File content as of revision 18:165e3d49daa8:

/* TanksEngine.cpp
Game Engine
9.4.19
*/
#include "TanksEngine.h"

TanksEngine::TanksEngine()

{
  _tankl.set_movement_limits(0, 21);            // Prevent tanks from leaving the screen
  _tankr.set_movement_limits(54, 74);           // or passing through map obstacle
  _grav = 0.035;
}

TanksEngine::~TanksEngine()
{

}

void TanksEngine::initgame(Menus &menus)         // initialise a game based on preferences
{                                                // set in the menus, reset member variable's
    // Player Preferences:                       // values from the previous game.
  _initial_health = menus.get_health();
  _mute = menus.get_mute();
  _tankl.set_health(_initial_health);
  _tankr.set_health(_initial_health);
    // Set up Game:
  _tankl.set_position(0, 0);
  _tankr.set_position(84-10, 0);
  _turn = 1; 
  _wind = 0.00005 * (-100 + rand() % 201);       // Determines "strength" of wind in horizontal
  _fire = false;                                 // x direction.
  _move = 0;
  _cooldown_l = -1;
  _cooldown_r = -1;
  _turn_counter = 1;
    
}

void TanksEngine::game_loop(Graphics &graphics, N5110 &lcd, Gamepad &pad,   // The fundemental game loop,
                            Menus &menus, Scores &scores)                   // the phase of the game is determined
{                                                                           // by _turn. Read's gamepad and writes
  while (_turn != 0) {                                                      // to lcd.
    lcd.clear();  
    _read_input(pad); 
    graphics.draw_parkinson_map(31, 17, lcd); // Draws map obstacle on the screen.
    if (_turn == 1) {
      _left_tank_turn(graphics, pad);
    } else if (_turn == 2 || _turn == 4) {
      _projectile_phase(lcd, pad);            
    } else if (_turn == 3) {                  
      _right_tank_turn(graphics, pad);        
    } else if (_turn == 5) {
      _end(graphics, lcd, pad, scores);       // When either player drops to zero health, the 
    }                                         // game stops and an end screen is shown.
    _draw(graphics, lcd);
    lcd.refresh();
    wait_ms(1000/60); 
  } 
}

// Game Flow

void TanksEngine::_left_tank_turn(Graphics &graphics, Gamepad &pad)
{
  _tankl.move_position(_move); 
  if (_angle >= 355 && _angle <= 360 || _angle >= 0 && _angle <= 90) {         // turret must be at acceptable angle
      _tank_shoots(_tankl.get_position_x(), _tankl.get_position_y(), 2, pad);
  }
  graphics.show_health(_tankl.get_health(), pad);                              // Show player's health in LEDs
}

void TanksEngine::_right_tank_turn(Graphics &graphics, Gamepad &pad)
{
  _tankr.move_position(_move);
  if (_angle >= 270 && _angle <= 360 || _angle >= 0 && _angle <= 5) {          // turret must be at acceptable angle
      _tank_shoots(_tankr.get_position_x(), _tankr.get_position_y(), 4, pad);
  }
  graphics.show_health(_tankr.get_health(), pad);                              // Show player's health in LEDs
}

void TanksEngine::_projectile_phase(N5110 &lcd, Gamepad &pad)             // Projectile phase; where player's cannot impact game
{                                                                         // and await the projectile to leave boundaries or
  _proj.update_flight();                                                  // collide with an object.
  _proj.generate_hitbox();
  if (_proj.check_boundaries() == true) {                                 // change turn if projectile falls off left
    _change_turn();                                                       // or right side of screen.
  }               
  _object_hit(_proj.get_position_x(), _proj.get_position_y(), lcd, pad);  // Check collision with other objects based on
}                                                                         // projectile's current x and y position.

void TanksEngine::_change_turn()                               // Determines who's turn is next or if game should end.
{
  if (_tankl.get_health() == 0 || _tankr.get_health() == 0) { 
    _turn = 5;
  } else if (_turn == 2) { 
    _turn = 3; 
  } else if (_turn == 4) { 
    _turn = 1; 
    _turn_counter++;                                           // Increase turn counter for scoring purposes.
  }   
  srand(time(0));                                              // Randomly change wind in either positive or negative
  _wind = 0.00005 * (-100 + rand() % 201);                     // horizontal x direction. srand seeds the rand function.
}

void TanksEngine::_end(Graphics &graphics, N5110 &lcd, Gamepad &pad,     // End screen that shows who won and their score.
                       Scores &scores) 
{
  _turn = 0;                                                             // This allows game loop to end and top-level loop to progress
  int score = scores.score_calculator(_turn_counter, _initial_health);
  pad.check_event(Gamepad::BACK_PRESSED);                                // Clears trigger so that the end screen is not skipped due to a 
                                                                         // prevous BACK button press.
  while(pad.check_event(Gamepad::BACK_PRESSED) == false) {    
    lcd.clear();
    scores.display_score(score, lcd);
    pad.check_event(Gamepad::START_PRESSED);                             // Clear trigger so start screen is not skipped.

    if (_tankl.get_health() == 0) { 
        graphics.draw_right_victory(lcd);
    } 
    else if  (_tankr.get_health() == 0) { 
        graphics.draw_left_victory(lcd);        
    } 
    lcd.refresh();
  }
}

// Game Mechanics

void TanksEngine::_tank_shoots(int x, int y, int turn, Gamepad &pad)  // Govern's the shooting mechanic for the tanks.
{
  if (_fire == true) {                                                // _fire determined by A button; pressed = true.
    int angle = _angle;                                               // changes float _angle to an int angle for use in modulo arithmetic below.
    angle = (-angle + 90) % 360;                                      // gamepad's convention is N = 0 clockwise changed into E = 0 anticlockwise.
    x = x + 5;
    y = y + 5;
    _proj.set_launch_parameters(x, y, angle, _vel, _grav, _wind);     // set launch parameters for projectile based on tank/game parameters.
    _tankl.generate_hitbox();                                         // generate hitboxes ready to determine collision during projectile phase.
    _tankr.generate_hitbox();      
    _turn = turn;                                                     // change to projectile phase.
    _sounds(3, pad);
  }
}

void TanksEngine::_object_hit(int x, int y, N5110 &lcd, Gamepad &pad)        // Decides when to check for collsions and
{                                                                            // their impact.
  if (x >= 0 && x <= 30 && _collision_pl(_tankl, _proj) == true) {               
    _tankl.lose_health();
    _change_turn();
    _sounds(1, pad);
  } else if (x >= 55 && x <= 83 && _collision_pr(_tankr, _proj) == true) {
    _tankr.lose_health();
    _change_turn();
    _sounds(1, pad);
  } else if (x >= 31 && x <= 54 && _collision_pm(x, y, lcd, _proj) == true) {
    _change_turn();
    _sounds(2, pad);
  }
}

bool TanksEngine::_collision_pl(Tank _tankl, Projectile _proj) // Detects projectile hitting LEFT tank by comparing every 
{                                                              // element in the projectile's hitbox array to that of the 
  for (int i0 = 0; i0 < 4; i0++) {                             // tank's hitbox array.
    for (int i1 = 0; i1 < 40; i1++) {
      if (_proj.get_hitbox(i0) == _tankl.get_hitbox(i1)) { 
        return true; 
      }               
    }
  }
  return false;
}

bool TanksEngine::_collision_pr(Tank _tankr, Projectile _proj) // Detects projectile hitting RIGHT tank by comparing every 
{                                                              // element in the projectile's hitbox array to that of the 
  for (int i0 = 0; i0 < 4; i0++) {                             // tank's hitbox array.
    for (int i1 = 0; i1 < 40; i1++) {
      if (_proj.get_hitbox(i0) == _tankr.get_hitbox(i1)) {      
        return true;
      }               
    }
  }
  return false;
}

bool TanksEngine::_collision_pm(int x, int y, N5110 &lcd, Projectile _proj) // Detects projectiles hitting the MAP by comparing the
{                                                                           // position of the projectile's bottom two pixels
  if (lcd.getPixel(x, 48 - y) == 1) {                                       // to the positions on the screen. If they are occupied by a 
    return true;                                                            // pixel the map obstacle has been hit.
  } else if (lcd.getPixel(x + 1,48 - y) == 1) {
    return true; 
  } else { 
    return false ; 
  }
}

// Game Inputs

void TanksEngine::_read_input(Gamepad &pad)                                    // Detects gamepad activity and it's bearing
{                                                                              // on the game.
  _vel = 1.15 + pad.read_pot(); 
  _angle = pad.get_angle();
  _mag = pad.get_mag();   
  if (pad.check_event(Gamepad::L_PRESSED) == true && _cooldown_l < 0) {        // toggle movement to the left.
    _move = -1 * !_move; 
    _cooldown_l = 10;                                                          // Cooldown prevents multiple button presses being registered.
  } else if (pad.check_event(Gamepad::R_PRESSED) == true && _cooldown_r < 0) { // toggle movement to the right.
    _move = 1 * !_move; 
    _cooldown_r = 10;
  } else if (_turn == 2 || _turn == 4) { 
    _move = 0;                                                                 // movement cannot be triggered during projectile phase    
  } 
  if (pad.check_event(Gamepad::A_PRESSED) == true) {                           // Tank shoots if A button is pressed (assuming turret
    _fire = true;                                                              // is at an acceptable angle).
  } else { 
  _fire = false; 
  }   
  _decrement_cooldowns();                                                      
}

void TanksEngine::_decrement_cooldowns() // Prevents buttons being pressed multiple times in quick succession.
{
  _cooldown_l--;
  _cooldown_r--;
  if (_cooldown_l < -100) { 
    _cooldown_l = -1; 
  }
  if (_cooldown_r < -100) { 
    _cooldown_r = -1; 
  }
}

// Game Outputs

void TanksEngine::_draw(Graphics graphics, N5110 &lcd)                         // Draw graphics for all objects, turrets rotate 
{                                                                              // for the current tank's turn.
  graphics.draw_tank_l(_tankl.get_position_x(), _tankl.get_position_y(), lcd);
  if (_turn == 1) {
    graphics.draw_turret_l(_tankl.get_position_x(), _tankl.get_position_y(), 
                           _angle, lcd); 
    graphics.draw_wind_bar(_wind, lcd);
    if (_mag >= 0.5) {                                                         // only draw the reticle if the joystick is not in
      graphics.draw_reticle(_tankl.get_position_x(), _tankl.get_position_y(),  // a neutral position.
                            _angle, lcd);       
    }   
  }
  if (_turn == 2 || _turn == 4) {
    graphics.draw_projectile(_proj.get_position_x(), _proj.get_position_y(), 
                                                     lcd);
  }
  graphics.draw_tank_r(_tankr.get_position_x(), _tankr.get_position_y(), lcd);
  if (_turn == 3) {
    graphics.draw_turret_r(_tankr.get_position_x(), _tankr.get_position_y(), 
                                                    _angle, lcd);
    graphics.draw_wind_bar(_wind, lcd);
    if (_mag >= 0.5) {
      graphics.draw_reticle(_tankr.get_position_x(), _tankr.get_position_y(), 
                            _angle, lcd);       
    }  
  }
}

void TanksEngine::_sounds(int n, Gamepad &pad)  // Play sound relating to game event.
{
  if (_mute == false) {
    if (n == 1) {                               // tank is hit.
      pad.tone(300, 0.125);
      pad.tone(400, 0.125);
      pad.tone(500, 0.125);
    } else if (n == 2) {                        // building hit.
      pad.tone(500, 0.125);
      pad.tone(400, 0.125);
      pad.tone(300, 0.125);
    } else if (n == 3) {                        // tank shoots.
      pad.tone(200, 0.125);
    }
  }
}