Snake and Mouse game and this time, you're the mouse! Full C Source Code

snake_n_mouse.c

// Snake and Mouse game, you're the mouse. Eat cheese to get points and watch out for the snake!
// Written by naezith, you can use/change the code however you want.

#include <stdio.h>
#include <conio.h>
#include <windows.h>
#include <math.h>
#include <time.h>

#define MAP_WIDTH 20
#define MAP_HEIGHT 20
#define SNAKE_SIZE 8

void init();
void input();
void draw();
void logic();
int onPlayer(int, int);
int onCheese(int, int);
int onSnake(int, int);
void spawnCheese();
void spawnSnake();
int rand_i();
int rand_j();

typedef struct S_COORD { int i, j; } MAP_COORD;

// Game variables
unsigned frameNumber = 0;
int paused = 0;

// Snake variables
float snake_pos_i, snake_pos_j, snake_speed = 0.15f;
MAP_COORD snake_body[SNAKE_SIZE];

// Player and cheese variables
int player_score, highest_score = 0;
MAP_COORD player_pos, cheese_pos;

// Returns random position on the level
int rand_i() { return rand() % MAP_HEIGHT; }
int rand_j() { return rand() % MAP_WIDTH; }

// Check if position is on player
int onPlayer(int i, int j) { return i == player_pos.i && j == player_pos.j; }

// Check if position is on cheese
int onCheese(int i, int j) { return i == cheese_pos.i && j == cheese_pos.j; }

// Check if position is on snake, if yes, return the body part number
int onSnake(int i, int j) {
	int k;
	for (k = 0; k < SNAKE_SIZE; ++k) if (i == snake_body[k].i && j == snake_body[k].j) return k + 1;
	return 0;
}

void spawnCheese() {
	// Find a proper random place for cheese: not on another cheese, not on the player and not on the snake
	int i, j;
	do { i = rand_i(); j = rand_j();
	} while (onCheese(i, j) || onPlayer(i, j) || onSnake(i, j) == 1);

	// Then place it there
	cheese_pos.i = i;
	cheese_pos.j = j;
}

void spawnSnake() {
	// Put snake to the top left
	int i;
	for (i = 0; i < SNAKE_SIZE; ++i) {
		snake_body[i].i = 0;
		snake_body[i].j = i;
	}

	// Set his head position to float position holder
	snake_pos_i = (float)snake_body[SNAKE_SIZE-1].i;
	snake_pos_j = (float)snake_body[SNAKE_SIZE-1].j;
}

void moveSnake() {
	MAP_COORD head = snake_body[SNAKE_SIZE-1], new_pos;

	// Calculate the distance vector
	float d_i = (float)(player_pos.i - head.i);
	float d_j = (float)(player_pos.j - head.j);

	// Calculate the length of the distance vector
	float mag = sqrtf(d_i*d_i + d_j*d_j);

	// Add the unit vector to our position
	snake_pos_i += snake_speed * d_i / mag;
	snake_pos_j += snake_speed * d_j / mag;

	// Iterate the snake body parts when position is really changed as integer
	new_pos.i = (int)snake_pos_i;
	new_pos.j = (int)snake_pos_j;
	if (new_pos.i != head.i || new_pos.j != head.j) {
		int k;
		for (k = 0; k < SNAKE_SIZE-1; ++k) snake_body[k] = snake_body[k + 1];
		snake_body[k] = new_pos;
	}
}

void main(void) {
	int fps = 60; // 30 to 60 fps is common for rendering graphics.
	int sleepTime = 1000 / fps;	// To get 60 fps, we have to redraw graphics every 1000/60=17 miliseconds
	srand((unsigned int)time(0));

	init(); // Do your initialization before the infinite loop starts.

	// This is the structure used in programming most games.
	// An infinite loop is run with the game logic and graphics being updated at each iteration.
	while (1) {
		// Check if there is any input, update your variables accordingly.
		input();

		// Do not refresh graphics when paused, it causes unnecessary flicker.
		if (paused == 0) {
			// Refresh graphics.
			draw();

			// Update variables accordingly.
			logic();

			// At each iteration, we sleep for a predetermined amount of time.
			// There are better ways of doing this (multi-threading).
			Sleep(sleepTime);
		}
	}
}

void init() {
	// Stop the game
	paused = 1;

	// Reset current score
	player_score = 0;

	// Put player in a safe field
	player_pos.i = (MAP_HEIGHT + rand_i()) / 2;
	player_pos.j = rand_j();

	spawnSnake();
	spawnCheese();
	draw();
}

void input() {
	char input;

	// _kbhit() checks if there is a character in the buffer, i.e. if you hit any buttons during Sleep().
	if (_kbhit()) {
		// Since a character is already in the buffer, it is loaded to the variable instantly.
		// In other words, this getch() does not stall the program and wait for your response.
		input = _getch();

		// Pause
		if (input == 'p') paused = !paused;
		// Exit
		else if (input == 'x') exit(0);
		// Move up
		else if (input == 'w' && player_pos.i > 0) --player_pos.i;
		// Move down
		else if (input == 's' && player_pos.i + 1 < MAP_HEIGHT) ++player_pos.i;
		// Move left
		else if (input == 'a' && player_pos.j > 0) --player_pos.j;
		// Move right
		else if (input == 'd' && player_pos.j + 1 < MAP_WIDTH) ++player_pos.j;
		// Resume the game if key is not p
		if (input != 'p') paused = 0;
	}
}

// This is where the magic happens. You should update game related variables here
char curr_color[1] = "F"; // Console start color
void logic() {
	frameNumber++;

	// Eat cheese
	if (onCheese(player_pos.i, player_pos.j)) {
        spawnCheese();
		if (++player_score > highest_score) highest_score = player_score;
	}

    moveSnake();

	// Snake hits player, restart.
	if (onSnake(player_pos.i, player_pos.j)) init();

	// Change console color for fun
	if (frameNumber % 5 == 0) {
		char color[9] = "color 0";
		strcat_s(color, 9, curr_color);
		system(color);

		// Cycle colors F to A
		if (curr_color[0] == 'A') curr_color[0] = 'F';
		else --curr_color[0];
	}
}


// Note that we have to redraw the entire image
// This is the case for all practical graphics engines.
void draw() {
	int i, j;

	// Clears the command line, note that this is platform specific, i.e. will not work on UNIX etc.
	system("cls");

	printf("\n   #");
	for (i = 0; i < MAP_WIDTH; ++i) printf("=");
	printf("#          Pause(p)   Exit(x)   Move(w, a, s, d)\n");
	for (i = 0; i < MAP_HEIGHT; i++) {
		printf("   |");
		for (j = 0; j < MAP_WIDTH; j++) {
			int is_snake_body_part = onSnake(i, j); // Which part of snake?

			// Print player
			if (onPlayer(i, j)) printf("@");
			// Print Head
			else if (is_snake_body_part == SNAKE_SIZE) printf("%c", 219);
			// Print Body
			else if (is_snake_body_part) printf("%c", is_snake_body_part % 2 == 0 ? 176 : 177);
			// Print Cheese
			else if (onCheese(i, j)) printf("%c", 207);
			// Print Empty field
			else printf(" ");
		}
		printf("|\n");
	}
	printf("   #");
	for (i = 0; i < MAP_WIDTH; ++i) printf("=");
	printf("#          Score : %d  Highest : %d", player_score, highest_score);
}