I decided to evaluate a Java game and I chose the famous snake game (actually "snake pit") , since I am just a begginer at these things I need some help :sad: !

What are the typical Java characteristics in this game?? (How can I recognise that this is a Java game - my friend says I can find it all in the source code, but I just dont get it!!!)

Any comment will be usefull!
Please help!!!!

This is the game source code:

/************************************************************************************************
SnakePit.java
Usage:
<applet code="SnakePit.class" width=625 height=430></applet>
Keyboard Controls:
S - Start Game
P - Pause Game
M - Mute Sound
Cursor Keys - Change Direction
************************************************************************************************/
import java.awt.*;
import java.net.*;
import java.util.*;
import java.applet.Applet;
import java.applet.AudioClip;
/************************************************************************************************
Main applet code.
************************************************************************************************/
public class SnakePit extends Applet implements Runnable {
// Thread control variables.
Thread loopThread;
Thread loadThread;
// Constants
static final int MAX_DELAY = 75; // Milliseconds between screen updates.
static final int MIN_DELAY = 50;
static final int DELAY_INCR = 5;
static final int GRID_WIDTH = 39; // Size of playing field.
static final int GRID_HEIGHT = 25;
static final int GRID_SIZE = 16; // Grid size in pixels.
static final int NUM_LEVELS = 5; // Number of levels.
static final int NUM_MICE = 6; // Number of active mice.
static final int NUM_LIVES = 3; // Starting number of lives.
static final int INIT = 1; // Game states.
static final int PLAY = 2;
static final int LEVEL = 3;
static final int END = 4;
static final int OVER = 5;
static final int END_COUNT = 30; // Counter values.
static final int LEVEL_COUNT = 40;
static final int TYPE_MASK = 0x00FF0000; // Grid cell types.
static final int EMPTY = 0x00000000;
static final int BLOCK = 0x00010000;
static final int SNAKE = 0x00020000;
static final int MOUSE = 0x00030000;
static final int KEY = 0x00040000;
static final int DIR_MASK = 0x0000FF00; // Grid cell directions.
static final int NONE = 0x00000000;
static final int LEFT = 0x00000100;
static final int RIGHT = 0x00000200;
static final int UP = 0x00000300;
static final int DOWN = 0x00000400;
static final int SHAPE_MASK = 0x000000FF; // Grid cell shapes.
static final int SQUARE = 0x00000000;
static final int SNAKEHEAD = 0x00000001;
static final int SNAKEBODY = 0x00000002;
static final int SNAKEELB1 = 0x00000003;
static final int SNAKEELB2 = 0x00000004;
static final int SNAKETAIL = 0x00000005;
static final int MOUSEBODY = 0x00000006;
static final int KEYSHAPE = 0x00000007;
static final int MOUSE_POINTS = 10; // Scoring values.
static final int LEVEL_POINTS = 200;
static final int EXTRA_LIFE = 500;
// Sizing data.
int width;
int height;
// Game data.
int score; // Scoring data.
int highScore;
int lives;
int extraLife;
int level; // Level data.
int levelTotal;
int miceNeeded;
int miceEaten;
int delay;
int[][] grid; // Playing field.
Point[] snake; // Snake data.
int headPtr;
int tailPtr;
int direction;
int lastDirection;
boolean lockKeys;
Point[] mouse; // Mouse data.
Point key; // Key data.
boolean keyActive;
int gameState; // Game state data.
int levelCounter;
int endCounter;
boolean paused;
// Screen colors.
Color bgColor = Color.black;
Color fgColor = Color.white;
Color blockColor = new Color(0, 0, 153);
Color fieldColor = new Color(204, 153, 102);
Color snakeColor = new Color(0, 153, 0);
Color mouseColor = Color.gray;
Color keyColor = new Color(204, 102, 102);
// Basic shapes.
Polygon snakeHead;
Polygon snakeBody;
Polygon snakeTail;
Polygon snakeElb1;
Polygon snakeElb2;
Polygon mouseBody;
Polygon keyShape;
// Sound data.
boolean loaded = false;
boolean sound;
AudioClip bonkSound;
AudioClip munchSound;
AudioClip squeakSound;
AudioClip chimeSound;
AudioClip advanceSound;
// Values for the offscreen image.
Dimension offDimension;
Image offImage;
Graphics offGraphics;
// Font data.
Font font = new Font("Helvetica", Font.BOLD, 12);
FontMetrics fm;
int fontWidth;
int fontHeight;
// Applet information.
public String getAppletInfo() {
return("Snake Pit, Copyright 1998 by Mike Hall.");
}
public void init() {
Graphics g;
int i;
// Take credit.
System.out.println("Snake Pit, Copyright 1998 by Mike Hall.");
// Set font data.
g = getGraphics();
g.setFont(font);
fm = g.getFontMetrics();
fontWidth = fm.getMaxAdvance();
fontHeight = fm.getHeight();
// Define the playing grid.
grid = new int[GRID_WIDTH][GRID_HEIGHT];
// Initialize basic shapes.
snakeHead = new Polygon();
snakeHead.addPoint(4, 15);
snakeHead.addPoint(3, 14);
snakeHead.addPoint(1, 12);
snakeHead.addPoint(1, 8);
snakeHead.addPoint(3, 6);
snakeHead.addPoint(3, 4);
snakeHead.addPoint(6, 1);
snakeHead.addPoint(9, 1);
snakeHead.addPoint(12, 4);
snakeHead.addPoint(12, 6);
snakeHead.addPoint(14, 8);
snakeHead.addPoint(14, 12);
snakeHead.addPoint(12, 14);
snakeHead.addPoint(11, 15);
snakeBody = new Polygon();
snakeBody.addPoint(11, 0);
snakeBody.addPoint(11, 15);
snakeBody.addPoint(4, 15);
snakeBody.addPoint(4, 0);
snakeElb1 = new Polygon();
snakeElb1.addPoint(11, 0);
snakeElb1.addPoint(11, 4);
snakeElb1.addPoint(15, 4);
snakeElb1.addPoint(15, 11);
snakeElb1.addPoint(7, 11);
snakeElb1.addPoint(4, 8);
snakeElb1.addPoint(4, 0);
snakeElb2 = mirror(snakeElb1);
snakeTail = new Polygon();
snakeTail.addPoint(11, 0);
snakeTail.addPoint(8, 15);
snakeTail.addPoint(7, 15);
snakeTail.addPoint(4, 0);
mouseBody = new Polygon();
mouseBody.addPoint(8, 1);
mouseBody.addPoint(12, 5);
mouseBody.addPoint(12, 6);
mouseBody.addPoint(10, 7);
mouseBody.addPoint(12, 9);
mouseBody.addPoint(12, 12);
mouseBody.addPoint(10, 14);
mouseBody.addPoint(5, 14);
mouseBody.addPoint(3, 12);
mouseBody.addPoint(3, 9);
mouseBody.addPoint(5, 7);
mouseBody.addPoint(3, 6);
mouseBody.addPoint(3, 5);
mouseBody.addPoint(7, 1);
keyShape = new Polygon();
keyShape.addPoint(1, 6);
keyShape.addPoint(7, 6);
keyShape.addPoint(9, 4);
keyShape.addPoint(13, 4);
keyShape.addPoint(15, 6);
keyShape.addPoint(15, 10);
keyShape.addPoint(13, 12);
keyShape.addPoint(9, 12);
keyShape.addPoint(7, 10);
keyShape.addPoint(3, 10);
keyShape.addPoint(3, 11);
keyShape.addPoint(0, 11);
keyShape.addPoint(0, 7);
// Initialize data.
highScore = 0;
sound = true;
snake = new Point[GRID_WIDTH * GRID_HEIGHT];
for (i = 0; i < snake.length; i++)
snake[i] = new Point(-1, -1);
mouse = new Point[NUM_MICE];
for (i = 0; i < NUM_MICE; i++)
mouse[i] = new Point(-1, -1);
key = new Point(-1, -1);
lockKeys = false;
initGame();
endGame();
for (i = 0; i < NUM_MICE; i++)
killMouse(i);
gameState = INIT;
}
public void initGame() {
// Initialize game data.
score = 0;
lives = NUM_LIVES;
level = 0;
levelTotal = 0;
extraLife = EXTRA_LIFE;
delay = MAX_DELAY;
paused = false;
initLevel();
}
public void endGame() {
gameState = OVER;
}
public void initLevel() {
int i;
// Advance level. Once we have gone thru each, start at the beginning and
// increase speed.
level++;
if (level > NUM_LEVELS) {
level = 1;
if (delay > MIN_DELAY)
delay -= DELAY_INCR;
}
// Level total for display.
levelTotal++;
// Initialize game data.
initBlocks();
initSnake();
for (i = 0; i < NUM_MICE; i++)
initMouse(i);
miceEaten = 0;
miceNeeded = 3 * (NUM_MICE + NUM_LEVELS - level);
keyActive = false;
gameState = PLAY;
}
public void endLevel() {
// Start counter to pause before changing level.
gameState = LEVEL;
levelCounter = LEVEL_COUNT;
}
 
public void initLife() {
// Create a new snake.
killSnake();
initSnake();
gameState = PLAY;
}
public void endLife() {
// Start counter to pause before starting a new snake.
gameState = END;
endCounter = END_COUNT;
}
public void start() {
if (loopThread == null) {
loopThread = new Thread(this);
loopThread.start();
}
if (!loaded && loadThread == null) {
loadThread = new Thread(this);
loadThread.start();
}
}
public void stop() {
if (loopThread != null) {
loopThread.stop();
loopThread = null;
}
if (loadThread != null) {
loadThread.stop();
loadThread = null;
}
}
public void run() {
int i;
long startTime;
// Lower this thread's priority and get the current time.
Thread.currentThread().setPriority(Thread.MIN_PRIORITY);
startTime = System.currentTimeMillis();
// Run thread for loading sounds.
if (!loaded && Thread.currentThread() == loadThread) {
loadSounds();
loaded = true;
loadThread.stop();
}
// This is the main loop.
while (Thread.currentThread() == loopThread) {
if (!paused) {
// Move snake and mice.
if (gameState == PLAY) {
moveSnake();
for (i = 0; i < NUM_MICE; i++)
moveMouse(i);
}
// Check the score and advance high score if necessary.
if (score > highScore)
highScore = score;
// Add an extra life if score is high enough.
if (score >= extraLife) {
lives++;
extraLife += EXTRA_LIFE;
}
// See if the snake was killed. If any lives are left, continue with
// a new one.
if (gameState == END && --endCounter < 0)
if (--lives == 0)
endGame();
else
initLife();
// If enough mice have been eaten, show the key.
if (gameState == PLAY && miceEaten == miceNeeded && !keyActive) {
if (loaded && sound)
chimeSound.play();
initKey();
}
// If level was completed, go to the next one when the counter finishes.
if (gameState == LEVEL && --levelCounter < 0)
initLevel();
}
// Update the screen and set the timer for the next loop.
repaint();
try {
if (gameState == PLAY)
startTime += delay;
else
startTime += MIN_DELAY;
Thread.sleep(Math.max(0, startTime - System.currentTimeMillis()));
}
catch (InterruptedException e) {
break;
}
}
}
public void loadSounds() {
// Load all sound clips by playing and immediately stopping them.
try {
bonkSound = getAudioClip(new URL(getDocumentBase(), "bonk.au"));
munchSound = getAudioClip(new URL(getDocumentBase(), "munch.au"));
squeakSound = getAudioClip(new URL(getDocumentBase(), "squeak.au"));
chimeSound = getAudioClip(new URL(getDocumentBase(), "chime.au"));
advanceSound = getAudioClip(new URL(getDocumentBase(), "advance.au"));
}
catch (MalformedURLException e) {}
bonkSound.play(); bonkSound.stop();
munchSound.play(); munchSound.stop();
squeakSound.play(); squeakSound.stop();
chimeSound.play(); chimeSound.stop();
advanceSound.play(); advanceSound.stop();
}
public boolean keyDown(Event e, int key) {
// Check if any cursor keys have been pressed and set direction but don't
// allow a reversal of direction.
if (!paused && !lockKeys) {
if (key == Event.LEFT && lastDirection != RIGHT)
direction = LEFT;
else if (key == Event.RIGHT && lastDirection != LEFT && lastDirection != NONE)
direction = RIGHT;
else if (key == Event.UP && lastDirection != DOWN)
direction = UP;
else if (key == Event.DOWN && lastDirection != UP)
direction = DOWN;
}
// 'M' key: toggle sound.
if (key == 109) {
if (sound) {
bonkSound.stop();
munchSound.stop();
squeakSound.stop();
chimeSound.stop();
advanceSound.stop();
}
sound = !sound;
}
// 'P' key: toggle pause mode.
if (key == 112)
paused = !paused;
// 'S' key: start the game, if not already in progress.
if (loaded && key == 115 && (gameState == INIT || gameState == OVER))
initGame();
return true;
}
public void initBlocks() {
int i, j;
// Clear the grid.
for (i = 0; i < GRID_WIDTH; i++)
for (j = 0; j < GRID_HEIGHT; j++)
grid[i][j] = EMPTY | NONE | SQUARE;
// Add outer walls.
for (i = 0; i < GRID_WIDTH; i++) {
grid[i][0] = BLOCK | NONE | SQUARE;
grid[i][GRID_HEIGHT - 1] = BLOCK | NONE | SQUARE;
}
for (j = 1; j < GRID_HEIGHT - 1; j++) {
grid[0][j] = BLOCK | NONE | SQUARE;
grid[GRID_WIDTH - 1][j] = BLOCK | NONE | SQUARE;
}
// Add inner walls depending on current level.
if (level == 2 || level == 4) {
i = GRID_WIDTH / 4;
for (j = GRID_HEIGHT / 4; j <= GRID_HEIGHT / 2 - 3; j++) {
grid[i][j] = BLOCK | NONE | SQUARE;
grid[GRID_WIDTH - 1 - i][j] = BLOCK | NONE | SQUARE;
grid[i][GRID_HEIGHT - 1 - j] = BLOCK | NONE | SQUARE;
grid[GRID_WIDTH - 1 - i][GRID_HEIGHT - 1 - j] = BLOCK | NONE | SQUARE;
}
j = GRID_HEIGHT / 4;
for (i = GRID_WIDTH / 4; i <= GRID_WIDTH / 2 - 3; i++) {
grid[i][j] = BLOCK | NONE | SQUARE;
grid[GRID_WIDTH - 1 - i][j] = BLOCK | NONE | SQUARE;
grid[i][GRID_HEIGHT - 1 - j] = BLOCK | NONE | SQUARE;
grid[GRID_WIDTH - 1 - i][GRID_HEIGHT - 1 - j] = BLOCK | NONE | SQUARE;
}
}
if (level == 3) {
i = GRID_WIDTH / 2;
for (j = 0; j <= 3; j++) {
grid[i][j] = BLOCK | NONE | SQUARE;
grid[i][GRID_HEIGHT - 1 - j] = BLOCK | NONE | SQUARE;
}
}
if (level == 3 || level == 5) {
j = GRID_HEIGHT / 4;
for (i = 5; i <= GRID_WIDTH / 4; i++) {
grid[i][j] = BLOCK | NONE | SQUARE;
grid[GRID_WIDTH - 1 - i][j] = BLOCK | NONE | SQUARE;
grid[i][GRID_HEIGHT - 1 - j] = BLOCK | NONE | SQUARE;
grid[GRID_WIDTH - 1 - i][GRID_HEIGHT - 1 - j] = BLOCK | NONE | SQUARE;
}
i = GRID_WIDTH / 4;
for (j = GRID_HEIGHT / 4; j <= GRID_HEIGHT / 2; j++) {
grid[i][j] = BLOCK | NONE | SQUARE;
grid[GRID_WIDTH - 1 - i][j] = BLOCK | NONE | SQUARE;
grid[i][GRID_HEIGHT - 1 - j] = BLOCK | NONE | SQUARE;
grid[GRID_WIDTH - 1 - i][GRID_HEIGHT - 1 - j] = BLOCK | NONE | SQUARE;
}
j = GRID_HEIGHT / 2;
for (i = 0; i <= GRID_WIDTH / 4 - 5; i++) {
grid[i][j] = BLOCK | NONE | SQUARE;
grid[GRID_WIDTH - 1 - i][j] = BLOCK | NONE | SQUARE;
}
}
if (level == 4) {
i = 4;
for (j = GRID_HEIGHT / 2 - 2; j <= GRID_HEIGHT / 2; j++) {
grid[i][j] = BLOCK | NONE | SQUARE;
grid[GRID_WIDTH - 1 - i][j] = BLOCK | NONE | SQUARE;
grid[i][GRID_HEIGHT - 1 - j] = BLOCK | NONE | SQUARE;
grid[GRID_WIDTH - 1 - i][GRID_HEIGHT - 1 - j] = BLOCK | NONE | SQUARE;
}
i = GRID_WIDTH / 2;
for (j = 0; j <= 2; j++) {
grid[i][j] = BLOCK | NONE | SQUARE;
grid[i][GRID_HEIGHT - 1 - j] = BLOCK | NONE | SQUARE;
}
}
if (level == 5) {
i = 3 * GRID_WIDTH / 8;
for (j = 4; j <= GRID_HEIGHT / 3 - 1; j++) {
grid[i][j] = BLOCK | NONE | SQUARE;
grid[GRID_WIDTH - 1 - i][j] = BLOCK | NONE | SQUARE;
grid[i][GRID_HEIGHT - 1 - j] = BLOCK | NONE | SQUARE;
grid[GRID_WIDTH - 1 - i][GRID_HEIGHT - 1 - j] = BLOCK | NONE | SQUARE;
}
j = GRID_HEIGHT / 3 - 1;
for (i = 3 * GRID_WIDTH / 8; i <= GRID_WIDTH / 2; i++) {
grid[i][j] = BLOCK | NONE | SQUARE;
grid[GRID_WIDTH - 1 - i][j] = BLOCK | NONE | SQUARE;
grid[i][GRID_HEIGHT - 1 - j] = BLOCK | NONE | SQUARE;
grid[GRID_WIDTH - 1 - i][GRID_HEIGHT - 1 - j] = BLOCK | NONE | SQUARE;
}
}
}
public void initSnake() {
int i, j;
int m, n;
// Create a new snake in the center of the grid and reset cell list.
i = GRID_WIDTH / 2;
j = GRID_HEIGHT / 2;
snake[4].x = i - 2; snake[4].y = j;
snake[3].x = i - 1; snake[3].y = j;
snake[2].x = i - 0; snake[2].y = j;
snake[1].x = i + 1; snake[1].y = j;
snake[0].x = i + 2; snake[0].y = j;
headPtr = 4;
tailPtr = 0;
grid[i - 2][j] = SNAKE | LEFT | SNAKEHEAD;
grid[i - 1][j] = SNAKE | LEFT | SNAKEBODY;
grid[i][j] = SNAKE | LEFT | SNAKEBODY;
grid[i + 1][j] = SNAKE | LEFT | SNAKEBODY;
grid[i + 2][j] = SNAKE | LEFT | SNAKETAIL;
// Clear snake direction.
direction = NONE;
lastDirection = NONE;
// Relocate any mice that were overwritten.
for (m = 0; m < NUM_MICE; m++)
for (n = -2; n <= 2 ; n++)
if (mouse[m].x == i + n && mouse[m].y == j)
initMouse(m);
// Relocate key if overwritten.
if (keyActive)
for (n = -2; n <= 2 ; n++)
if (key.x == i + n && key.y == j)
initKey();
}
public void moveSnake() {
Point pt;
int i, j;
int k;
int c;
int d;
// Lock cursor keys to prevent the current direction from being changed
// until we are done processing it.
lockKeys = true;
// Move snake's head into the next cell based on current direction.
pt = snake[headPtr];
i = pt.x;
j = pt.y;
switch (direction) {
case LEFT:
i--;
break;
case RIGHT:
i++;
break;
case UP:
j--;
break;
case DOWN:
j++;
break;
default:
lockKeys = false;
return;
}
// Unlock cursor keys and save direction.
lockKeys = false;
lastDirection = direction;
// Skip if no direction given.
if (direction == NONE)
return;
// Get the type of the new cell.
c = grid[i][j] & TYPE_MASK;
// Check if we hit a wall or ourselves.
if (c == BLOCK || c == SNAKE) {
if (loaded && sound)
bonkSound.play();
endLife();
return;
}
// Replace current head with the appropriate body part.
d = grid[pt.x][pt.y] & DIR_MASK;
if (d == direction)
grid[pt.x][pt.y] = SNAKE | d | SNAKEBODY;
else if (d == LEFT && direction == UP)
grid[pt.x][pt.y] = SNAKE | direction | SNAKEELB1;
else if (d == UP && direction == RIGHT)
grid[pt.x][pt.y] = SNAKE | direction | SNAKEELB1;
else if (d == RIGHT && direction == DOWN)
grid[pt.x][pt.y] = SNAKE | direction | SNAKEELB1;
else if (d == DOWN && direction == LEFT)
grid[pt.x][pt.y] = SNAKE | direction | SNAKEELB1;
else if (d == UP && direction == LEFT)
grid[pt.x][pt.y] = SNAKE | direction | SNAKEELB2;
else if (d == LEFT && direction == DOWN)
grid[pt.x][pt.y] = SNAKE | direction | SNAKEELB2;
else if (d == DOWN && direction == RIGHT)
grid[pt.x][pt.y] = SNAKE | direction | SNAKEELB2;
else if (d == RIGHT && direction == UP)
grid[pt.x][pt.y] = SNAKE | direction | SNAKEELB2;
// Change the new cell to a snake's head and set it in the cell list.
grid[i][j] = SNAKE | direction | SNAKEHEAD;
if (++headPtr >= snake.length)
headPtr = 0;
snake[headPtr].x = i;
snake[headPtr].y = j;
// If we got a mouse, bump the score and create a new one. Otherwise,
// move the tail.
if (c == MOUSE) {
score += MOUSE_POINTS;
if (loaded && sound)
munchSound.play();
for (k = 0; k < NUM_MICE; k++)
if (mouse[k].x == i && mouse[k].y == j)
initMouse(k);
miceEaten++;
}
else {
pt = snake[tailPtr];
grid[pt.x][pt.y] = EMPTY & NONE & SQUARE;
if (++tailPtr >= snake.length)
tailPtr = 0;
pt = snake[tailPtr];
d = grid[pt.x][pt.y] & DIR_MASK;
grid[pt.x][pt.y] = SNAKE | d | SNAKETAIL;
}
// Check if we got the key. If so, end the current level.
if (c == KEY) {
score += LEVEL_POINTS;
if (loaded && sound)
advanceSound.play();
endLevel();
}
}
public void killSnake() {
Point pt;
int n;
// Remove snake from the grid.
n = headPtr + 1;
if (n >= snake.length)
n = 0;
while(tailPtr != n) {
pt = snake[tailPtr];
grid[pt.x][pt.y] = EMPTY | NONE | SQUARE;
if (++tailPtr >= snake.length)
tailPtr = 0;
}
}
public void initMouse(int n) {
int i, j;
int d;
// Find an empty cell.
do {
i = (int) (Math.random() * GRID_WIDTH);
j = (int) (Math.random() * GRID_HEIGHT);
} while ((grid[i][j] & TYPE_MASK) != EMPTY);
// Get a random direction.
d = (int) (Math.random() * 4) + 1;
d <<= 8;
// Save mouse position.
mouse[n].x = i;
mouse[n].y = j;
// Set the cell with mouse data.
grid[i][j] = MOUSE | d | MOUSEBODY;
}
public void moveMouse(int n) {
int i, j;
int d;
int m;
// Skip move at random.
if (Math.random() > 0.25)
return;
// Skip move if mouse is dead.
if (mouse[n].x == -1 || mouse[n].y == -1)
return;
// Toss in a random squeak.
if (loaded && sound && Math.random() > 0.975)
squeakSound.play();
// Get a random direction.
d = (int) (Math.random() * 5);
d <<= 8;
// Don't allow a reversal of direction.
m = grid[mouse[n].x][mouse[n].y] & DIR_MASK;
if ((m == LEFT && d == RIGHT) ||
(m == RIGHT && d == LEFT) ||
(m == UP && d == DOWN) ||
(m == DOWN && d == UP))
return;
i = mouse[n].x;
j = mouse[n].y;
switch (d) {
case LEFT:
i--;
break;
case RIGHT:
i++;
break;
case UP:
j--;
break;
case DOWN:
j++;
break;
default:
return;
}
// See if the new cell is empty. If not, skip move.
if ((grid[i][j] & TYPE_MASK) != EMPTY)
return;
// Clear mouse from old cell and move to the new one.
grid[mouse[n].x][mouse[n].y] = EMPTY | NONE | SQUARE;
mouse[n].x = i;
mouse[n].y = j;
grid[i][j] = MOUSE | d | MOUSEBODY;
}
public void killMouse(int n) {
// Clear mouse from grid and set coordinates to (-1, -1) so we know it is
// dead.
grid[mouse[n].x][mouse[n].y] = EMPTY | NONE | SQUARE;
mouse[n].x = -1;
mouse[n].y = -1;
}
public void initKey() {
int i, j;
// Find an empty cell.
do {
i = (int) (Math.random() * GRID_WIDTH);
j = (int) (Math.random() * GRID_HEIGHT);
} while ((grid[i][j] & TYPE_MASK) != EMPTY);
// Save key position.
key.x = i;
key.y = j;
// Set the cell with key data and set the flag to show it's been added.
grid[i][j] = KEY | NONE | KEYSHAPE;
keyActive = true;
}
public Polygon translate(Polygon p, int dx, int dy) {
Polygon polygon;
int i;
// Returns the polygon created by translating the given shape.
polygon = new Polygon();
for (i = 0; i < p.npoints; i++)
polygon.addPoint(p.xpoints[i] + dx, p.ypoints[i] + dy);
return polygon;
}
public Polygon rotate(Polygon p, int d) {
Polygon polygon;
int i;
// Returns the polygon created by rotating the given shape in 90 deg. increments.
polygon = new Polygon();
for (i = 0; i < p.npoints; i++)
switch (d) {
case LEFT:
polygon.addPoint(p.ypoints[i], (GRID_SIZE - 1) - p.xpoints[i]);
break;
case RIGHT:
polygon.addPoint((GRID_SIZE - 1) - p.ypoints[i], p.xpoints[i]);
break;
case DOWN:
polygon.addPoint((GRID_SIZE - 1) - p.xpoints[i], (GRID_SIZE - 1) - p.ypoints[i]);
break;
default:
polygon.addPoint(p.xpoints[i], p.ypoints[i]);
break;
}
return polygon;
}
public Polygon mirror(Polygon p) {
Polygon polygon;
int i;
// Returns the polygon created by mirroring the given shape.
polygon = new Polygon();
for (i = 0; i < p.npoints; i++)
polygon.addPoint((GRID_SIZE - 1) - p.xpoints[i], p.ypoints[i]);
return polygon;
}
public Color fade(Color s, Color e, double pct) {
int r, g, b;
// Fade the starting color to the ending color by the given percentage.
if (pct < 0.0)
return e;
if (pct > 1.0)
return s;
r = e.getRed() + (int) Math.round(pct * (s.getRed() - e.getRed()));
g = e.getGreen() + (int) Math.round(pct * (s.getGreen() - e.getGreen()));
b = e.getBlue() + (int) Math.round(pct * (s.getBlue() - e.getBlue()));
return(new Color(r, g, b));
}
public void paint(Graphics g) {
update(g);
}
public void update(Graphics g) {
Dimension d = size();
int width, height;
int xOff, yOff;
int i, j;
int m;
int n;
Polygon p;
String s;
// Create the offscreen graphics context, if no good one exists.
if (offGraphics == null || d.width != offDimension.width || d.height != offDimension.height) {
offDimension = d;
offImage = createImage(d.width, d.height);
offGraphics = offImage.getGraphics();
}
// Fill in applet background.
offGraphics.setColor(bgColor);
offGraphics.fillRect(0, 0, d.width, d.height);
// Center game area.
width = GRID_WIDTH * GRID_SIZE;
height = GRID_HEIGHT * GRID_SIZE;
xOff = (d.width - width) / 2;
yOff = (d.height - (height + 2 * fontHeight)) / 2;
offGraphics.translate(xOff, yOff);
// Fill in playing field.
if (gameState == LEVEL)
offGraphics.setColor(fade(fieldColor, bgColor, (double) levelCounter / (double) LEVEL_COUNT));
else
offGraphics.setColor(fieldColor);
offGraphics.fillRect(0, 0, GRID_WIDTH * GRID_SIZE, GRID_HEIGHT * GRID_SIZE);
// Fill in each grid cell with the appropriate shape.
for (i = 0; i < GRID_WIDTH; i++)
for (j = 0; j < GRID_HEIGHT; j++)
switch (grid[i][j] & TYPE_MASK) {
case EMPTY:
break;
case BLOCK:
if (gameState == LEVEL)
offGraphics.setColor(fade(blockColor, bgColor, (double) levelCounter / (double) LEVEL_COUNT));
else
offGraphics.setColor(blockColor);
offGraphics.fillRect(i * GRID_SIZE, j * GRID_SIZE, GRID_SIZE, GRID_SIZE);
offGraphics.setColor(bgColor);
offGraphics.drawRect(i * GRID_SIZE, j * GRID_SIZE, GRID_SIZE, GRID_SIZE);
break;
case SNAKE:
n = grid[i][j] & SHAPE_MASK;
switch (n) {
case SNAKEHEAD:
p = snakeHead;
break;
case SNAKEBODY:
p = snakeBody;
break;
case SNAKEELB1:
p = snakeElb1;
break;
case SNAKEELB2:
p = snakeElb2;
break;
case SNAKETAIL:
p = snakeTail;
break;
default:
p = snakeHead;
break;
}
p = translate(rotate(p, grid[i][j] & DIR_MASK), i * GRID_SIZE, j * GRID_SIZE);
if (gameState == LEVEL)
offGraphics.setColor(fade(snakeColor, bgColor, (double) levelCounter / (double) LEVEL_COUNT));
else if (gameState == END || gameState == OVER)
offGraphics.setColor(fade(snakeColor, fieldColor, (double) endCounter / (double) END_COUNT));
else
offGraphics.setColor(snakeColor);
offGraphics.fillPolygon(p);
offGraphics.drawPolygon(p);
offGraphics.drawLine(p.xpoints[p.npoints - 1], p.ypoints[p.npoints - 1], p.xpoints[0], p.ypoints[0]);
if (gameState == END || gameState == OVER)
offGraphics.setColor(fade(bgColor, fieldColor, (double) endCounter / (double) END_COUNT));
else
offGraphics.setColor(bgColor);
if (n == SNAKEHEAD || n == SNAKETAIL)
for (m = 0; m < p.npoints - 1; m++)
offGraphics.drawLine(p.xpoints[m], p.ypoints[m], p.xpoints[m + 1], p.ypoints[m + 1]);
if (n == SNAKEBODY) {
offGraphics.drawLine(p.xpoints[0], p.ypoints[0], p.xpoints[1], p.ypoints[1]);
offGraphics.drawLine(p.xpoints[2], p.ypoints[2], p.xpoints[3], p.ypoints[3]);
}
if (n == SNAKEELB1 || n == SNAKEELB2) {
offGraphics.drawLine(p.xpoints[0], p.ypoints[0], p.xpoints[1], p.ypoints[1]);
offGraphics.drawLine(p.xpoints[1], p.ypoints[1], p.xpoints[2], p.ypoints[2]);
offGraphics.drawLine(p.xpoints[3], p.ypoints[3], p.xpoints[4], p.ypoints[4]);
offGraphics.drawLine(p.xpoints[4], p.ypoints[4], p.xpoints[5], p.ypoints[5]);
offGraphics.drawLine(p.xpoints[5], p.ypoints[5], p.xpoints[6], p.ypoints[6]);
}
break;
case MOUSE:
if (gameState == LEVEL)
offGraphics.setColor(fade(mouseColor, bgColor, (double) levelCounter / (double) LEVEL_COUNT));
else
offGraphics.setColor(mouseColor);
p = translate(rotate(mouseBody, grid[i][j] & DIR_MASK), i * GRID_SIZE, j * GRID_SIZE);
offGraphics.fillPolygon(p);
offGraphics.setColor(bgColor);
offGraphics.drawPolygon(p);
offGraphics.drawLine(p.xpoints[p.npoints - 1], p.ypoints[p.npoints - 1], p.xpoints[0], p.ypoints[0]);
break;
case KEY:
p = translate(rotate(keyShape, grid[i][j] & DIR_MASK), i * GRID_SIZE, j * GRID_SIZE);
offGraphics.setColor(keyColor);
offGraphics.fillPolygon(p);
offGraphics.setColor(bgColor);
offGraphics.drawPolygon(p);
offGraphics.drawLine(p.xpoints[p.npoints - 1], p.ypoints[p.npoints - 1], p.xpoints[0], p.ypoints[0]);
break;
default:
break;
}
// Outline playing field.
offGraphics.setColor(fieldColor);
offGraphics.drawRect(0, 0, GRID_WIDTH * GRID_SIZE, GRID_HEIGHT * GRID_SIZE - 1);
// Display status and messages.
offGraphics.setFont(font);
offGraphics.setColor(fieldColor);
i = height - 1;
j = height + 3 * fontHeight / 2;
offGraphics.drawRect(0, i, width, 2 * fontHeight);
offGraphics.setColor(fgColor);
s = "Score: " + score;
offGraphics.drawString(s, fontWidth, j);
s = "Level: " + levelTotal;
offGraphics.drawString(s, (width - fm.stringWidth(s)) / 4, j);
s = "Lives: " + lives;
offGraphics.drawString(s, 3 * (width - fm.stringWidth(s)) / 4, j);
s = "High: " + highScore;
offGraphics.drawString(s, width - (fontWidth + fm.stringWidth(s)), j);
if (paused) {
s = "Paused";
offGraphics.drawString(s, (width - fm.stringWidth(s)) / 2, j);
}
else if (!sound) {
s = "Muted";
offGraphics.drawString(s, (width - fm.stringWidth(s)) / 2, j);
}
if (gameState == INIT || gameState == OVER) {
offGraphics.setColor(bgColor);
s = "Snake Pit";
offGraphics.drawString(s, (width - fm.stringWidth(s)) / 2 + 1, height / 3 + fontHeight + 1);
s = "Copyright 1998 by Mike Hall";
offGraphics.drawString(s, (width - fm.stringWidth(s)) / 2 + 1, height / 3 + 2 * fontHeight + 1);
offGraphics.setColor(fgColor);
s = "Snake Pit";
offGraphics.drawString(s, (width - fm.stringWidth(s)) / 2, height / 3 + fontHeight);
s = "Copyright 1998 by Mike Hall";
offGraphics.drawString(s, (width - fm.stringWidth(s)) / 2, height / 3 + 2 * fontHeight);
offGraphics.setColor(fgColor);
if (!loaded)
s = "Loading sounds...";
else
s = "Game Over - 'S' to Start";
offGraphics.setColor(bgColor);
offGraphics.drawString(s, (width - fm.stringWidth(s)) / 2 + 1, 2 * height / 3 + 1);
offGraphics.setColor(fgColor);
offGraphics.drawString(s, (width - fm.stringWidth(s)) / 2, 2 * height / 3);
}
if (gameState == LEVEL) {
s = "Advancing to Level " + (levelTotal + 1);
offGraphics.setColor(bgColor);
offGraphics.drawString(s, (width - fm.stringWidth(s)) / 2 + 1, height / 2 + 1);
offGraphics.setColor(fgColor);
offGraphics.drawString(s, (width - fm.stringWidth(s)) / 2, height / 2);
}
// Copy the off screen buffer to the screen.
offGraphics.translate(-xOff, -yOff);
g.drawImage(offImage, 0, 0, this);
}
}
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