include/dangerzone/render/anim.h

@@ -1,22 +1,55 @@
-#pragma once
+#ifndef DANGERZONE_RENDER_ANIM_H
+#define DANGERZONE_RENDER_ANIM_H
 
-#include <dangerzone/engine.h>
+#include <stdbool.h>
+#include <stddef.h>
 #include <stdint.h>
 
-/**
- * animate a rectangle's position changing over time
- * => x0 -> x1, y0 -> y1, all else stays the same
- *
- * ONLY DOES ONE FRAME OF THE ANIMATION
+#define ANIM_MAX_TRACKS 64
+
+typedef struct {
+    float x;
+    float y;
+    float w;
+    float h;
+} anim_rect_t;
+
+/* payload is application data; the animation module does not interpret it. */
+typedef struct {
+    uint32_t payload;
+    anim_rect_t from;
+    anim_rect_t to;
+} anim_track_t;
+
+typedef struct {
+    uint32_t payload;
+    anim_rect_t rect;
+} anim_item_t;
+
+typedef struct {
+    anim_track_t tracks[ANIM_MAX_TRACKS];
+    anim_item_t items[ANIM_MAX_TRACKS];
+    size_t count;
+    float elapsed;
+    float duration;
+    bool active;
+} anim_t;
+
+void anim_init(anim_t *anim);
+
+/*
+ * Start tracks from their initial rectangles to their destination rectangles.
+ * Returns false for invalid input or if count exceeds ANIM_MAX_TRACKS.
+ * A zero-duration animation completes immediately.
  */
-void
-anim_rect_pos(
-    framebuffer_e framebuffer,
-    uint32_t x0,
-    uint32_t y0,
-    uint32_t x1,
-    uint32_t y1,
-    uint32_t w,
-    uint32_t h,
-    uint32_t color
-);
+bool anim_start(anim_t *anim, const anim_track_t *tracks,
+                size_t count, float duration);
+
+/* Advance by nonnegative seconds. Returns true once the animation is finished. */
+bool anim_update(anim_t *anim, float dt);
+
+bool anim_is_active(const anim_t *anim);
+size_t anim_count(const anim_t *anim);
+const anim_item_t *anim_items(const anim_t *anim);
+
+#endif

src/engine/render/anim.c

@@ -1,38 +1,89 @@
 #include <dangerzone/render/anim.h>
 
+#include <string.h>
+
 void
-anim_rect_pos(
-    framebuffer_e framebuffer,
-    uint32_t x0,
-    uint32_t y0,
-    uint32_t x1,
-    uint32_t y1,
-    uint32_t w,
-    uint32_t h,
-    uint32_t color
-) {
-    // there's nowhere to move
-    if (x0 == x1 && y0 == y1) {
-        return;
+anim_init(anim_t *anim)
+{
+    if (anim != NULL)
+        memset(anim, 0, sizeof *anim);
+}
+
+bool
+anim_start(anim_t *anim, const anim_track_t *tracks,
+           size_t count, float duration)
+{
+    if (anim == NULL || (count != 0 && tracks == NULL) ||
+        count > ANIM_MAX_TRACKS || duration < 0.0f) {
+        return false;
     }
 
-    uint32_t dirx = (x1 - x0 > 0) ? 1 : -1;
-    uint32_t diry = (y1 - y0 > 0) ? 1 : -1;
+    anim->count = count;
+    anim->elapsed = 0.0f;
+    anim->duration = duration;
+    anim->active = duration > 0.0f && count > 0;
 
-    if (x0 == x1) {
-        dirx = 0;
+    for (size_t i = 0; i < count; ++i) {
+        anim->tracks[i] = tracks[i];
+        anim->items[i].payload = tracks[i].payload;
+        anim->items[i].rect = tracks[i].from;
     }
 
-    if (y0 == y1) {
-        diry = 0;
+    if (!anim->active) {
+        for (size_t i = 0; i < count; ++i)
+            anim->items[i].rect = tracks[i].to;
     }
+
+    return true;
+}
+
+bool
+anim_update(anim_t *anim, float dt)
+{
+    if (anim == NULL || !anim->active)
+        return true;
 
-    /**
-     * 1. shift the rectangle by one pixel in the direction of movement
-     * 2. remove the trailing row / column left  
-     */
+    if (dt < 0.0f)
+        dt = 0.0f;
 
-    if (true) {
+    anim->elapsed += dt;
 
+    float t = anim->elapsed / anim->duration;
+    if (t >= 1.0f) {
+        t = 1.0f;
+        anim->active = false;
     }
+
+    /* Ease-out. Replace with t for linear motion. */
+    float eased = 1.0f - (1.0f - t) * (1.0f - t);
+
+    for (size_t i = 0; i < anim->count; ++i) {
+        const anim_track_t *track = &anim->tracks[i];
+        anim_rect_t *rect = &anim->items[i].rect;
+
+        rect->x = track->from.x + (track->to.x - track->from.x) * eased;
+        rect->y = track->from.y + (track->to.y - track->from.y) * eased;
+        rect->w = track->from.w + (track->to.w - track->from.w) * eased;
+        rect->h = track->from.h + (track->to.h - track->from.h) * eased;
+    }
+
+    return !anim->active;
+}
+
+bool
+anim_is_active(const anim_t *anim)
+{
+    return anim != NULL && anim->active;
+}
+
+size_t
+anim_count(const anim_t *anim)
+{
+    return anim != NULL ? anim->count : 0;
+}
+
+const anim_item_t *
+anim_items(const anim_t *anim)
+{
+    return anim != NULL ? anim->items : NULL;
 }

src/examples/2048.c

@@ -1,8 +1,10 @@
 #include <dangerzone/engine.h>
+#include <dangerzone/render/anim.h>
 #include <dangerzone/render/misc.h>
 #include <dangerzone/render/rect.h>
 #include <dangerzone/render/text.h>
 
+#include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -10,6 +12,8 @@
 #include <time.h>
 
 #define SIZE 4
+#define MOVE_DURATION 0.12f
+#define BORDER_WIDTH 10
 
 typedef enum {
     LEFT,
@@ -18,492 +22,381 @@ typedef enum {
     DOWN
 } dir_e;
 
-typedef struct {
-    uint32_t x;
-    uint32_t y;
-} v2_t;
-
 typedef struct {
     uint32_t value;
-    v2_t pos;
-} tile_t;
+    int row;
+    int col;
+} line_tile_t;
 
 typedef struct {
-    tile_t area[SIZE][SIZE];
+    uint32_t area[SIZE][SIZE];
     dir_e direction;
     uint32_t score;
 } game_t;
 
 static game_t game;
 
-#define MOVE_DURATION 0.12f
+static anim_t movement;
+static anim_track_t move_tracks[SIZE * SIZE];
+static size_t move_track_count;
 
-typedef struct {
-    uint32_t value;
-    int from_row, from_col;
-    int to_row, to_col;
-    bool merge_target;
-} tile_anim_t;
+static double last_frame_time;
 
-static tile_anim_t anims[SIZE * SIZE];
-static size_t anim_count;
-static float anim_elapsed;
-static bool anim_active;
-uint32_t before[SIZE][SIZE];
-
-void
-print_area()
+/* Pixel size is calculated from the current window size while drawing. */
+static uint32_t
+colors(uint32_t number)
 {
-    printf("AREA:\n");
-    for (int i = 0; i < SIZE; i++) {
-        printf("[");
-        for (int j = 0; j < SIZE - 1; j++) {
-            printf("%d, ", game.area[i][j].value);
+    switch (number) {
+    case 0:  return 0xFFFFFF;
+    case 2:  return 0x00FF00;
+    case 4:  return 0xFF0000;
+    case 8:  return 0x0000FF;
+    default: return 0xFFFFFF;
     }
-        printf("%d]\n", game.area[i][SIZE - 1].value);
-    }
-    printf("\n");
 }
 
-bool
-move()
+/*
+ * Return the board coordinate for position p in a line, where p=0 is
+ * the side toward which tiles move.
+ */
+static void
+line_coordinate(dir_e direction, int line, int p, int *row, int *col)
 {
-    bool retval = false;
-    tile_t *current, *next;
-    int k_start, k_end, k_step;
-    switch (game.direction) {
+    switch (direction) {
     case LEFT:
-    case UP:
-        k_start = 0;
-        k_end = SIZE - 1;
-        k_step = 1;
+        *row = line;
+        *col = p;
         break;
     case RIGHT:
-    case DOWN:
-        k_start = SIZE - 1;
-        k_end = 0;
-        k_step = -1;
-        break;
-    default:
-        break;
-    }
-
-    for (int i = 0; i < SIZE; i++) {
-        for (int j = 0; j < SIZE; j++) {
-            for (int k = k_start; (k_start <= k_end) ? k < k_end : k > k_end; k += k_step) {
-                switch (game.direction) {
-                case LEFT:
-                case RIGHT:
-                    current = &game.area[i][k];
-                    next = &game.area[i][k + k_step];
+        *row = line;
+        *col = SIZE - 1 - p;
         break;
     case UP:
+        *row = p;
+        *col = line;
+        break;
     case DOWN:
-                    current = &game.area[k][i];
-                    next = &game.area[k + k_step][i];
+        *row = SIZE - 1 - p;
+        *col = line;
         break;
     }
+}
 
-                if (current->value == 0 && next->value != 0) {
-                    current->pos = (v2_t) {
-                        .x = next->pos.x,
-                        .y = next->pos.y
+/*
+ * Convert a board cell into the pixel rectangle used to draw its tile.
+ * Keep this consistent with draw_tile_rect() and the cell backgrounds.
+ */
+static anim_rect_t
+tile_rect(int row, int col, uint32_t tile_size)
+{
+    float side = (float)(tile_size - BORDER_WIDTH);
+
+    return (anim_rect_t) {
+        .x = BORDER_WIDTH / 2.0f + col * (float)tile_size,
+        .y = BORDER_WIDTH / 2.0f + row * (float)tile_size,
+        .w = side,
+        .h = side
     };
-                    current->value = next->value;
-                    next->value = 0;
-                    retval = true;
-                }
-            }
-        }
-    }
-
-    return retval;
 }
 
+static void
+add_move_track(uint32_t value,
+               int from_row, int from_col,
+               int to_row, int to_col)
+{
+    if (move_track_count >= SIZE * SIZE)
+        return;
 
+    uint32_t tile_size = game_state->width / SIZE;
+
+    move_tracks[move_track_count++] = (anim_track_t) {
+        .payload = value,
+        .from = tile_rect(from_row, from_col, tile_size),
+        .to = tile_rect(to_row, to_col, tile_size)
+    };
+}
+
+/*
+ * Process one row or column in movement order. Update the board and record
+ * pixel-space animation tracks for every original tile.
+ */
 static bool
-merge_line(
-    uint32_t line[SIZE]
-) {
-    uint32_t out[SIZE] = {0};
-    int write = 0;
-    bool previous_was_merged = false;
+process_line(dir_e direction, int line, uint32_t output[SIZE])
+{
+    line_tile_t input[SIZE];
+    int input_count = 0;
+    int output_count = 0;
 
-    for (int read = 0; read < SIZE; ++read) {
-        uint32_t value = line[read];
+    for (int p = 0; p < SIZE; ++p) {
+        int row, col;
+        line_coordinate(direction, line, p, &row, &col);
 
-        if (value == 0)
-            continue;
+        uint32_t value = game.area[row][col];
+        if (value != 0) {
+            input[input_count++] = (line_tile_t) {
+                .value = value,
+                .row = row,
+                .col = col
+            };
+        }
+    }
 
-        if (write > 0 &&
-            out[write - 1] == value &&
-            !previous_was_merged) {
-            out[write - 1] *= 2;
-            game.score += out[write - 1];
-            previous_was_merged = true;
+    memset(output, 0, sizeof(uint32_t) * SIZE);
+
+    for (int i = 0; i < input_count; ) {
+        int dest_row, dest_col;
+        line_coordinate(direction, line, output_count,
+                        &dest_row, &dest_col);
+
+        if (i + 1 < input_count &&
+            input[i].value == input[i + 1].value) {
+            uint32_t merged_value = input[i].value * 2;
+
+            output[output_count] = merged_value;
+            game.score += merged_value;
+
+            /* Both source tiles travel to the same merge destination. */
+            add_move_track(input[i].value,
+                           input[i].row, input[i].col,
+                           dest_row, dest_col);
+            add_move_track(input[i + 1].value,
+                           input[i + 1].row, input[i + 1].col,
+                           dest_row, dest_col);
+
+            i += 2;
         } else {
-            out[write++] = value;
-            previous_was_merged = false;
+            output[output_count] = input[i].value;
+
+            add_move_track(input[i].value,
+                           input[i].row, input[i].col,
+                           dest_row, dest_col);
+
+            ++i;
         }
+
+        ++output_count;
+    }
+
+    bool changed = false;
+    for (int p = 0; p < SIZE; ++p) {
+        int row, col;
+        line_coordinate(direction, line, p, &row, &col);
+
+        if (game.area[row][col] != output[p])
+            changed = true;
+
+        game.area[row][col] = output[p];
     }
 
-    bool changed = memcmp(line, out, sizeof out) != 0;
-    memcpy(line, out, sizeof out);
     return changed;
 }
 
-bool
-combine(
-    bool has_moved
-) {
+static bool
+slide(dir_e direction)
+{
+    if (anim_is_active(&movement))
+        return false;
+
+    game.direction = direction;
+    move_track_count = 0;
+
     bool changed = false;
-    uint32_t line[SIZE];
 
-    for (int n = 0; n < SIZE; ++n) {
-        for (int p = 0; p < SIZE; ++p) {
-            int r, c;
-
-            switch (game.direction) {
-            case LEFT:  r = n; c = p;             break;
-            case RIGHT: r = n; c = SIZE - 1 - p;  break;
-            case UP:    r = p; c = n;             break;
-            case DOWN:  r = SIZE - 1 - p; c = n;  break;
-            default: return has_moved;
+    for (int line = 0; line < SIZE; ++line) {
+        uint32_t output[SIZE];
+        if (process_line(direction, line, output))
+            changed = true;
     }
 
-            line[p] = game.area[r][c].value;
+    if (!changed) {
+        move_track_count = 0;
+        return false;
     }
 
-        changed |= merge_line(line);
-
-        for (int p = 0; p < SIZE; ++p) {
-            int r, c;
-
-            switch (game.direction) {
-            case LEFT:  r = n; c = p;             break;
-            case RIGHT: r = n; c = SIZE - 1 - p;  break;
-            case UP:    r = p; c = n;             break;
-            case DOWN:  r = SIZE - 1 - p; c = n;  break;
-            default: return has_moved;
-            }
-
-            game.area[r][c].value = line[p];
-        }
-    }
-
-    return has_moved || changed;
+    return anim_start(&movement, move_tracks, move_track_count,
+                      MOVE_DURATION);
 }
 
-// finds a random empty position and puts a two there
-void
-new_2()
+static void
+new_2(void)
 {
-    // collect all zeroes
-    v2_t zeroes[SIZE * SIZE] = {0};
-    uint32_t zero_count = 0;
-    for (int i = 0; i < SIZE; i++) {
-        for (int j = 0; j < SIZE; j++) {
-            if (game.area[i][j].value == 0) {
-                zeroes[zero_count++] = (v2_t){.x=j,.y=i};
+    int empty_rows[SIZE * SIZE];
+    int empty_cols[SIZE * SIZE];
+    int count = 0;
+
+    for (int r = 0; r < SIZE; ++r) {
+        for (int c = 0; c < SIZE; ++c) {
+            if (game.area[r][c] == 0) {
+                empty_rows[count] = r;
+                empty_cols[count] = c;
+                ++count;
             }
         }
     }
 
-    // choose among them
-    uint32_t rand_index = rand() % zero_count;
-    game.area[zeroes[rand_index].y][zeroes[rand_index].x].value = 2;
+    if (count == 0)
+        return;
+
+    int pick = rand() % count;
+    game.area[empty_rows[pick]][empty_cols[pick]] = 2;
 }
 
+/* Polling events every frame. */
 void
-slide()
-{
-    // 1. move all squares in one direction
-    bool has_moved = move();
-
-    // 2. then combine them and shift the potential rest by one in the given direction
-    bool has_combined = combine(has_moved);
-    
-    // 3. generate a new 2
-    if (has_moved || has_combined) {
-        new_2();
-    }
-}
-
-// polling events every frame
-void
-client_poll_event()
+client_poll_event(void)
 {
     SDL_Event ev = game_state->event;
 
     if (ev.type == SDL_EVENT_QUIT) {
         game_state->is_running = false;
+        return;
     }
 
-	if (ev.type == SDL_EVENT_KEY_DOWN) {
+    if (ev.type != SDL_EVENT_KEY_DOWN)
+        return;
+
     switch (ev.key.key) {
     case SDLK_Q:
         game_state->is_running = false;
         break;
     case SDLK_W:
-            game.direction = UP;
-            for (int r = 0; r < SIZE; ++r)
-                for (int c = 0; c < SIZE; ++c)
-                    before[r][c] = game.area[r][c].value;
-            slide();
+        slide(UP);
         break;
     case SDLK_S:
-            game.direction = DOWN;
-            for (int r = 0; r < SIZE; ++r)
-                for (int c = 0; c < SIZE; ++c)
-                    before[r][c] = game.area[r][c].value;
-            slide();
+        slide(DOWN);
         break;
     case SDLK_A:
-            game.direction = LEFT;
-            for (int r = 0; r < SIZE; ++r)
-                for (int c = 0; c < SIZE; ++c)
-                    before[r][c] = game.area[r][c].value;
-            slide();
+        slide(LEFT);
         break;
     case SDLK_D:
-            game.direction = RIGHT;
-            for (int r = 0; r < SIZE; ++r)
-                for (int c = 0; c < SIZE; ++c)
-                    before[r][c] = game.area[r][c].value;
-            slide();
+        slide(RIGHT);
         break;
     default:
         break;
     }
-	}
 }
 
-#define CHR(ord) ((ord) + 48)
-#define ORD(chr) ((chr) - 48)
-
-uint32_t
-colors(
-    uint32_t number
-) {
-    switch (number) {
-    case 0:
-        return 0xFFFFFF;
-    case 2:
-        return 0x00FF00;
-    case 4:
-        return 0xFF0000;
-    case 8:
-        return 0x0000FF;
-    default:
-        return 0xFFFFFF;
-    }
-}
-
-uint32_t
-numlen(
-    uint32_t n
-) {
-    uint32_t len = 0;
-
-    while (n > 0) {
-        len++;
-        n /= 10;
-    }
-
-    return len;
-}
-
-uint32_t
-power(
-    uint32_t x,
-    uint32_t n
-) {
-    // x ^ n
-    uint32_t acc = 1;
-    for (int i = 0; i < n; i++) {
-        acc *= x;
-    }
-
-    return acc;
-}
-
-uint32_t
-numrev(
-    uint32_t n
-) {
-    uint32_t len = numlen(n);
-    uint32_t new = 0;
-    int i = 0;
-
-    while (n > 0) {
-        new += (n % 10) * power(10, len - (++i));
-        n /= 10;
-    }
-
-    return new;
-}
-
-v2_t last_area_positions[SIZE][SIZE] = {0};
-
-// performed every frame
-void
-client_update_framebuffer()
+static double
+monotonic_seconds(void)
 {
-	// clear_framebuffer(0xFFFF00);
-	// put_string("Welcome to the most\n*DANGEROUS* 2048 game!",
-	// 	20, 20, 2, 2, 3, 0x000000, 0xFFFF00
-	// );
+    struct timespec ts;
+    timespec_get(&ts, TIME_UTC);
+    return (double)ts.tv_sec + (double)ts.tv_nsec / 1e9;
+}
 
-    // FIXME: why?
-    //clear_framebuffer(BASE, 0x000000);
+static void
+draw_tile_rect(uint32_t value, float x, float y, float w, float h)
+{
+    uint32_t ix = (uint32_t)x;
+    uint32_t iy = (uint32_t)y;
+    uint32_t iw = (uint32_t)w;
+    uint32_t ih = (uint32_t)h;
+    uint32_t color = colors(value);
+
+    put_rect(OVERDRAW, ix, iy, iw, ih, color);
+
+    if (value != 0) {
+        char text[16];
+        snprintf(text, sizeof text, "%u", value);
+        put_string(OVERDRAW, text,
+                   ix + BORDER_WIDTH, iy + BORDER_WIDTH,
+                   3, 1, 12, 0x000000, color);
+    }
+}
+
+static void
+draw_tile(uint32_t value, int row, int col, uint32_t tile_size)
+{
+    anim_rect_t rect = tile_rect(row, col, tile_size);
+    draw_tile_rect(value, rect.x, rect.y, rect.w, rect.h);
+}
+
+void
+client_update_framebuffer(void)
+{
+    double now = monotonic_seconds();
+    float dt = last_frame_time == 0.0
+        ? 0.0f
+        : (float)(now - last_frame_time);
+    last_frame_time = now;
+
+    if (dt > 0.05f)
+        dt = 0.05f;
+
+    if (anim_is_active(&movement) && anim_update(&movement, dt)) {
+        new_2();
+    }
 
     uint32_t tile_size = game_state->width / SIZE;
-    uint8_t border_width = 10;
-    char *n_str;
-    bool alloced = false;
-    for (int i = 0; i < SIZE; i++) {
-        for (int j = 0; j < SIZE; j++) {
-            alloced = true;
-            // background
-            uint32_t x = (border_width / 2) + i * tile_size;
-            uint32_t y = (border_width / 2) + j * tile_size;
-            uint32_t w = tile_size - border_width;
-            uint32_t h = tile_size - border_width;
-            uint32_t background_color = colors(game.area[j][i].value);
+    uint32_t border_width = BORDER_WIDTH;
 
-            put_rect(BASE, x, y, w, h, 0xFFFFFF);
-            put_rect(OVERDRAW, x, y, w, h, background_color);
+    clear_framebuffer(OVERDRAW, 0x000000);
 
-            // number in foreground
-            uint32_t foreground_color = 0x000000;
-            uint8_t font_size = 3;
+    /* Draw all cell backgrounds first. */
+    for (int r = 0; r < SIZE; ++r) {
+        for (int c = 0; c < SIZE; ++c) {
+            uint32_t x = border_width / 2 + (uint32_t)c * tile_size;
+            uint32_t y = border_width / 2 + (uint32_t)r * tile_size;
+            uint32_t side = tile_size - border_width;
 
-            uint32_t n = game.area[j][i].value;
-            uint32_t n_len = numlen(n);
-            n_str = calloc(n_len + 1, sizeof(char));
-            if (n_str == NULL) {
-                game_state->is_running = false;
+            put_rect(BASE, x, y, side, side, 0xFFFFFF);
+            put_rect(OVERDRAW, x, y, side, side, 0xFFFFFF);
         }
-            sprintf(n_str, "%d", n);
-            uint32_t n_rev = numrev(n);
-            uint32_t digit_offset = 1;
-            if (n != 0) {
-                put_string(OVERDRAW, n_str, x + border_width, y + border_width, font_size, digit_offset, 12, foreground_color, background_color);
+    }
+
+    if (anim_is_active(&movement)) {
+        const anim_item_t *items = anim_items(&movement);
+        size_t count = anim_count(&movement);
+
+        for (size_t i = 0; i < count; ++i) {
+            draw_tile_rect(items[i].payload,
+                           items[i].rect.x, items[i].rect.y,
+                           items[i].rect.w, items[i].rect.h);
+        }
+    } else {
+        for (int r = 0; r < SIZE; ++r) {
+            for (int c = 0; c < SIZE; ++c) {
+                draw_tile(game.area[r][c], r, c, tile_size);
             }
         }
     }
 
-    // score display line (single line)
-    char *score_text = calloc(7 + 6 + 1, sizeof(char));
-    if (score_text == NULL) {
-        game_state->is_running = false;
-    }
-    alloced = true;
-
-    sprintf(score_text, "score: %6d", game.score);
-    put_string(OVERDRAW, score_text, border_width / 2, tile_size * SIZE + border_width / 2, 6, 1, 12, 0xFFFFFF, 0x000000);
-
-    if (alloced) {
-        free(n_str);
-        free(score_text);
-    }
+    char score_text[32];
+    snprintf(score_text, sizeof score_text, "score: %u", game.score);
+    put_string(OVERDRAW, score_text,
+               border_width / 2, tile_size * SIZE + border_width / 2,
+               6, 1, 12, 0xFFFFFF, 0x000000);
 }
 
-bool
-v2_eq(v2_t a, v2_t b)
+static void
+game_init(void)
 {
-    return a.x == b.x && a.y == b.y;
-}
+    memset(&game, 0, sizeof game);
+    anim_init(&movement);
+    srand((unsigned)time(NULL));
 
-bool
-v2_contains(v2_t v[], size_t size, v2_t elem)
-{
-    for (int i = 0; i < size; i++) {
-        if (v2_eq(v[i], elem)) {
-            return true;
-        }
-    }
-
-    return false;
-}
-
-void
-game_init(
-    uint32_t window_width
-) {
-    srand(time(NULL));
-
-    // generate MAX_NUMBER_OF_4 + MAX_NUMBER_OF_2 random indices in range 0..15 (row in 0..3, col in 0..3)
-    // this means that there will be at least MAX_NUMBER_OF_2 of 2s and MAX_NUMBER_OF_4 <= MAX_NUMBER_OF_2 4s
-    // => usually less 4s than 2s because the indices can get replaced
-#define MAX_NUMBER_OF_4 1
-#define MAX_NUMBER_OF_2 2
-
-    uint8_t row, col;
-    v2_t elem;
-    v2_t fours[MAX_NUMBER_OF_4], twos[MAX_NUMBER_OF_2];
-
-    int i = 0;
-    while (i < MAX_NUMBER_OF_4) {
-        row = rand() % SIZE;
-        col = rand() % SIZE;
-        elem = (v2_t){ .x = col, .y = row };
-        if (!v2_contains(twos, MAX_NUMBER_OF_4, elem)) {
-            fours[i++] = elem;
-        }
-    }
-    
-    i = 0;
-    while (i < MAX_NUMBER_OF_2) {
-        row = rand() % SIZE;
-        col = rand() % SIZE;
-        elem = (v2_t){ .x = col, .y = row };
-        if (!v2_contains(twos, MAX_NUMBER_OF_2, elem)) {
-            twos[i++] = elem;
-        }
-    }
-
-    for (int row = 0; row < SIZE; row++) {
-        for (int col = 0; col < SIZE; col++) {
-            game.area[row][col].pos = (v2_t){ 
-                .x = col * (window_width / SIZE), 
-                .y = row * (window_width / SIZE)
-            };
-            game.area[row][col].value = 0;
-        }
-    }
-
-    for (i = 0; i < MAX_NUMBER_OF_4; i++) {
-        game.area[fours[i].y][fours[i].x].value = 4;
-    }
-
-    for (i = 0; i < MAX_NUMBER_OF_2; i++) {
-        game.area[twos[i].y][twos[i].x].value = 2;
-    }
-    
-    game.direction = RIGHT;
-    game.score = 0;
+    /* Start with two 2-tiles. */
+    new_2();
+    new_2();
 }
 
 int
-main()
+main(void)
 {
     uint32_t window_width = 500;
-    uint32_t window_height = window_width * 1.12f;
+    uint32_t window_height = (uint32_t)(window_width * 1.12f);
 
-    game_init(window_width);
+    game_init();
 
-	// initialize the engine
-	if (engine_init(
-		window_width, window_height,
+    if (engine_init(window_width, window_height,
                     "Dangerous 2048",
                     client_poll_event,
-		client_update_framebuffer
-	)) {
+                    client_update_framebuffer)) {
         engine_start();
         engine_stop();
         return 0;
-	} else {
-		return 1;
     }
+
+    return 1;
 }
+