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// DGDKSnake
// Description: A simple snake game using DarkGDK (www.thegamecreators.com)
// Date: 13/10/2013
// License: GPLv2

// whenever using Dark GDK you must ensure you include the header file
#include "DarkGDK.h"

void DarkGDK ( void )
{
	// setup
	dbSyncOn   ( );
	dbSyncRate ( 60 );
	dbDisableEscapeKey ( );

	// load background
	dbLoadImage ( "backdrop.bmp", 1 );
	dbSprite ( 1, 0, 0, 1 );

	// set image color key (for logo)
	dbSetImageColorKey ( 0, 0, 0 );

	// set initial positions & game info
	int x = 320;
	int y = 240;
	int blockSize = 20;
	int roomWidth = 640;
	int roomHeight = 480;

	int currentTime = dbTimer();
	int direction = 2; // Right: 0, Down: 1, Left: 2, Up: 3
	char buffer [50];

	// snake tail
	int lastPositions [1000][2];
	int currentPos = 0;
	int snakeSize = 10;

	// score counter(s)
	int score = 0;
	int highscore = 0;
	int level = 1;
	int timing = 0;

	// font, size, screenmode
	dbSetTextFont("Arial Black");
	dbSetTextSize(18);
	int screenmode = 0;

	// title screen logo
	dbLoadImage ( "DGDK_Snake.bmp", 2 );
	dbSprite ( 2, 100, 100, 2 );

	// main loop
	while ( LoopGDK ( ) )
	{
		// Title screen
		if (screenmode == 0){
			dbDrawSpritesFirst();
			dbInk(dbRGB(255,255,255),dbRGB(255,255,255));
			dbText(200,250,"Welcome to DGDKSnake!\n\nPress 'S' to begin a new game");

			if (dbScanCode() == 31){
				dbHideSprite(2);
				for (int i=0; i < snakeSize;i++){
					lastPositions[i][0] = NULL;
					lastPositions[i][1] = NULL;
				}
				screenmode = 1;
			}

			if ( dbEscapeKey ( ) ) // Repeating these :-(
				break;
			dbSync ( );
			continue;
		}

		// main timer loop (update snake movement, score, positions etc)
		if (400-(level*10) > 100)
			timing = 400 - (level*10);
		if ((currentTime + timing) <= dbTimer()){
			switch(direction){
				case 0:
					x += blockSize;
					break;
				case 1:
					y += blockSize;
					break;
				case 2:
					x -= blockSize;
					break;
				case 3:
					y -= blockSize;
					break;
			}

			// store positions
			if (currentPos >= snakeSize-2)
				currentPos = 1;
			else
				currentPos += 1;

			// don't store snake head
			if (currentPos > 0){
				lastPositions[currentPos][0] = x;
				lastPositions[currentPos][1] = y;
			}

			// if score reaches multiple of 400 1-up level
			if (score % 400 == 0){
				level += 1;
				snakeSize += 1;
			}
			score += 40;

			// reset timer
			currentTime = dbTimer();
		}

		// user input (arrow keys)
		if (dbRightKey())
			direction = 0;
		if (dbDownKey())
			direction = 1;
		if (dbLeftKey())
			direction = 2;
		if (dbUpKey())
			direction = 3;

		// draw snake
		for (int i=0; i < snakeSize-1; i++)
		{
			dbInk (dbRGB(255,10,10),dbRGB(255,10,10));

			int lastPosX = lastPositions[i][0];
			int lastPosY = lastPositions[i][1];


			if (lastPositions[i][0] != NULL && lastPositions[i][1] != NULL)
				dbBox(lastPosX,lastPosY,lastPosX+blockSize,lastPosY+blockSize);
			if (lastPositions[i][0] != NULL && lastPositions[i][1] != NULL && // Corner cases (edges)
				lastPositions[i][0] < 0)
				dbBox(0,lastPosY,blockSize,lastPosY+blockSize);
			if (lastPositions[i][0] != NULL && lastPositions[i][1] != NULL && // Corner cases (edges)
				lastPositions[i][0] > roomWidth)
				dbBox(0,lastPosY,blockSize,lastPosY+blockSize);
			if (lastPositions[i][0] != NULL && lastPositions[i][1] != NULL && // Corner cases (edges)
				lastPositions[i][1] > roomHeight)
				dbBox(lastPosX,0,lastPosX+blockSize,blockSize);
			if (lastPositions[i][0] != NULL && lastPositions[i][1] != NULL && // Corner cases (edges)
				lastPositions[i][1] < 0)
				dbBox(lastPosX,0,lastPosX+blockSize,blockSize);

			dbInk (dbRGB(0,10,255),dbRGB(0,10,255));
			dbBox(x,y,x+blockSize,y+blockSize);
		}

		// Debug text
		dbInk (dbRGB(255,255,255),dbRGB(255,255,255));

		sprintf (buffer, "Score: %d\nHighscore: %d\nLevel: %d", score, highscore, level);
		dbText(10,10,buffer);

		// leaving room
		if (x < 0 || x > roomWidth-blockSize || y < 0 || y > roomHeight-blockSize)
			dbText(roomWidth/2-80,roomHeight/2,"Leaving the room, bye!");

		// collision is really simple: check against previous positions & reset if found
		for (int j = 0; j < snakeSize-1; j++){
			if (j != currentPos){
				if (lastPositions[j][0] != NULL && lastPositions[j][1] != NULL){
					if (lastPositions[j][0] == x && lastPositions[j][1] == y){
						x = roomWidth/2;
						y = roomHeight/2;
						
						// reset position counter & clear array
						currentPos = 0;
						for (int k = 0; k < snakeSize; k++){
							lastPositions[k][0] = NULL;
							lastPositions[k][1] = NULL;
						}

						// set highscore
						if (score > highscore)
							highscore = score;
						score = 0;
						level = 1;

						// (extra: save/load highscore from text file)
						break;
					}
				}
			}
		}
		
		// check for leaving room
		if (x > roomWidth)
			x = 0;
		if (x < 0)
			x = roomWidth;
		if (y < 0)
			y = roomHeight;
		if (y > roomHeight)
			y = 0;

		// check escape key
		if ( dbEscapeKey ( ) )
			break;

		// update screen contents
		dbSync ( );
	}

	// when escape pressed loop above will break to here

	// delete background
	dbDeleteImage ( 1 );

	// delete logo
	dbDeleteImage( 2 );

	// return back to Windows
	return;
}