/* Copyright (C) 2023 Salvatore Sanfilippo -- All Rights Reserved * See the LICENSE file for information about the license. */ #include #include #include #include #include #include #include #include #include #define TAG "Asteroids" // Used for logging #define DEBUG_MSG 1 #define SCREEN_XRES 128 #define SCREEN_YRES 64 #define GAME_START_LIVES 3 #ifndef PI #define PI 3.14159265358979f #endif /* ============================ Data structures ============================= */ typedef struct Ship { float x, /* Ship x position. */ y, /* Ship y position. */ vx, /* x velocity. */ vy, /* y velocity. */ rot; /* Current rotation. 2*PI full ortation. */ } Ship; typedef struct Bullet { float x, y, vx, vy; /* Fields like in ship. */ uint32_t ttl; /* Time to live, in ticks. */ } Bullet; typedef struct Asteroid { float x, y, vx, vy, rot, /* Fields like ship. */ rot_speed, /* Angular velocity (rot speed and sense). */ size; /* Asteroid size. */ uint8_t shape_seed; /* Seed to give random shape. */ } Asteroid; #define MAXBUL 10 /* Max bullets on the screen. */ #define MAXAST 32 /* Max asteroids on the screen. */ #define SHIP_HIT_ANIMATION_LEN 15 typedef struct AsteroidsApp { /* GUI */ Gui *gui; ViewPort *view_port; /* We just use a raw viewport and we render everything into the low level canvas. */ FuriMessageQueue *event_queue; /* Keypress events go here. */ /* Game state. */ int running; /* Once false exists the app. */ bool gameover; /* Gameover status. */ uint32_t ticks; /* Game ticks. Increments at each refresh. */ uint32_t score; /* Game score. */ uint32_t lives; /* Number of lives in the current game. */ uint32_t ship_hit; /* When non zero, the ship was hit by an asteroid and we need to show an animation as long as its value is non-zero (and decrease it's value at each tick of animation). */ /* Ship state. */ struct Ship ship; /* Bullets state. */ struct Bullet bullets[MAXBUL]; /* Each bullet state. */ int bullets_num; /* Active bullets. */ uint32_t last_bullet_tick; /* Tick the last bullet was fired. */ /* Asteroids state. */ Asteroid asteroids[MAXAST]; /* Each asteroid state. */ int asteroids_num; /* Active asteroids. */ uint32_t pressed[InputKeyMAX]; /* pressed[id] is true if pressed. Each array item contains the time in milliseconds the key was pressed. */ bool fire; /* Short press detected: fire a bullet. */ } AsteroidsApp; /* ============================== Prototyeps ================================ */ // Only functions called before their definition are here. void restart_game_after_gameover(AsteroidsApp *app); uint32_t key_pressed_time(AsteroidsApp *app, InputKey key); /* ============================ 2D drawing ================================== */ /* This structure represents a polygon of at most POLY_MAX points. * The function draw_poly() is able to render it on the screen, rotated * by the amount specified. */ #define POLY_MAX 8 typedef struct Poly { float x[POLY_MAX]; float y[POLY_MAX]; uint32_t points; /* Number of points actually populated. */ } Poly; /* Define the polygons we use. */ Poly ShipPoly = { {-3, 0, 3}, {-3, 6, -3}, 3 }; /* Rotate the point of the poligon 'poly' and store the new rotated * polygon in 'rot'. The polygon is rotated by an angle 'a', with * center at 0,0. */ void rotate_poly(Poly *rot, Poly *poly, float a) { /* We want to compute sin(a) and cos(a) only one time * for every point to rotate. It's a slow operation. */ float sin_a = (float)sin(a); float cos_a = (float)cos(a); for (uint32_t j = 0; j < poly->points; j++) { rot->x[j] = poly->x[j]*cos_a - poly->y[j]*sin_a; rot->y[j] = poly->y[j]*cos_a + poly->x[j]*sin_a; } rot->points = poly->points; } /* This is an 8 bit LFSR we use to generate a predictable and fast * pseudorandom sequence of numbers, to give a different shape to * each asteroid. */ void lfsr_next(unsigned char *prev) { unsigned char lsb = *prev & 1; *prev = *prev >> 1; if (lsb == 1) *prev ^= 0b11000111; *prev ^= *prev<<7; /* Mix things a bit more. */ } /* Render the polygon 'poly' at x,y, rotated by the specified angle. */ void draw_poly(Canvas *const canvas, Poly *poly, uint8_t x, uint8_t y, float a) { Poly rot; rotate_poly(&rot,poly,a); canvas_set_color(canvas, ColorBlack); for (uint32_t j = 0; j < rot.points; j++) { uint32_t a = j; uint32_t b = j+1; if (b == rot.points) b = 0; canvas_draw_line(canvas,x+rot.x[a],y+rot.y[a], x+rot.x[b],y+rot.y[b]); } } /* A bullet is just a + pixels pattern. A single pixel is not * visible enough. */ void draw_bullet(Canvas *const canvas, Bullet *b) { canvas_draw_dot(canvas,b->x-1,b->y); canvas_draw_dot(canvas,b->x+1,b->y); canvas_draw_dot(canvas,b->x,b->y); canvas_draw_dot(canvas,b->x,b->y-1); canvas_draw_dot(canvas,b->x,b->y+1); } /* Draw an asteroid. The asteroid shapes is computed on the fly and * is not stored in a permanent shape structure. In order to generate * the shape, we use an initial fixed shape that we resize according * to the asteroid size, perturbate according to the asteroid shape * seed, and finally draw it rotated of the right amount. */ void draw_asteroid(Canvas *const canvas, Asteroid *ast) { Poly ap; /* Start with what is kinda of a circle. Note that this could be * stored into a template and copied here, to avoid computing * sin() / cos(). But the Flipper can handle it without problems. */ uint8_t r = ast->shape_seed; for (int j = 0; j < 8; j++) { float a = (PI*2)/8*j; /* Before generating the point, to make the shape unique generate * a random factor between .7 and 1.3 to scale the distance from * the center. However this asteroid should have its unique shape * that remains always the same, so we use a predictable PRNG * implemented by an 8 bit shift register. */ lfsr_next(&r); float scaling = .7+((float)r/255*.6); ap.x[j] = (float)sin(a) * ast->size * scaling; ap.y[j] = (float)cos(a) * ast->size * scaling; } ap.points = 8; draw_poly(canvas,&ap,ast->x,ast->y,ast->rot); } /* Draw small ships in the top-right part of the screen, one for * each left live. */ void draw_left_lives(Canvas *const canvas, AsteroidsApp *app) { int lives = app->lives; int x = SCREEN_XRES-5; Poly mini_ship = { {-2, 0, 2}, {-2, 4, -2}, 3 }; while(lives--) { draw_poly(canvas,&mini_ship,x,6,PI); x -= 6; } } /* Given the current position, update it according to the velocity and * wrap it back to the other side if the object went over the screen. */ void update_pos_by_velocity(float *x, float *y, float vx, float vy) { /* Return back from one side to the other of the screen. */ *x += vx; *y += vy; if (*x >= SCREEN_XRES) *x = 0; else if (*x < 0) *x = SCREEN_XRES-1; if (*y >= SCREEN_YRES) *y = 0; else if (*y < 0) *y = SCREEN_YRES-1; } /* Render the current game screen. */ void render_callback(Canvas *const canvas, void *ctx) { AsteroidsApp *app = ctx; /* Clear screen. */ canvas_set_color(canvas, ColorWhite); canvas_draw_box(canvas, 0, 0, SCREEN_XRES-1, SCREEN_YRES-1); /* Draw score. */ canvas_set_color(canvas, ColorBlack); canvas_set_font(canvas, FontSecondary); char score[32]; snprintf(score,sizeof(score),"%lu",app->score); canvas_draw_str(canvas, 0, 8, score); /* Draw left ships. */ draw_left_lives(canvas,app); /* Draw ship, asteroids, bullets. */ draw_poly(canvas,&ShipPoly,app->ship.x,app->ship.y,app->ship.rot); for (int j = 0; j < app->bullets_num; j++) draw_bullet(canvas,&app->bullets[j]); for (int j = 0; j < app->asteroids_num; j++) draw_asteroid(canvas,&app->asteroids[j]); /* Game over text. */ if (app->gameover) { canvas_set_color(canvas, ColorBlack); canvas_set_font(canvas, FontPrimary); canvas_draw_str(canvas, 28, 35, "GAME OVER"); canvas_set_font(canvas, FontSecondary); canvas_draw_str(canvas, 25, 50, "Press OK to restart"); } } /* ============================ Game logic ================================== */ float distance(float x1, float y1, float x2, float y2) { float dx = x1-x2; float dy = y1-y2; return sqrt(dx*dx+dy*dy); } /* Detect a collision between the object at x1,y1 of radius r1 and * the object at x2, y2 of radius r2. A factor < 1 will make the * function detect the collision even if the objects are yet not * relly touching, while a factor > 1 will make it detect the collision * only after they are a bit overlapping. It basically is used to * rescale the distance. * * Note that in this simplified 2D world, objects are all considered * spheres (this is why this function only takes the radius). This * is, after all, kinda accurate for asteroids, for bullets, and * even for the ship "core" itself. */ bool objects_are_colliding(float x1, float y1, float r1, float x2, float y2, float r2, float factor) { /* The objects are colliding if the distance between object 1 and 2 * is smaller than the sum of the two radiuses r1 and r2. * So it would be like: sqrt((x1-x2)^2+(y1-y2)^2) < r1+r2. * However we can avoid computing the sqrt (which is slow) by * squaring the second term and removing the square root, making * the comparison like this: * * (x1-x2)^2+(y1-y2)^2 < (r1+r2)^2. */ float dx = (x1-x2)*factor; float dy = (y1-y2)*factor; float rsum = r1+r2; return dx*dx+dy*dy < rsum*rsum; } /* Create a new bullet headed in the same direction of the ship. */ void ship_fire_bullet(AsteroidsApp *app) { if (app->bullets_num == MAXBUL) return; Bullet *b = &app->bullets[app->bullets_num]; b->x = app->ship.x; b->y = app->ship.y; b->vx = -sin(app->ship.rot); b->vy = cos(app->ship.rot); /* Ship should fire from its head, not in the middle. */ b->x += b->vx*5; b->y += b->vy*5; /* Give the bullet some velocity (for now the vector is just * normalized to 1). */ b->vx *= 3; b->vy *= 3; /* It's more realistic if we add the velocity vector of the * ship, too. Otherwise if the ship is going fast the bullets * will be slower, which is not how the world works. */ b->vx += app->ship.vx; b->vy += app->ship.vy; b->ttl = 50; /* The bullet will disappear after N ticks. */ app->bullets_num++; } /* Remove the specified bullet by id (index in the array). */ void remove_bullet(AsteroidsApp *app, int bid) { /* Replace the top bullet with the empty space left * by the removal of this bullet. This way we always take the * array dense, which is an advantage when looping. */ int n = --app->bullets_num; if (n && bid != n) app->bullets[bid] = app->bullets[n]; } /* Create a new asteroid, away from the ship. Return the * pointer to the asteroid object, so that the caller can change * certain things of the asteroid if needed. */ Asteroid *add_asteroid(AsteroidsApp *app) { if (app->asteroids_num == MAXAST) return NULL; float size = 4+rand()%15; float min_distance = 20; float x,y; do { x = rand() % SCREEN_XRES; y = rand() % SCREEN_YRES; } while(distance(app->ship.x,app->ship.y,x,y) < min_distance+size); Asteroid *a = &app->asteroids[app->asteroids_num++]; a->x = x; a->y = y; a->vx = 2*(-.5 + ((float)rand()/RAND_MAX)); a->vy = 2*(-.5 + ((float)rand()/RAND_MAX)); a->size = size; a->rot = 0; a->rot_speed = ((float)rand()/RAND_MAX)/10; if (app->ticks & 1) a->rot_speed = -(a->rot_speed); a->shape_seed = rand() & 255; return a; } /* Remove the specified asteroid by id (index in the array). */ void remove_asteroid(AsteroidsApp *app, int id) { /* Replace the top asteroid with the empty space left * by the removal of this one. This way we always take the * array dense, which is an advantage when looping. */ int n = --app->asteroids_num; if (n && id != n) app->asteroids[id] = app->asteroids[n]; } /* Called when an asteroid was reached by a bullet. The asteroid * hit is the one with the specified 'id'. */ void asteroid_was_hit(AsteroidsApp *app, int id) { float sizelimit = 6; // Smaller than that polverize in one shot. Asteroid *a = &app->asteroids[id]; /* Asteroid is large enough to break into fragments. */ float size = a->size; float x = a->x, y = a->y; remove_asteroid(app,id); if (size > sizelimit) { int max_fragments = size / sizelimit; int fragments = 2+rand()%max_fragments; float newsize = size/fragments; if (newsize < 2) newsize = 2; for (int j = 0; j < fragments; j++) { a = add_asteroid(app); if (a == NULL) break; // Too many asteroids on screen. a->x = x + -(size/2) + rand() % (int)newsize; a->y = y + -(size/2) + rand() % (int)newsize; a->size = newsize; } } else { app->score++; } } /* Set gameover state. When in game-over mode, the game displays a gameover * text with a background of many asteroids floating around. */ void game_over(AsteroidsApp *app) { restart_game_after_gameover(app); app->gameover = true; int asteroids = 8; while(asteroids-- && add_asteroid(app) != NULL); } /* Function called when a collision between the asteroid and the * ship is detected. */ void ship_was_hit(AsteroidsApp *app) { app->ship_hit = SHIP_HIT_ANIMATION_LEN; if (app->lives) { app->lives--; } else { game_over(app); } } /* Restart game after the ship is hit. Will reset the ship position, bullets * and asteroids to restart the game. */ void restart_game(AsteroidsApp *app) { app->ship.x = SCREEN_XRES / 2; app->ship.y = SCREEN_YRES / 2; app->ship.rot = PI; /* Start headed towards top. */ app->ship.vx = 0; app->ship.vy = 0; app->bullets_num = 0; app->last_bullet_tick = 0; app->asteroids_num = 0; } /* Called after gameover to restart the game. This function * also calls restart_game(). */ void restart_game_after_gameover(AsteroidsApp *app) { app->gameover = false; app->ticks = 0; app->score = 0; app->ship_hit = 0; app->lives = GAME_START_LIVES; restart_game(app); } /* Move bullets. */ void update_bullets_position(AsteroidsApp *app) { for (int j = 0; j < app->bullets_num; j++) { update_pos_by_velocity(&app->bullets[j].x,&app->bullets[j].y, app->bullets[j].vx,app->bullets[j].vy); if (--app->bullets[j].ttl == 0) { remove_bullet(app,j); j--; /* Process this bullet index again: the removal will fill it with the top bullet to take the array dense. */ } } } /* Move asteroids. */ void update_asteroids_position(AsteroidsApp *app) { for (int j = 0; j < app->asteroids_num; j++) { update_pos_by_velocity(&app->asteroids[j].x,&app->asteroids[j].y, app->asteroids[j].vx,app->asteroids[j].vy); app->asteroids[j].rot += app->asteroids[j].rot_speed; if (app->asteroids[j].rot < 0) app->asteroids[j].rot = 2*PI; else if (app->asteroids[j].rot > 2*PI) app->asteroids[j].rot = 0; } } /* Collision detection and game state update based on collisions. */ void detect_collisions(AsteroidsApp *app) { /* Detect collision between bullet and asteroid. */ for (int j = 0; j < app->bullets_num; j++) { Bullet *b = &app->bullets[j]; for (int i = 0; i < app->asteroids_num; i++) { Asteroid *a = &app->asteroids[i]; if (objects_are_colliding(a->x, a->y, a->size, b->x, b->y, 1.5, 1)) { asteroid_was_hit(app,i); remove_bullet(app,j); /* The bullet no longer exist. Break the loop. * However we want to start processing from the * same bullet index, since now it is used by * another bullet (see remove_bullet()). */ j--; /* Scan this j value again. */ break; } } } /* Detect collision between ship and asteroid. */ for (int j = 0; j < app->asteroids_num; j++) { Asteroid *a = &app->asteroids[j]; if (objects_are_colliding(a->x, a->y, a->size, app->ship.x, app->ship.y, 4, 1)) { ship_was_hit(app); break; } } } /* This is the main game execution function, called 10 times for * second (with the Flipper screen latency, an higher FPS does not * make sense). In this function we update the position of objects based * on velocity. Detect collisions. Update the score and so forth. * * Each time this function is called, app->tick is incremented. */ void game_tick(void *ctx) { AsteroidsApp *app = ctx; /* There are two special screens: * * 1. Ship was hit, we frozen the game as long as ship_hit isn't zero * again, and show an animation of a rotating ship. */ if (app->ship_hit) { app->ship.rot += 0.5; app->ship_hit--; view_port_update(app->view_port); if (app->ship_hit == 0) { restart_game(app); } return; } else if (app->gameover) { /* 2. Game over. We need to update only background asteroids. In this * state the game just displays a GAME OVER text with the floating * asteroids in backgroud. */ if (key_pressed_time(app,InputKeyOk) > 100) { restart_game_after_gameover(app); } update_asteroids_position(app); view_port_update(app->view_port); return; } /* Handle keypresses. */ if (app->pressed[InputKeyLeft]) app->ship.rot -= .35; if (app->pressed[InputKeyRight]) app->ship.rot += .35; if (key_pressed_time(app,InputKeyOk) > 70) { app->ship.vx -= 0.5*(float)sin(app->ship.rot); app->ship.vy += 0.5*(float)cos(app->ship.rot); } else if (app->pressed[InputKeyDown]) { app->ship.vx *= 0.75; app->ship.vy *= 0.75; } /* Fire a bullet if needed. app->fire is set in * asteroids_update_keypress_state() since depends on exact * pressure timing. */ if (app->fire) { uint32_t bullet_min_period = 200; // In milliseconds uint32_t now = furi_get_tick(); if (now - app->last_bullet_tick >= bullet_min_period) { ship_fire_bullet(app); app->last_bullet_tick = now; } app->fire = false; } /* Update positions and detect collisions. */ update_pos_by_velocity(&app->ship.x,&app->ship.y,app->ship.vx,app->ship.vy); update_bullets_position(app); update_asteroids_position(app); detect_collisions(app); /* From time to time, create a new asteroid. The more asteroids * already on the screen, the smaller probability of creating * a new one. */ if (app->asteroids_num == 0 || (random() % 5000) < (30/(1+app->asteroids_num))) { add_asteroid(app); } app->ticks++; view_port_update(app->view_port); } /* ======================== Flipper specific code =========================== */ /* Here all we do is putting the events into the queue that will be handled * in the while() loop of the app entry point function. */ void input_callback(InputEvent* input_event, void* ctx) { AsteroidsApp *app = ctx; furi_message_queue_put(app->event_queue,input_event,FuriWaitForever); } /* Allocate the application state and initialize a number of stuff. * This is called in the entry point to create the application state. */ AsteroidsApp* asteroids_app_alloc() { AsteroidsApp *app = malloc(sizeof(AsteroidsApp)); app->gui = furi_record_open(RECORD_GUI); app->view_port = view_port_alloc(); view_port_draw_callback_set(app->view_port, render_callback, app); view_port_input_callback_set(app->view_port, input_callback, app); gui_add_view_port(app->gui, app->view_port, GuiLayerFullscreen); app->event_queue = furi_message_queue_alloc(8, sizeof(InputEvent)); app->running = 1; /* Turns 0 when back is pressed. */ restart_game_after_gameover(app); memset(app->pressed,0,sizeof(app->pressed)); return app; } /* Free what the application allocated. It is not clear to me if the * Flipper OS, once the application exits, will be able to reclaim space * even if we forget to free something here. */ void asteroids_app_free(AsteroidsApp *app) { furi_assert(app); // View related. view_port_enabled_set(app->view_port, false); gui_remove_view_port(app->gui, app->view_port); view_port_free(app->view_port); furi_record_close(RECORD_GUI); furi_message_queue_free(app->event_queue); app->gui = NULL; free(app); } /* Return the time in milliseconds the specified key is continuously * pressed. Or 0 if it is not pressed. */ uint32_t key_pressed_time(AsteroidsApp *app, InputKey key) { return app->pressed[key] == 0 ? 0 : furi_get_tick() - app->pressed[key]; } /* Handle keys interaction. */ void asteroids_update_keypress_state(AsteroidsApp *app, InputEvent input) { if (input.type == InputTypePress) { app->pressed[input.key] = furi_get_tick(); } else if (input.type == InputTypeRelease) { uint32_t dur = key_pressed_time(app,input.key); app->pressed[input.key] = 0; if (dur < 200 && input.key == InputKeyOk) app->fire = true; } } int32_t asteroids_app_entry(void* p) { UNUSED(p); AsteroidsApp *app = asteroids_app_alloc(); /* Create a timer. We do data analysis in the callback. */ FuriTimer *timer = furi_timer_alloc(game_tick, FuriTimerTypePeriodic, app); furi_timer_start(timer, furi_kernel_get_tick_frequency() / 10); /* This is the main event loop: here we get the events that are pushed * in the queue by input_callback(), and process them one after the * other. */ InputEvent input; while(app->running) { FuriStatus qstat = furi_message_queue_get(app->event_queue, &input, 100); if (qstat == FuriStatusOk) { if (DEBUG_MSG) FURI_LOG_E(TAG, "Main Loop - Input: type %d key %u", input.type, input.key); /* Handle navigation here. Then handle view-specific inputs * in the view specific handling function. */ if (input.type == InputTypeShort && input.key == InputKeyBack) { app->running = 0; } else { asteroids_update_keypress_state(app,input); } } else { /* Useful to understand if the app is still alive when it * does not respond because of bugs. */ if (DEBUG_MSG) { static int c = 0; c++; if (!(c % 20)) FURI_LOG_E(TAG, "Loop timeout"); } } } furi_timer_free(timer); asteroids_app_free(app); return 0; }