File content as of revision 27:f05f4e738ba9:

#ifndef ENEMIES_H
#define ENEMIES_H

#include "constants.h"
#include "geometry.h"
#include "game.h"

extern int enemy_speed = 1;
extern int enemy_blast_speed = 3;
const int max_enemies = 4;
const int max_enemy_blasts = max_enemies*2;

    
/**@brief
  * This is a class to describe the states of one enemy ship
  */
class Enemy : public GameObject {
public:
/**This function spawns an enemy on the right side of the screen at the 
  * x-direction LCD limit(84) and at random position in the y-direction.
  */
    void spawn() {
        // giving the enemy the spawning positions 
        Point spawn_pos(screen_width, game_area_y + rand() % (game_area_height - enemy2_height));
        GameObject::spawn(spawn_pos);
        dead = false;
        dead_counter = 0;
        blast_countdown = 0;
    }
/** This is a death function of an nemy when the the collision between the 
  * player blast and enemy ship is true. It sets the enemy ship to not active.
  */
    void die() {
        gamepad.tone(87,0.1);
        gamepad.tone(187,0.2);
        gamepad.tone(123,0.3);
        dead = true;
        dead_counter = 3;
    }
/** This function draws each individual enemy ship on the screen.
  */    
    void updateAndDraw() {
        pos.x -= enemy_speed;
        if (!dead) {
            drawSprite(pos, enemy_sprite);
        } else {
            updateAndDrawDeathExplosion();
        }
        if (pos.x < 0) {
            game_score -= 50;
            score_count_for_difficulty -= 50; 
            active = false;
        }
    }
/** This is an explosion function that draws the enemy ships explosion sprites
  * when the player's shot hits it/
  */        
    void updateAndDrawDeathExplosion() {
        if (dead_counter > 0) {
            dead_counter--;
            if (dead_counter == 2){    
                drawSprite(pos, enemy_half_exploded_sprite);
            } else if (dead_counter == 1){
                drawSprite(pos, enemy_exploded_sprite);
            }
        } else {
            active = false;
        }
    }
    
    bool dead;
    int dead_counter;
    int blast_countdown;
};

    
/**@brief
  * This class describes the states and actions of several enemy ships, including
  * random position generation (y - position) and enemy ship shooting drawing (also describing
  * intervals between shots).
  */  
class Enemies {
public:

    Enemy enemy_blasts[max_enemy_blasts];
    Enemy enemies[max_enemies];
    CircleBounds enemy_bounds;
    CircleBounds enemy_blast_bounds;
    
    Enemies () {
        enemy_bounds.center.x = 5;
        enemy_bounds.center.y = 3;
        enemy_bounds.radius = 6;

        enemy_blast_bounds.center.x = 0;
        enemy_blast_bounds.center.y = 1;
        enemy_blast_bounds.radius = 1;
    }
/** This function spawns a new enemy when there is a free spance in the enemy aray.
  */  
    void spawnNewEnemy() {
        int found = -1;
        for (int i = 0; i < max_enemies; ++i) {
            if (!enemies[i].active) {
                found = i;
                break;
            }
        }
        
        if (found != -1) {
            enemies[found].spawn();
        }
    }
/** This function draws the enemy ships and enemy blasts whenever they are 
  * avaialbe to move. Also, it limits the fire rate of the enemy ships.
  */  
    void updateAndDrawEnemies() {
        for (int i = 0; i < max_enemies; ++i) {
            if (enemies[i].active){
                enemies[i].updateAndDraw();
                
                // Spawn blast on enemy if counter is ready
                enemies[i].blast_countdown -= 1;
                if (enemies[i].blast_countdown <= 0) {
                    bool fired = fireEnemyBlast(enemies[i]);
                    if (fired) {
                        enemies[i].blast_countdown = 20;
                    }
                }
            }
        }
    }
/** This function fires a blast whenever it is free in the blast array.
  * If the blast is free to be shot, it will become active and will get the.
  * positions of x and y in front of the enemy ship  
  */
    bool fireEnemyBlast(const Enemy& enemy) {
        int found = -1;
        for (int i = 0; i < max_enemy_blasts; ++i) {
            if (!enemy_blasts[i].active) {
                found = i;
                break;
            }
        }
        if (found != -1) {
            enemy_blasts[found].active = true;
            enemy_blasts[found].pos.x = enemy.pos.x;
            enemy_blasts[found].pos.y = enemy.pos.y + enemy2_height / 2;
            gamepad.tone(500,0.1);
            return true;
        }
        return false;
    }
/** Whenever the blast is active, this function draws the blast accross the    
  * x- direction of the screen until it reaches the left screen limit and then
  * becomes inactive, therefore freeing a space in the blast array. 
  */
    void updateAndDrawEnemyBlasts() {
        for (int i = 0; i < max_enemy_blasts; ++i) {
            if (enemy_blasts[i].active) {
                enemy_blasts[i].pos.x -= enemy_blast_speed;
                if (enemy_blasts[i].pos.x <= -1){
                    enemy_blasts[i].active = false;
                }
                // Blast is a line 3 pixels wide
                lcd.setPixel(enemy_blasts[i].pos.x,   enemy_blasts[i].pos.y, 1);
                lcd.setPixel(enemy_blasts[i].pos.x-1, enemy_blasts[i].pos.y, 1);
                lcd.setPixel(enemy_blasts[i].pos.x-2, enemy_blasts[i].pos.y, 1);
            }
        }
    }  
};

#endif