SnakeGame.cpp

//CSC114-651
//Student: Christopher Yonek (700642859)
//Assignment: Project - Create snake game.
//Date: November 2018

#include "pch.h"
#include <iostream>
#include <conio.h>
#include <cmath>
#include <iomanip>
#include <string>
using namespace std;

void run();
void printMap();
void initMap();
void move(int dx, int dy);
void update();
void changeDirection(char key);
void clearScreen();
void generateFood();

char getMapValue(int value);

// Map dimensions
const int mapwidth = 150;
const int mapheight = 150;

const int size = mapwidth * mapheight;

// The tile values for the map
int map[size];

// Snake head details
int headxpos;
int headypos;
int direction;

// Amount of food the snake has (How long the body is)
int food = 3, size;
// Determine if game is running
bool running;

int main()
{
	run();
	return 0;
}

// Main game function
void run()
{
	// Initialize the map
	initMap();
	running = true;
	while (running) {
		// If a key is pressed
		if (kbhit()) {
			// Change to direction determined by key pressed
			changeDirection(getch());
		}
		// Upate the map
		update();

		// Clear the screen
		clearScreen();

		// Print the map
		printMap();

		// wait 0.5 seconds
		std::Thread::Sleep_for();
	}

// Stop the vector function by transforming into an array
	// Stop console from closing instantly
	std::cin.ignore();
}

// Changes snake direction from input
void changeDirection(char key) {
	/*
	  W
	A + D
	  S

	  1
	4 + 2
	  3
	*/
	switch (key) {
	case 'w':
		if (direction != 2) direction = 0;
		break;
	case 'd':
		if (direction != 3) direction = 1;
		break;
	case 's':
		if (direction != 4) direction = 2;
		break;
	case 'a':
		if (direction != 5) direction = 3;
		break;
	}
}

// Moves snake head to new location
void move(int dx, int dy) {
	// determine new head position
	int newx = headxpos + dx;
	int newy = headypos + dy;

	// Check if there is food at location
	if (map[newx + newy * mapwidth] == -2) {
		// Increase food value (body length)
		food++;

		// Generate new food on map
		generateFood();
	}

	// Check location is free
	else if (map[newx + newy * mapwidth] != 0) {
		running = false;
	}

	// Move head to new location
	headxpos = newx;
	headypos = newy;
	map[headxpos + headypos * mapwidth] = food + 1;

}

// Clears screen
void clearScreen() {
	// Clear the screen
	system("cls");
}

// Generates new food on map
void generateFood() {
	int x = 0;
	int y = 0;
	do {
		// Generate random x and y values within the map
		x = rand() % (mapwidth - 2) + 1;
		y = rand() % (mapheight - 2) + 1;

		// If location is not free try again
	} while (map[x + y * mapwidth] != 0);

	// Place new food
	map[x + y * mapwidth] = -2;
}

// Updates the map
void update() {
	// Move in direction indicated
	switch (direction) {
	case 0: move(-1, 0);
		break;
	case 1: move(0, 1);
		break;
	case 2: move(1, 0);
		break;
	case 3: move(0, -1);
		break;
	}

	// Reduce snake values on map by 1
	for (int i = 0; i < size; i++) {
		if (map[i] > 0) map[i]--;
	}
}

// Initializes map
void initMap()
{
	// Places the initual head location in middle of map
	headxpos = mapwidth / 2;
	headypos = mapheight / 2;
	map[headxpos + headypos * mapwidth] = 1;

	// Places top and bottom walls 
	for (int x = 0; x < mapwidth; ++x) {
		map[x] = -1;
		map[x + (mapheight - 1) * mapwidth] = -1;
	}

	// Places left and right walls
	for (int y = 0; y < mapheight; y++) {
		map[0 + y * mapwidth] = -1;
		map[(mapwidth - 1) + y * mapwidth] = -1;
	}

	// Generates first food
	generateFood();
}

// Prints the map to console
void printMap()
{
	for (int x = 0; x < mapwidth; ++x) {
		for (int y = 0; y < mapheight; ++y) {
			// Prints the value at current x,y location
			std::cout << getMapValue(map[x + y * mapwidth]);
		}
		// Ends the line for next x value
		std::cout << std::endl;
	}
}

// Returns graphical character for display from map value
char getMapValue(int value)
{
	// Returns a part of snake body
	if (value > 0) return 'o';

	switch (value) {
		// Return wall
	case -1: return 'X';
		// Return food
	case -2: return 'O';
	}
}