rpi4-osdev/part6-breakout/kernel.c

#include "fb.h"
#include "io.h"

// The screen
#define WIDTH         1920
#define HEIGHT        1080
#define MARGIN        30
#define VIRTWIDTH     (WIDTH-(2*MARGIN))
#define FONT_BPG      8

// For the bricks
#define ROWS          5
#define COLS          10
unsigned int bricks = ROWS * COLS;

// Gameplay
#define NUM_LIVES     3

// OBJECT TRACKING

struct Object
{
    unsigned int type;
    unsigned int x;
    unsigned int y;
    unsigned int width;
    unsigned int height;
    unsigned char alive;
};

enum {
    OBJ_NONE   = 0,
    OBJ_BRICK  = 1,
    OBJ_PADDLE = 2,
    OBJ_BALL   = 3
};

unsigned int numobjs = 0;
struct Object objects[(ROWS * COLS) + (2 * NUM_LIVES)];
struct Object *ball;
struct Object *paddle;

void removeObject(struct Object *object)
{
    drawRect(object->x, object->y, object->x + object->width, object->y + object->height, 0, 1);
    object->alive = 0;
}

void moveObject(struct Object *object, int xoff, int yoff)
{
    moveRect(object->x, object->y, object->width, object->height, xoff, yoff, 0x00);
    object->x = object->x + xoff;
    object->y = object->y + yoff;
}

struct Object *detectCollision(struct Object *with, int xoff, int yoff)
{
    for (int i=0; i<numobjs;i++) {
	if (&objects[i] != with && objects[i].alive == 1) {
	   if (with->x + xoff > objects[i].x + objects[i].width || objects[i].x > with->x + xoff + with->width) {
              // with is too far left or right to ocllide
	   } else if (with->y + yoff > objects[i].y + objects[i].height || objects[i].y > with->y + yoff + with->height) {
              // with is too far up or down to ocllide
	   } else {
	      // Collision!
	      return &objects[i];
	   }
        }
    }
    return 0;
}

// KEY HANDLER

unsigned char getUart()
{
    unsigned char ch = 0;

    if (uart_isReadByteReady()) ch = uart_readByte();
    return ch;
}

// OBJECT INITIALISERS

void initBricks()
{
    int brickwidth = 32;
    int brickheight = 8;
    int brickspacer = 20;
    int brickcols[5] = { 0x11, 0x22, 0xEE, 0x44, 0x66 };

    int ybrick = MARGIN + brickheight;

    for (int i=0; i<ROWS; i++) {
       int xbrick = MARGIN + (VIRTWIDTH/COLS/2) - (brickwidth/2);
        
       for (int j = 0; j<COLS; j++) {
          drawRect(xbrick, ybrick, xbrick+brickwidth, ybrick+brickheight, brickcols[i], 1);

	  objects[numobjs].type = OBJ_BRICK;
	  objects[numobjs].x = xbrick;
	  objects[numobjs].y = ybrick;
	  objects[numobjs].width = brickwidth;
	  objects[numobjs].height = brickheight;
	  objects[numobjs].alive = 1;
	  numobjs++;

          xbrick += (VIRTWIDTH/COLS);
        }
        ybrick = ybrick + brickspacer;
     }
}

void initBall()
{
    int ballradius = 15;

    drawCircle(WIDTH/2, HEIGHT/2, ballradius, 0x55, 1);

    objects[numobjs].type = OBJ_BALL;
    objects[numobjs].x = (WIDTH/2) - ballradius;
    objects[numobjs].y = (HEIGHT/2) - ballradius;
    objects[numobjs].width = ballradius * 2;
    objects[numobjs].height = ballradius * 2;
    objects[numobjs].alive = 1;
    ball = &objects[numobjs];
    numobjs++;
}

void initPaddle()
{
    int paddlewidth = 80;
    int paddleheight = 20;

    drawRect((WIDTH-paddlewidth)/2, (HEIGHT-MARGIN-paddleheight), (WIDTH-paddlewidth)/2 + paddlewidth, (HEIGHT-MARGIN), 0x11, 1);

    objects[numobjs].type = OBJ_PADDLE;
    objects[numobjs].x = (WIDTH-paddlewidth)/2;
    objects[numobjs].y = (HEIGHT-MARGIN-paddleheight);
    objects[numobjs].width = paddlewidth;
    objects[numobjs].height = paddleheight;
    objects[numobjs].alive = 1;
    paddle = &objects[numobjs];
    numobjs++;
}

void drawScoreboard(int score, int lives)
{
    char tens = score / 10; score -= (10 * tens);
    char ones = score;

    char string[] = "Score: 0xx   Lives: x\0\0";

    string[8] = tens + 0x30;
    string[9] = ones + 0x30;
    string[20] = (char)lives + 0x30;

    drawString((WIDTH/2)-252, MARGIN-25, string, 0x0f, 3);
}

void main()
{
    struct Object *foundObject;
    unsigned char ch = 0;

    int lives = NUM_LIVES;
    int points = 0;
    
    int velocity_x = 1;
    int velocity_y = 3;

    uart_init();
    fb_init();

    initBricks();
    initBall();
    initPaddle();
    drawScoreboard(points, lives);

    while (!getUart()); // Wait for keypress to start game
     
    while (lives > 0 && bricks > 0) {
       // Get any waiting input and flush the buffer
       if ( ( ch = getUart() ) ) {
	  if (ch == 'l') if (paddle->x + paddle->width + (paddle->width / 2) <= WIDTH-MARGIN) moveObject(paddle, paddle->width / 2, 0);
	  if (ch == 'h') if (paddle->x >= MARGIN+(paddle->width / 2)) moveObject(paddle, -(paddle->width / 2), 0);
       }
       uart_loadOutputFifo();

       // Are we going to hit anything?
       foundObject = detectCollision(ball, velocity_x, velocity_y);

       if (foundObject) {
          if (foundObject == paddle) {
             velocity_y = -velocity_y;
	     // Are we going to hit the side of the paddle
	     if (ball->x + ball->width + velocity_x == paddle->x || ball->x + velocity_x == paddle->x + paddle->width) velocity_x = -velocity_x;
          } else if (foundObject->type == OBJ_BRICK) {
             removeObject(foundObject);
             velocity_y = -velocity_y;
             bricks--;
             points++;
             drawScoreboard(points, lives);
          }
       }

       wait_msec(4000); // Wait a little...
       moveObject(ball, velocity_x, velocity_y);

       // Check we're in the game arena still
       if (ball->x + ball->width >= WIDTH-MARGIN) {
          velocity_x = -velocity_x;
       } else if (ball->x <= MARGIN) {
          velocity_x = -velocity_x;
       } else if (ball->y + ball->height >= HEIGHT-MARGIN) {
          lives--;

	  removeObject(ball);
	  removeObject(paddle);

          initBall();
          initPaddle();
          drawScoreboard(points, lives);
       } else if (ball->y <= MARGIN) {
          velocity_y = -velocity_y;
       }
    }

    int zoom = WIDTH/192;
    int strwidth = 10 * FONT_BPG * zoom;
    int strheight = FONT_BPG * zoom;

    if (bricks == 0) drawString((WIDTH/2)-(strwidth/2), (HEIGHT/2)-(strheight/2), "Well done!", 0x02, zoom);
    else drawString((WIDTH/2)-(strwidth/2), (HEIGHT/2)-(strheight/2), "Game over!", 0x04, zoom);

    while (1);
}