Add asteroids game

Source code is the same as upstream, aside from a header added.

Author: jart

examples/asteroids.c

@@ -0,0 +1,346 @@
+// -*- mode:c; indent-tabs-mode:nil; c-basic-offset:4 -*-
+// vi: set et ft=c ts=4 sts=4 sw=4 fenc=utf-8
+
+// asteroids by tsotchke
+// https://github.com/tsotchke/asteroids
+
+// clang-format off
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+#include <time.h>
+#include <unistd.h>
+#include <termios.h>
+#include <sys/select.h>
+
+#define SCREEN_WIDTH 80
+#define SCREEN_HEIGHT 24
+#define MAX_ASTEROIDS 5
+#define MAX_BULLETS 5
+
+typedef struct {
+    float x, y;
+} Vector2;
+
+typedef struct {
+    Vector2 position;
+    Vector2 velocity;
+    float angle;
+    float radius;
+} GameObject;
+
+GameObject spaceship;
+GameObject asteroids[MAX_ASTEROIDS];
+GameObject bullets[MAX_BULLETS];
+
+int score = 0;
+time_t startTime;
+int isGameOver = 0;
+int finalTime = 0; // To store final time at game over
+char display[SCREEN_HEIGHT][SCREEN_WIDTH];
+
+// Function to clear the screen buffer
+void clearDisplay() {
+    memset(display, ' ', sizeof(display));
+}
+
+// Function to draw a pixel on the screen
+void drawPixel(int x, int y) {
+    if (x >= 0 && x < SCREEN_WIDTH && y >= 0 && y < SCREEN_HEIGHT) {
+        display[y][x] = '*';
+    }
+}
+
+// Function to draw a line using Bresenham's algorithm
+void drawLine(int x1, int y1, int x2, int y2) {
+    int dx = abs(x2 - x1), sx = (x1 < x2) ? 1 : -1;
+    int dy = -abs(y2 - y1), sy = (y1 < y2) ? 1 : -1;
+    int error = dx + dy, e2;
+
+    while (1) {
+        drawPixel(x1, y1);
+        if (x1 == x2 && y1 == y2) break;
+        e2 = 2 * error;
+        if (e2 >= dy) { error += dy; x1 += sx; }
+        if (e2 <= dx) { error += dx; y1 += sy; }
+    }
+}
+
+// Function to draw a circle
+void drawCircle(int centerX, int centerY, int radius) {
+    int x = radius - 1, y = 0, dx = 1, dy = 1, err = dx - (radius << 1);
+    while (x >= y) {
+        drawPixel(centerX + x, centerY + y);
+        drawPixel(centerX + y, centerY + x);
+        drawPixel(centerX - y, centerY + x);
+        drawPixel(centerX - x, centerY + y);
+        drawPixel(centerX - x, centerY - y);
+        drawPixel(centerX - y, centerY - x);
+        drawPixel(centerX + y, centerY - x);
+        drawPixel(centerX + x, centerY - y);
+
+        if (err <= 0) {
+            y++;
+            err += dy;
+            dy += 2;
+        }
+        if (err > 0) {
+            x--;
+            dx += 2;
+            err += dx - (radius << 1);
+        }
+    }
+}
+
+// Initialize a game object
+void initializeGameObject(GameObject *obj, float x, float y, float angle, float radius) {
+    obj->position = (Vector2){x, y};
+    obj->velocity = (Vector2){0, 0};
+    obj->angle = angle;
+    obj->radius = radius;
+}
+
+// Wrap position of the spaceship and asteroids within screen bounds
+void wrapPosition(Vector2 *pos) {
+    if (pos->x < 0) pos->x = SCREEN_WIDTH - 1;
+    if (pos->x >= SCREEN_WIDTH) pos->x = 0;
+    if (pos->y < 0) pos->y = SCREEN_HEIGHT - 1;
+    if (pos->y >= SCREEN_HEIGHT) pos->y = 0;
+}
+
+// Check if two game objects are colliding
+int checkCollision(GameObject *a, GameObject *b) {
+    float deltaX = a->position.x - b->position.x;
+    float deltaY = a->position.y - b->position.y;
+    return sqrt(deltaX * deltaX + deltaY * deltaY) < (a->radius + b->radius);
+}
+
+// Initialize game state
+void initGame() {
+    score = 0; // Reset the score
+    initializeGameObject(&spaceship, SCREEN_WIDTH / 2, SCREEN_HEIGHT / 2, 0, 2);
+
+    for (int i = 0; i < MAX_ASTEROIDS; i++) {
+        initializeGameObject(&asteroids[i],
+            rand() % SCREEN_WIDTH,
+            rand() % SCREEN_HEIGHT,
+            0,
+            2 + rand() % 3);
+        asteroids[i].velocity.x = ((float)rand() / RAND_MAX) * 2 - 1;
+        asteroids[i].velocity.y = ((float)rand() / RAND_MAX) * 2 - 1;
+    }
+
+    for (int i = 0; i < MAX_BULLETS; i++) {
+        bullets[i].position.x = -1; // Mark bullet as inactive
+        bullets[i].position.y = -1;
+    }
+
+    startTime = time(NULL);
+    isGameOver = 0;
+    finalTime = 0; // Reset final time
+}
+
+// Draw the spaceship on the screen
+void drawSpaceship() {
+    int x = (int)spaceship.position.x;
+    int y = (int)spaceship.position.y;
+    int size = 3;
+
+    float cosAngle = cos(spaceship.angle);
+    float sinAngle = sin(spaceship.angle);
+
+    int x1 = x + size * cosAngle;
+    int y1 = y + size * sinAngle;
+    int x2 = x + size * cos(spaceship.angle + 2.5);
+    int y2 = y + size * sin(spaceship.angle + 2.5);
+    int x3 = x + size * cos(spaceship.angle - 2.5);
+    int y3 = y + size * sin(spaceship.angle - 2.5);
+
+    drawLine(x1, y1, x2, y2);
+    drawLine(x2, y2, x3, y3);
+    drawLine(x3, y3, x1, y1);
+}
+
+// Draw all entities on the screen
+void drawEntities(GameObject *entities, int count, void (*drawFunc)(GameObject *)) {
+    for (int i = 0; i < count; i++) {
+        drawFunc(&entities[i]);
+    }
+}
+
+// Draw a bullet on the screen
+void drawBullet(GameObject *bullet) { // Changed to non-const
+    if (bullet->position.x >= 0) {
+        drawPixel((int)bullet->position.x, (int)bullet->position.y);
+    }
+}
+
+// Draw an asteroid on the screen
+void drawAsteroid(GameObject *asteroid) { // Changed to non-const
+    drawCircle((int)asteroid->position.x, (int)asteroid->position.y, (int)asteroid->radius);
+}
+
+// Refresh the display
+void updateDisplay() {
+    clearDisplay();
+    if (!isGameOver) {
+        drawSpaceship();
+        drawEntities(asteroids, MAX_ASTEROIDS, drawAsteroid);
+        drawEntities(bullets, MAX_BULLETS, drawBullet);
+    }
+
+    // Print the screen buffer
+    printf("\033[H");
+    for (int y = 0; y < SCREEN_HEIGHT; y++) {
+        for (int x = 0; x < SCREEN_WIDTH; x++) {
+            putchar(display[y][x]);
+        }
+        putchar('\n');
+    }
+    
+    // Display score and elapsed time
+    time_t currentTime = time(NULL);
+    int elapsedTime = isGameOver ? finalTime : (currentTime - startTime);
+    printf("Score: %d | Time: %02d:%02d | %s\n", score, elapsedTime / 60, elapsedTime % 60, isGameOver ? "Game Over!" : "           ");
+}
+
+// Update the position of game objects
+void updateGameObject(GameObject *obj, int isBullet) {
+    obj->position.x += obj->velocity.x;
+    obj->position.y += obj->velocity.y;
+
+    // If it's a bullet, check if it's out of bounds
+    if (isBullet) {
+        if (obj->position.x < 0 || obj->position.x >= SCREEN_WIDTH || obj->position.y < 0 || obj->position.y >= SCREEN_HEIGHT) {
+            obj->position.x = -1; // Deactivate bullet
+            obj->position.y = -1;
+        }
+    } else {
+        wrapPosition(&obj->position);
+    }
+}
+
+// Update the game state
+void updateGame() {
+    if (isGameOver) return; 
+
+    // Update spaceship and apply friction
+    updateGameObject(&spaceship, 0); // 0 indicates it's not a bullet
+    spaceship.velocity.x *= 0.98;
+    spaceship.velocity.y *= 0.98;
+
+    // Move asteroids and check for collisions
+    for (int i = 0; i < MAX_ASTEROIDS; i++) {
+        updateGameObject(&asteroids[i], 0);
+        if (checkCollision(&spaceship, &asteroids[i])) {
+            isGameOver = 1;
+            finalTime = time(NULL) - startTime;
+            return;
+        }
+    }
+
+    // Update bullet positions
+    for (int i = 0; i < MAX_BULLETS; i++) {
+        if (bullets[i].position.x >= 0) {
+            updateGameObject(&bullets[i], 1); // 1 indicates it's a bullet
+        }
+    }
+
+    // Check for bullet collisions with asteroids
+    for (int i = 0; i < MAX_BULLETS; i++) {
+        if (bullets[i].position.x >= 0) {
+            for (int j = 0; j < MAX_ASTEROIDS; j++) {
+                if (checkCollision(&bullets[i], &asteroids[j])) {
+                    bullets[i].position.x = -1; // Deactivate bullet
+                    bullets[i].position.y = -1;
+                    asteroids[j].position.x = rand() % SCREEN_WIDTH;
+                    asteroids[j].position.y = rand() % SCREEN_HEIGHT;
+                    score += 100;
+                }
+            }
+        }
+    }
+}
+
+// Fire a bullet
+void shootBullet() {
+    for (int i = 0; i < MAX_BULLETS; i++) {
+        if (bullets[i].position.x < 0) {
+            bullets[i].position = spaceship.position;
+            bullets[i].velocity.x = cos(spaceship.angle) * 2;
+            bullets[i].velocity.y = sin(spaceship.angle) * 2;
+            break;
+        }
+    }
+}
+
+// Check if a key was hit
+int isKeyHit() {
+    struct timeval tv = { 0L, 0L };
+    fd_set fds;
+    FD_ZERO(&fds);
+    FD_SET(0, &fds);
+    return select(1, &fds, NULL, NULL, &tv);
+}
+
+// Configure terminal settings
+void configureTerminal(struct termios *old_tio, struct termios *new_tio) {
+    tcgetattr(STDIN_FILENO, old_tio);
+    *new_tio = *old_tio;
+    new_tio->c_lflag &= (~ICANON & ~ECHO);
+    tcsetattr(STDIN_FILENO, TCSANOW, new_tio);
+}
+
+// Restore terminal settings
+void restoreTerminal(struct termios *old_tio) {
+    tcsetattr(STDIN_FILENO, TCSANOW, old_tio);
+}
+
+// Main game loop
+int main() {
+    srand(time(NULL)); // Seed the random number generator
+    initGame(); // Initialize the game state
+
+    struct termios old_tio, new_tio;
+    configureTerminal(&old_tio, &new_tio);
+
+    printf("\033[?25l");  // Hide the cursor
+
+    while (1) {
+        if (isKeyHit()) {
+            char input = getchar();
+            if (input == 27) {  // ESC key
+                if (getchar() == '[') {  // Handle arrow keys
+                    switch (getchar()) {
+                        case 'A':  // Up arrow
+                            spaceship.velocity.x += cos(spaceship.angle) * 0.2;
+                            spaceship.velocity.y += sin(spaceship.angle) * 0.2;
+                            break;
+                        case 'B':  // Down arrow
+                            spaceship.velocity.x -= cos(spaceship.angle) * 0.2;
+                            spaceship.velocity.y -= sin(spaceship.angle) * 0.2;
+                            break;
+                        case 'D': spaceship.angle -= 0.2; break;  // Left arrow
+                        case 'C': spaceship.angle += 0.2; break;  // Right arrow
+                    }
+                }
+            } else if (input == ' ') {
+                shootBullet(); // Fire a bullet
+            } else if (input == 'q') {
+                break; // Quit the game
+            } else if (input == 'r' && isGameOver) {
+                initGame(); // Restart the game
+            }
+        }
+
+        updateGame(); // Update game state
+        updateDisplay(); // Refresh the display
+        usleep(50000);  // Wait for 50ms (20 FPS)
+    }
+
+    printf("\033[?25h");  // Show the cursor
+    restoreTerminal(&old_tio); // Restore terminal settings
+    return 0;
+}