A simple one-level platform game. Developed as part of ELEC2645 at University of Leeds, spring 2015.

Dependencies:   N5110 PinDetect PowerControl mbed

An ARM mbed LPC1768 microcontroller have been used to develop a handheld arcade game in the style of an old-school platformer. This project is entirely my own independent work in all stages of the development; including design, defining project specifications, breadboard prototyping, schematic and PCB layout using CAD, assembly, testing and software development. Due to this being part of the ELEC2645 Embedded Systems Project module at University of Leeds, spring 2015, limitations were given on the available hardware components. Credit is due to the authors of the dependent libraries (N5110, Pin Detect, PowerControl and mbed). I would also like to thank the author of Game Programming Patterns as well as the authors of SFML Game Development for providing me with useful sources for programming design patterns.

/media/uploads/Siriagus/game_assembled.jpg

Project aims

  • Implement simple gameplay:
    • A single, fixed (no scrolling) level.
    • Player can move left to right, jump and shoot.
    • Enemies will drop from the top of the screen.
    • The player gets points for shooting enemies.
    • The player dies when it gets hits by an enemy.
  • Implement a simple menu system.
  • Enable the user to adjust the brightness of the display.
  • Output sound to enhance the user experience.

Software

The program flow is controlled by a finite state machine. The implemented design was inspired by the State design pattern from the books Game Programming Patterns and SFML Game Development. The StateManager class is responsible for updating and rendering the current selected state. It also changes the state based on request from the current state. The framework built for the state machine used in this project makes it easy to add new screens. The different main states (indicated by the background colour) and how the user interaction is shown below: /media/uploads/Siriagus/arcadegameuserinteraction.png

Hardware

Schematic:

/media/uploads/Siriagus/schematic.png

Printed circuit board (PCB):

/media/uploads/Siriagus/pcb.png

Images

A seperate program was written to convert images (png) to text-representation of the maps. Enemies and numbers on the screen are also collected from a sprite-sheet created in the same manner.

/media/uploads/Siriagus/unileeds3.png /media/uploads/Siriagus/newmap2.png

Game.cpp

Committer:
Siriagus
Date:
2015-05-11
Revision:
17:d6a3b29cab31
Parent:
16:caf613d5b85e

File content as of revision 17:d6a3b29cab31:

#include "Game.h"

/// @file Game.cpp

Game::~Game()
{
    // Free allocated memory from bullets
    for (std::vector<Point*>::iterator it = bullets.begin(); it != bullets.end(); ++it)
        delete *it;
    
    bullets.clear();
    
    // Free allocated memory from enemies
    for (std::vector<Enemy*>::iterator it = enemies.begin(); it != enemies.end(); ++it)
        delete *it;
    
    enemies.clear();
}

void Game::init()
{   
    Global::score = 0;
    paused = false;
    livesLeft = 2; 
    
    // Set initial values for the player
    player.width = player.height = 5; // important that this is correct, see size of Image::Player in Resources.h
    player.onGround = false;
    respawnPlayer();
    
    spawnRate = 2; // Probability for spawning a new enemy in percent
    spawnEnemy();
}

// temporary move to game
const int Game::spawnPoints[3][2] = {{27,20}, {2,29}, {24,45}};

void Game::spawnEnemy()
{
    // Get random spawn point
    int r = rand() % 3;
    int x = Game::spawnPoints[r][0];
    int y = Game::spawnPoints[r][1];
    
    // Spawn random enemy
    int randPercent = (rand() % 100);
    Enemy::Type type;
        
    if (randPercent >= 40)      // 60% probability
        type = Enemy::JUMPER;
    else if (randPercent >= 15) // 25% probablitiy
        type = Enemy::SIMPLE;
    else                        // 15 % probability
        type = Enemy::RUNNER;
        
    // Create enemy
    Enemy *enemy = new Enemy(x, y, true, type);
    enemies.push_back(enemy);
}

// Functions
void Game::update(float dt)
{    
    // Pause button input
    if (input->read(Input::ButtonC))
    {
        if (releasedBtnC)
        {
            paused = !paused;
            releasedBtnC = false;
        }
    }
    else
        releasedBtnC = true;
        
    // Skip the rest if paused
    if (paused) return;   
    
    if ((rand() % 100) < spawnRate )
        spawnEnemy();
        
    // Handle input, should be its own function
    switch(input->joystick->getDirection())
    {
        case LEFT:
        case UP_LEFT:
        case DOWN_LEFT:
            player.vx = -2;
            player.facingLeft = true;
        break;
        
        case RIGHT:
        case UP_RIGHT:
        case DOWN_RIGHT:
            player.vx = 2;
            player.facingLeft = false;
        break;
        
        case CENTER:
            player.vx = 0;
        break;
    }
    
    
    // MOVE: Random enemies
    
    // Gravity
    player.vy += 1;
    
    // Check if player is trying to jump. Player can only jump if it's on the ground
    if (input->read(Input::ButtonA) && player.onGround)
    {
        player.vy = -4;
        player.onGround = false;
        sound->playNote(SFX::PLAYER_JUMP);
    }
    
    // Terminal velocity 3 px/update
    if (player.vy > TERMINAL_VELOCITY) player.vy = TERMINAL_VELOCITY;
    
    if (!player.dead)
        moveWithCollisionTest(&player, map);
    else // move without testing collision agains the map
    {
        player.x += player.vx;
        player.y += player.vy;
    }
    
    
    moveEnemies();
    
    // Check if bullet should be fired
    if (input->read(Input::ButtonB) && releasedBtnB)
    {
        // Create a new bullet and give it initial values
        Point* bullet = new Point;
        bullet->x = (int)(player.x + (player.width / 2)); //(player.facingLeft) ? (player.x-1) : (player.x + player.width);
        bullet->y = player.y + 2;
        bullet->vx = (player.facingLeft) ? -4 : 4;
        bullet->vy = 0;
        
        bullets.push_back(bullet);
        releasedBtnB = false;
        
        // Play sound
        sound->playNote(SFX::BULLET_FIRED);
    }
    else if (!input->read(Input::ButtonB))
        releasedBtnB = true;
    
    // Loop through bullets and move them + collision test
    for (std::vector<Point*>::iterator it = bullets.begin(); it != bullets.end();)
    {
        Point* bullet = *it;
        
        int x0; // left border of collision rect
        int x1; // right border of collision rect
        
        int oldX = bullet->x;
        int newX = bullet->x + bullet->vx;
        
        x0 = min(oldX, newX);
        x1 = max(oldX, newX);
            
        // Collision rect for bullet in this time step
        Rectangle bulletColRect(x0, bullet->y, (x1-x0)+1, 1);
        
        bool col = false;
        // Delete if outside screen
        if (newX < 0 || newX > WIDTH || bulletHitMap(bulletColRect, map)) // if outside screen
        {
            col = true;
        }
        else
        {
            // loop through all enemies
            for (std::vector<Enemy*>::iterator ite = enemies.begin(); ite != enemies.end(); ++ite)
            {
                Enemy *enemy = *ite;
                
                // If bullet hits enemy
                //if (!enemy->dead && bullet->x >= enemy->x && bullet->x <= enemy->getRight() && bullet->y >= enemy->y && bullet->y <= enemy->getBottom()) 
                
                Rectangle enemyColRect(enemy->x, enemy->y, enemy->width, enemy->height); // collision rectangle for enemy
                
                if (!enemy->dead && hitTestRect(bulletColRect, enemyColRect))
                {
                    col = true;
                    
                    enemy->dead = true;
                    enemy->vx = bullet->vx / 2; // sends the dead enemy in the same direction as the incoming bullet
                    enemy->vy = -3;             // sends the dead enemy upwards in the air, because of impact
                    
                    Global::score += 5 * enemy->difficulty; // increase the score
                    
                    sound->playNote(SFX::ENEMY_DEAD);
                }
            }
        }
        
        if (!col)
        {
            ++it;   // go to next element
            bullet->x += bullet->vx; // update position
        }
        else
        {
            delete bullet;
            it = bullets.erase(it); // go to next element
        }
    }
    
    // Check if player hits enemy
    Rectangle playerRect(player.x, player.y, player.width, player.height);
    for (std::vector<Enemy*>::iterator it = enemies.begin(); it != enemies.end(); ++it)
    {
        Enemy *enemy = *it;
        
        if (enemy->dead) continue; // only test against living enemies
        
        Rectangle enemyRect(enemy->x, enemy->y, enemy->width, enemy->height);
        
        if (hitTestRect(playerRect, enemyRect))
        {
            player.dead = true;
            player.vx = 0;
            player.vy = -4;
            player.onGround = false;
            --livesLeft;
            
            sound->playNote(SFX::PLAYER_DEAD);
            break;
        }
    }
    
    if (player.dead)
    {
        // remove all enemies (let them fall off)
        for (std::vector<Enemy*>::iterator it = enemies.begin(); it != enemies.end(); ++it)
        {
            Enemy *enemy = *it;
            enemy->dead = true;
        }
        
        if (player.y >= HEIGHT && !enemies.size()) // when all enemies are removed
        {
            if (livesLeft)
            {
                respawnPlayer(); // Respawn player if it still have lives left
                spawnEnemy();   // Spawn an enemy right away
            }
            else
            {
                if (Global::score > Global::highscores[2].score) // If new high score
                    requestStateChange(SUBMIT_HIGHSCORE);
                else
                    requestStateChange(GAME_OVER);
            }
        }
    }
}

void Game::render()
{
    
    if (!player.dead)
    {
        // Draw map
        drawImage(map);
    }
    else
    {
        // Print lives left
        std::stringstream ss;
        ss << "Lives left: " << livesLeft;
        lcd->printString(ss.str().c_str(), 4, 2);
    }
    
    // Draw player
    drawImage(Image::Player, player.x, player.y, false, !player.facingLeft, player.dead);
    
    
    // Draw enemies
    for (std::vector<Enemy*>::iterator it = enemies.begin(); it != enemies.end(); ++it)
    {
        Enemy *enemy = *it;
        
        switch (enemy->type)
        {
            case Enemy::SIMPLE:
                drawImage(Image::EnemySimple, enemy->x, enemy->y, false, !enemy->facingLeft, enemy->dead);    
            break;
            
            case Enemy::JUMPER:
                drawImage(Image::EnemyJumper, enemy->x, enemy->y, false, !enemy->facingLeft, enemy->dead);
            break;
            
            case Enemy::RUNNER:
                drawImage(Image::EnemyRunner, enemy->x, enemy->y, false, !enemy->facingLeft, enemy->dead);
            break;
            
            default:
                ; // should not happen, don't render
        }
        
        
    }    

    // Render bullets
    for (std::vector<Point*>::iterator it = bullets.begin(); it != bullets.end(); ++it)
    {
        int x, y;
        x = (*it)->x;
        y = (*it)->y;
        
        if (x >= 0 && x < WIDTH && y >= 0 && y < HEIGHT) // Boundary check
            lcd->setPixel(x,y);
    }
    
    // Draw pause
    if (paused)
    {
        lcd->drawRect(24, 13, 40, 13, 0); // outline
        lcd->drawRect(25, 14, 38, 11, 2); // white fill
        lcd->printString("Paused", 27, 2); // text
    }
    
    // GUI
    renderScore();
}

// Collision test between entites and map
void Game::moveWithCollisionTest(Entity* entity, const int map[HEIGHT][WIDTH])
{   
    int x = entity->x;
    int y = entity->y;
    int steps = abs(entity->vx); // how many units (pixels) the entity should move in said direction
    bool collision; // true if colliding
    
    // Check x-axis
    if (entity->vx > 0) // moving right
    {
        int entityRight = x + entity->width - 1; // Need to check right border of entity, since it is moving right
        
        while(steps--) // While it still have more movement left
        {
            collision = false;
            
            // Wrapping
            if (entityRight+1 >= WIDTH)
                entityRight = -1;// wants entityRight = -1, so next check is entityRight 0*/
            
            for (int i = 0; i < entity->height; ++i) // Loop through all vertical points on the right hand side of the entity (y+i)
            {
                if (map[y+i][entityRight+1]) // If moving to the right leads to collision for given y+i
                {
                    // Slope + allows player to climb to top of platform by going right if it hits close to top of wall.
                    if (!map[y+i-1][entityRight+1] && entity->onGround)
                    {
                        entity->vy = -1;
                    }
                    else
                    {
                        collision = true; // Then collision is true
                        break;            // Skip the for loop, no need for further testing
                    }
                        
                }
            }
            
            if (collision) // If collision
                break;     // skip the while loop, entity can not move further, even though its velocity is higher
            else
                ++entityRight;  // Move entity one px to the right
        }
        
        // If wrap didn't work, make sure entity is on the correct side of the map
        if (entityRight < 0)
            entityRight = WIDTH-1;
            
        entity->x = entityRight - (entity->width - 1); // Update entity's position. Need to set upper-left pixel.
    }
    else // moving left
    {
        while(steps--) // While still movement left
        {
            collision = false;
            
            // Wrap around map
            if (x-1 < 0)
                x = WIDTH; // causes x-1 in the next check to be WIDTH - 1
            
            // Check for all y-positions
            for (int i = 0; i < entity->height; ++i)
            {
                
                if (map[y+i][x-1])                  // If solid block
                {
                    if (!map[y+i-1][x-1] && entity->onGround) // If slope or close to top of wall (=> can climb by going left).
                    {
                        entity->vy = -1;   
                    }
                    else
                    {
                        collision = true;
                        break;                          // Collision detected, no further testing required
                    }
                }
            }
            
            if (collision)
                break;
            else
                --x;    // Move to the left if no collision is detected
        }
        
        x %= WIDTH; // In case wrapping caused entity to crash with wall on other side, x should be 0 instead of WIDTH (invalid).
        
        entity->x = x; // update position
    }
    
    // Check collision with map in y-direction - works the same way as the x-axis, except for other axis
    x = entity->x;
    y = entity->y;
    steps = abs(entity->vy);
    
    if (entity->vy > 0) // downwards
    {
        int entityBottom = y + entity->height - 1; // Need to check if bottom part collides
        while(steps--)  // Still movement left
        {
            collision = false;

            for (int i = 0; i < entity->width; ++i)  // Loop through all x-position on lower part of entity
            {   
                if (map[(entityBottom+1) % HEIGHT][x+i])       // If moving the entity one step down for a given (x+i)-position gives a collision
                {
                    collision = true;
                    break;                          // No further testing required
                }
            }
            
            if (collision)                          // If collision
            {
                entity->vy = 0;                      // Set vertical velocity to 0 (playe
                entity->onGround = true;             // entity has hit ground
                break;                               // Skip the while loop as the entity can not move further downwards
            }
            else                // Can safely move entity without collision
            {
                ++entityBottom; // Move entity one step down
                entity->onGround = false;
            }
        }
        
        // Wrapping
        y = (entityBottom - (entity->height - 1));
        if (y >= HEIGHT)            // if completely outside map
            y = -entity->height;    // wrap to top of map
            
        entity->y = y; // (entityBottom - (entity->height - 1));      // Update position when done moving, remember that entity.y refers to upper part of the entity
    }
    else // moving up, check collision from top
    {
        while(steps--)  // Still movement left
        {
            collision = false;
                            
            for (int i = 0; i < entity->width; ++i) // Check for all x-positions
            {
                int y1 = ((y-1) + HEIGHT) % HEIGHT; // In case negative, because of wrapping
                
                if (map[y1][x+i])                  // If moving upwards gives collision for a given x+i
                {
                    collision = true;               // Then we have a collision
                    break;                          // No further testing needed, skip for loop
                }
            }
            
            if (collision)  // If collision was detected
            {
                entity->vy = 0;  // Set vertical velocity to zero
                break;          // Skip while loop as entity can not move further up
            }
            else            // If safe to move for all x-values
                --y;        // Move entity one step up
        }
        
        // Wrapping
        if (y + (entity->height - 1) < 0)          // completely outside map (bottom of entity over top of map)
            y = HEIGHT-1 - entity->height - 1;     // Sets the altitude.
            
        entity->y = y;       // Update vertical position of entity
    }    
}

bool Game::hitTestRect(Rectangle r1, Rectangle r2)
{
    return ((r1.x + r1.width > r2.x)       // r1's right edge to the right of r2's left edge
        &&  (r1.x < r2.x + r2.width)       // r1's left edge to the left of r2's right edge
        &&  (r1.y + r2.height > r2.y)      // r1's bottom lower than r2's top
        &&  (r1.y < r2.y + r2.height));    // r1's top higher than r2's bottom
        
    // Note: Right border: r1.x + r1.width - 1, but we don't need to subtract 1 as we use > instead of >=
}

bool Game::bulletHitMap(Rectangle &bulletColRect, const int map[HEIGHT][WIDTH])
{
    for (int j = 0; j < bulletColRect.width; ++j)
    {
        if (map[bulletColRect.y][bulletColRect.x + j])
            return true;
    }
    
    return false;
}

void Game::moveEnemies()
{
    for (std::vector<Enemy*>::iterator it = enemies.begin(); it != enemies.end(); )
    {   
        Enemy *enemy = *it;
        
        // Gravity
        enemy->vy += 1;
        
        if (!enemy->dead)
        {
            // Random movement for enemies
            if (enemy->onGround && (rand() % 100) < enemy->jumpRate)
            {
                // jump
                enemy->vy = -3;
                enemy->onGround = false;
            }
            else if ((rand() % 100) > 98) // 2% chance
            {
                // switch direction
                enemy->vx *= -1;
                enemy->facingLeft = (enemy->vx < 0);
            }
            
            moveWithCollisionTest(enemy, map);
            
            // Enemy AI
            if (enemy->y >= 0)
            {
                int nextRight = enemy->getRight() + 1;   // Next position of right edge if enemy moves to the right
                nextRight %= WIDTH; // wrapping
                for (int i = 0; i < enemy->height; ++i)  // Check for all heighs
                {
                    // Check if crashing if moving right or left. Bounds should already be limited by moveWithCollisionTest!
                    if (map[enemy->y + i][nextRight] || map[enemy->y + i][enemy->x - 1])
                    {
                        enemy->vx *= -1; // move in opposite direction
                        enemy->facingLeft = !enemy->facingLeft; // toggle direction
                        break;          // no further testing required
                    }
                }
            }
            
            ++it;   // go to next enemy
        }
        else    // if enemy is dead
        {
            enemy->y += enemy->vy;
            enemy->x += enemy->vx;
            
            if (enemy->y >= HEIGHT) // if outside map (and dead)
            {
                delete enemy;
                it = enemies.erase(it); // remove and go to next enemy
            }
            else
                ++it;   // go to next enemy
        }
    }   
}

void Game::renderScore()
{
    int s = (Global::score < 100000) ? Global::score : 99999; // Max possible score is 99999.
    
    // Read digits
    int digits[5]; // max five
    // Count the number of digits in the score
    int numDigits = 0;
    do
    {
        digits[numDigits] = s % 10;
        s /= 10;
        ++numDigits;
    } while (s != 0 && numDigits < 5);
    
    
    // Draw score
    int xStart = 79;
    int xStep = 4; // width + 1
    int y = 2;
    int x;
    
    for (int i = 0; i < numDigits; ++i)
    {
        x = xStart - i * xStep;
        
        switch (digits[i])
        {
            case 1:
                drawImage(Number::One, x, y);
            break;
            
            case 2:
                drawImage(Number::Two, x, y);
            break;
            
            case 3:
                drawImage(Number::Three, x, y);
            break;
            
            case 4:
                drawImage(Number::Four, x, y);
            break;
            
            case 5:
                drawImage(Number::Five, x, y);
            break;
            
            case 6:
                drawImage(Number::Six, x, y);
            break;
            
            case 7:
                drawImage(Number::Seven, x, y);
            break;
            
            case 8:
                drawImage(Number::Eight, x, y);
            break;
            
            case 9:
                drawImage(Number::Nine, x, y);
            break;
            
            case 0:
            default:
                drawImage(Number::Zero, x, y);
            break;
        }
                
    }
}

void Game::respawnPlayer()
{
    player.x = 74;
    player.y = 31;
    player.vx = player.vy = 0;
    player.facingLeft = true;   
    player.dead = false;
}