3500)
+      if (timeFrighten.count() < 3500)
         return Atlas::initialFrightened(animationIndex);
       else
         return Atlas::endingFrightened(animationIndex);
@@ -67,11 +68,20 @@ void Ghost::update(std::chrono::milliseconds time_delta, const GameState & gameS
     state = State::Scatter;
 
   if (state == State::Frightened) {
-    timeFrighten += time_delta.count();
-    if (timeFrighten > 6000)
+    timeFrighten += time_delta;
+    if (timeFrighten.count() > 6000)
       state = State::Scatter;
   }
 
+  if (state == State::Scatter || state == State::Chase) {
+    timeChase += time_delta;
+    auto newState = defaultStateAtDuration(std::chrono::duration_cast<std::chrono::seconds>(timeChase));
+    if (newState != state) {
+      direction = oppositeDirection(direction);
+      state = newState;
+    }
+  }
+
   updateAnimation(time_delta);
   updatePosition(time_delta, gameState);
 }
@@ -105,6 +115,10 @@ void Ghost::updatePosition(std::chrono::milliseconds time_delta, const GameState
       pos.y += position_delta;
       break;
   }
+
+  if (isPortal(positionInGrid(), direction)) {
+    pos = gridPositionToPosition(teleport(positionInGrid()));
+  }
 }
 
 /*
@@ -144,6 +158,10 @@ void Ghost::updateDirection(const GameState & gameState) {
   const Position target_position = target(gameState);
 
   for (auto & move : possible_moves) {
+
+    if (isPortal(current_grid_position, move.direction))
+      move.position = gridPositionToPosition(teleport(current_grid_position));
+
     const bool invalid_position = (move.position.x < 0 || move.position.y < 0);
     if (invalid_position)
       continue;
@@ -177,4 +195,23 @@ void Ghost::updateAnimation(std::chrono::milliseconds time_delta) {
   }
 }
 
+/*
+ *  Ghosts alternate between the scatter and chase states at
+ *  specific intervals
+ */
+Ghost::State Ghost::defaultStateAtDuration(std::chrono::seconds s) {
+  // This array denotes the duration of each state, alternating between scatter and chase
+  std::array changes = { /*scatter*/ 7, 20, 7, 20, 5, 20, 5 };
+  // To know the current state we first compute the cumulative time using std::partial_sum
+  // This gives us {7, 27, 34, 54, 59, 79, 84}
+  std::partial_sum(std::begin(changes), std::end(changes), std::begin(changes));
+  // Then we look for the first value in the array greater than the time spend in chase/scatter states
+  auto it = std::upper_bound(std::begin(changes), std::end(changes), s.count());
+  // We get the position of that iterator in the array
+  auto count = std::distance(std::begin(changes), it);
+  // Because the first positition is scatter, all the even positions will be scatter
+  // all the odd positions will be chase
+  return count % 2 == 0 ? State::Scatter : State::Chase;
+}
+
 } // namespace pacman

lib/Inky.cpp

@@ -1,4 +1,5 @@
 #include "Inky.hpp"
+#include "GameState.hpp"
 
 namespace pacman {
 
@@ -22,7 +23,40 @@ Position Inky::target(const GameState & gameState) const {
   if (isInPen())
     return penDoorPosition();
 
-  return scatterTarget();
+  if (state == State::Scatter)
+    return scatterTarget();
+
+  // Inky first selects a position 2 cell away from pacman in his direction.
+  GridPosition targetPosition = gameState.pacMan.positionInGrid();
+  switch (gameState.pacMan.currentDirection()) {
+    case Direction::LEFT:
+      targetPosition.x -= 2;
+      break;
+    case Direction::RIGHT:
+      targetPosition.x += 2;
+      break;
+    case Direction::UP:
+      targetPosition.y -= 2;
+      targetPosition.x -= 2;
+      break;
+    case Direction::DOWN:
+      targetPosition.y += 2;
+      break;
+    case Direction::NONE:
+      assert("Pacman should be moving!");
+      break;
+  }
+
+  // Then it calculates the distance between Blinky and this position
+  const auto & blinkyPosition = gameState.blinky.positionInGrid();
+  auto distanceBetweenBlinkyAndTarget = std::hypot(blinkyPosition.x - targetPosition.x, blinkyPosition.y - targetPosition.y);
+
+  // And selects a point on the line crossing blinky and this position that is at twice that distance
+  // away from blinky
+  targetPosition.x += ((targetPosition.x - blinkyPosition.x) / distanceBetweenBlinkyAndTarget) * 2;
+  targetPosition.y += ((targetPosition.y - blinkyPosition.y) / distanceBetweenBlinkyAndTarget) * 2;
+
+  return gridPositionToPosition(targetPosition);
 }
 
 Position Inky::initialPosition() const {

lib/Pinky.cpp

@@ -1,4 +1,5 @@
 #include "Pinky.hpp"
+#include "GameState.hpp"
 
 namespace pacman {
 
@@ -22,7 +23,30 @@ Position Pinky::target(const GameState & gameState) const {
   if (isInPen())
     return penDoorPosition();
 
-  return scatterTarget();
+  if (state == State::Scatter)
+    return scatterTarget();
+
+  // Inky first selects a position 2 cell away from pacman in his direction.
+  GridPosition targetPosition = gameState.pacMan.positionInGrid();
+  switch (gameState.pacMan.currentDirection()) {
+    case Direction::LEFT:
+      targetPosition.x -= 4;
+      break;
+    case Direction::RIGHT:
+      targetPosition.x += 4;
+      break;
+    case Direction::UP:
+      targetPosition.y -= 4;
+      targetPosition.x -= 4;
+      break;
+    case Direction::DOWN:
+      targetPosition.y += 4;
+      break;
+    case Direction::NONE:
+      assert("Pacman should be moving!");
+      break;
+  }
+  return gridPositionToPosition(targetPosition);
 }
 
 Position Pinky::initialPosition() const {

lib/include/Ghost.hpp

@@ -41,6 +41,7 @@ private:
   void updateDirection(const GameState & gameState);
 
 protected:
+  State defaultStateAtDuration(std::chrono::seconds s);
 
   virtual double speed(const GameState & gameState) const = 0;
   virtual Position target(const GameState & gameState) const = 0;
@@ -51,8 +52,8 @@ protected:
   double timeForAnimation = 0;
   int animationIndex = 0;
   State state = State::Chase;
-  int timeFrighten = 0;
-  int timeChase = 0;
+  std::chrono::milliseconds timeFrighten = {};
+  std::chrono::milliseconds timeChase = {};
   Position pos;
   GridPosition last_grid_position = { 0, 0 };
   [[nodiscard]] bool isInPen() const;

lib/include/PacMan.hpp

@@ -27,6 +27,10 @@ public:
     return direction != Direction::NONE;
   }
 
+  Direction currentDirection() const {
+    return direction;
+  }
+
 private:
   Direction direction = Direction::NONE;
   Direction desired_direction = Direction::NONE;