////////////////////////////////////////////////////////////////////////////////
// DEMOGAME.C
//------------------------------------------------------------------------------
// FAIRLY MINIMAL GAME DEMO FOR GETTING STARTED WITH GBDK
// BY REFRESH GAMES
//------------------------------------------------------------------------------
// THIS IS INTENDED TO BE A BASE POINT FOR ANYONE TO CUSTOMISE AND ADD TO SO
// THEY CAN MAKE THEIR OWN GAMEBOY GAMES, HENCE THE COMMENTS!
//------------------------------------------------------------------------------
// WEB: refreshgames.co.uk
////////////////////////////////////////////////////////////////////////////////
#include // INCLUDE RANDOM FUNCTIONS
#include ; // INCLUDE GBDK FUNCTION LIBRARY
#include ; // INCLUDE HANDY HARDWARE REFERENCES
// FUNCTION DECLARATIONS
void initGame(); // INITIALISE OUR GAME
void updatePlayer(); // UPDATE OUR PLAYER
UINT8 collisionCheck(UINT8, UINT8, UINT8, UINT8, UINT8, UINT8, UINT8, UINT8); // SIMPLE RECT TO RECT CHECK
// VARIABLE DECLARATIONS - STORED IN RAM
UINT8 i, j; // GENERIC LOOPING VARIABLE
UINT8 playerX, playerY; // PLAYER CO-ORDINATES
UINT8 eX[10], eY[10]; // ENEMY CO-ORDINATES
UINT8 lastKeys; // HOLDS KEYS FOR THE PREVIOUS FRAME
UINT8 randomBkgTiles[20]; // CONTAINS RANDOM DATA FOR OUR BKG
// SPRITE DATA - 14 SPRITES - STORED IN ROM
const unsigned char sprites[] = {0x3C,0x3C,0x42,0x42,0xA9,0xA9,0xA9,0xA9,0x81,0x81,0x91,0x91,0x42,0x42,0x3C,0x3C,0x3C,0x3C,0x42,0x42,0x81,0x81,0xED,0xED,0x81,0x81,0x91,0x91,0x42,0x42,0x3C,0x3C,0x99,0x81,0x42,0x5A,0x24,0x3C,0x99,0x7E,0x99,0x7E,0x24,0x3C,0x42,0x5A,0x99,0x81,0x38,0x04,0x7C,0x02,0x5C,0x22,0x5C,0x22,0x5C,0x22,0x5C,0x22,0x7C,0x02,0x38,0x04,0x00,0x00,0x3E,0x3E,0x63,0x63,0x63,0x63,0x63,0x63,0x63,0x63,0x3E,0x3E,0x00,0x00,0x00,0x00,0x1C,0x1C,0x3C,0x3C,0x6C,0x6C,0x0C,0x0C,0x0C,0x0C,0x7F,0x7F,0x00,0x00,0x00,0x00,0x3E,0x3E,0x63,0x63,0x03,0x03,0x1E,0x1E,0x70,0x70,0x7F,0x7F,0x00,0x00,0x00,0x00,0x7F,0x7F,0x03,0x03,0x3E,0x3E,0x07,0x07,0x43,0x43,0x3E,0x3E,0x00,0x00,0x00,0x00,0x60,0x60,0x6C,0x6C,0x6C,0x6C,0x7F,0x7F,0x0C,0x0C,0x0C,0x0C,0x00,0x00,0x00,0x00,0x7F,0x7F,0x60,0x60,0x7E,0x7E,0x03,0x03,0x63,0x63,0x3E,0x3E,0x00,0x00,0x00,0x00,0x3F,0x3F,0x60,0x60,0x7E,0x7E,0x63,0x63,0x63,0x63,0x3E,0x3E,0x00,0x00,0x00,0x00,0x7F,0x7F,0x03,0x03,0x06,0x06,0x0C,0x0C,0x18,0x18,0x30,0x30,0x00,0x00,0x00,0x00,0x3E,0x3E,0x63,0x63,0x63,0x63,0x3E,0x3E,0x63,0x63,0x3E,0x3E,0x00,0x00,0x00,0x00,0x3E,0x3E,0x63,0x63,0x63,0x63,0x3F,0x3F,0x03,0x03,0x7E,0x7E,0x00,0x00};
//BACKGROUND DATA - 4 SPRITES - STORED IN ROM
const unsigned char myBkgData[] = {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x08,0x00,0x08,0x00,0x36,0x00,0x08,0x00,0x08,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x20,0x00,0x50,0x00,0x20,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x04,0x00,0x0E,0x00,0x04,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x50,0x00,0x20,0x00,0x50,0x00,0x00,0x00};
////////////////////////////////////////////////////////////////////////////////
// MAIN FUNCTION
void main(){
initGame(); // RAN ONCE AT STARTUP
// GAME LOOP START
while(1){
updatePlayer(); // UPDATE PLAYER
HIDE_WIN; // SHOW WINDOW LAYER
SHOW_SPRITES; // HIDE SPRITES LAYER
SHOW_BKG; // SHOW BACKGROUND LAYER
lastKeys = joypad(); // UPDATE OUR KEYPRESSES
wait_vbl_done(); // WAIT FOR VBLANK TO FINISH - ENSURES 60 FRAMES PER SECOND MAXIMUM
}
// GAME LOOP END
}
////////////////////////////////////////////////////////////////////////////////
// INIT GAME
void initGame(){
DISPLAY_ON; // TURNS ON THE GAMEBOY LCD
NR52_REG = 0x8F; // TURN SOUND ON
NR51_REG = 0x11; // ENABLE SOUND CHANNELS
NR50_REG = 0x1F; // VOLUME MAX = 0x77, MIN = 0x00
initrand(DIV_REG); // SEED OUR RANDOMIZER
set_sprite_data(0, 14, sprites); // STORE OUR SPRITE DATA AT THE START OF SPRITE VRAM
set_bkg_data(0, 4, myBkgData); // STORE OUR BKG DATA AT THE START OF BKG VRAM - NOTE, THE WINDOW LAYER SHARED THE BKG VRAM BY DEFAULT
playerX = 64; // PLAYERS INITAL X POSITION
playerY = 64; // PLAYERS INITAL Y POSITION
set_sprite_tile(0,0); //PLAYERS SPRITE TILE - 0
for (i=0; i !=10; i++){ // OUR ENEMY POSITION LOOP - NOTE, USE !=, NOT < TO SCRAPE BACK SOME CPU TIME eX[i] = 16+(rand() >> 1); // RANDOM X POSITION 16 - 144
eY[i] = 16+(rand() >> 1); // RANDOM Y POSITION 16 - 144
set_sprite_tile(i+1, 2); // ENEMIES SRITE TILE - SET TO SPRITE 2
move_sprite(i+1,eX[i], eY[i]); // POSITION ENEMIES
}
// GENERATE RANDOM BKG TILE DATA - SO STARRY!
for (j=0; j != 18; j++){
for (i=0; i != 20; i++){
randomBkgTiles[i] = rand() % 4;
}
set_bkg_tiles(0,j,20,1,randomBkgTiles); // SET A LINE OF BKG DATA (X, Y, W, H, DATA)
}
}
////////////////////////////////////////////////////////////////////////////////
// UPDATE PLAYER
void updatePlayer(){
// MOTION VIA DPAD - LIMITED TO A CERTAIN AREA ON SCREEN
// UP
if (joypad() & J_UP){
playerY--;
if (playerY == 15){
playerY = 16;
}
}
// DOWN
if (joypad() & J_DOWN){
playerY++;
if (playerY == 153){
playerY = 152;
}
}
// LEFT
if (joypad() & J_LEFT){
playerX--;
if (playerX == 7){
playerX = 8;
}
}
// RIGHT
if (joypad() & J_RIGHT){
playerX++;
if (playerX == 161){
playerX = 160;
}
}
// END MOTION VIA DPAD
// TAP A - PLAYS A RANDOM BEEP THROUGH SOUND CHANNEL 1 - SQUARE WAVE CHANNEL
if (joypad() & J_A){
NR11_REG = 0x7f; // SQUARE WAVE DUTY
NR12_REG = 0x7f; // VOLUME 0 = quietest, 255 = loudest
NR13_REG = DIV_REG; // LOWER BITS OF SOUND FREQ
NR14_REG = 0x80 + (DIV_REG % 8); // LARGER SOUND FREQ - MINIMUM OF 128 - TOP 3 BYTES - ANY LESS = SOUND CHANNEL SWITCHES OFF
} else {
NR11_REG = 0x00; // NO A BUTTON - NO SOUND
NR12_REG = 0x00;
NR13_REG = 0x00;
NR14_REG = 0x00;
}
//MOVE OUR SPRITE
move_sprite(0,playerX,playerY); // POSITION OUR SPRITE ON THE SCREEN
j=0; // RE-USE J AS A FLAG TO SEE IF WE HAVE COLLIDED WITH AN ENEMY
for (i=0; i != 10; i++){ // LOOP THROUGH OUR 10 ENEMIES
if (collisionCheck(playerX, playerY, 8, 8, eX[i], eY[i], 8, 8) == 1){
j= 1; // IF WE COLLIDED, SET OUR FLAG VARIABLE, J TO 1
}
}
// ADJUST OUR PLAYER SPRITES FRAME IF THEY HIT SOMETHING
switch (j){
// NO HIT
case 0:
set_sprite_tile(0,0);
break;
// HIT ENEMY
default:
set_sprite_tile(0,1);
break;
}
}
////////////////////////////////////////////////////////////////////////////////
// COLLISION CHECKER - SIMPLE RECTANGLE COLLISION CHECKING
// RETURNS 1 IF OVERLAPPING
UINT8 collisionCheck(UINT8 x1, UINT8 y1, UINT8 w1, UINT8 h1, UINT8 x2, UINT8 y2, UINT8 w2, UINT8 h2){
if ((x1 < (x2+w2)) && ((x1+w1) > x2) && (y1 < (h2+y2)) && ((y1+h1) > y2)){
return 1;
} else {
return 0;
}
}
Just another Saturday night and I noticed the one hour game jam was on in a minute or two. So, time to roll up those coding sleeves and bosh out a game based on the theme “Stealth”
Nevertheless, I’m glad I managed to make something “slightly” more substantial than my previous one hour game jam attempt under the theme “Everything is dangerous” again, simple enough, avoid the spikes, walls, etc. Just under an hour.