add better colors for 2048

Reviewed-on: #29

.gitignore

@@ -3,3 +3,4 @@
 build/
 src/engine/CMakeFiles
 examples/CMakeFiles
+*.xopp

include/dangerzone/engine.h

@@ -4,13 +4,22 @@
 #include <stdbool.h>
 #include <stdint.h>
 
+typedef enum {
+    BASE,
+    OVERDRAW
+} framebuffer_e;
+
 typedef struct {
 	SDL_Event event;
 	bool is_running;
-	bool framebuffer_dirty;
+	bool framebuffer_base_dirty;
+	bool framebuffer_overdraw_dirty;
 	SDL_Rect dirty_rect;
 	uint16_t width, height;
-	uint32_t *framebuffer;
+    // base layer ~ layer 0
+	uint32_t *framebuffer_base; 
+    // layer on top of that ~ layer 1
+    uint32_t *framebuffer_overdraw; 
 } game_state_t;
 
 extern game_state_t *game_state;

include/dangerzone/render/anim.h

@@ -0,0 +1,55 @@
+#ifndef DANGERZONE_RENDER_ANIM_H
+#define DANGERZONE_RENDER_ANIM_H
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#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.
+ */
+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

include/dangerzone/render/misc.h

@@ -1,9 +1,12 @@
 #pragma once
 
+#include <dangerzone/engine.h>
+
 #include <stdint.h>
 
 void 
 put_pixel(
+    framebuffer_e framebuffer,
 	unsigned int x, 
 	unsigned int y, 
 	uint32_t color
@@ -11,5 +14,6 @@ put_pixel(
 
 void 
 clear_framebuffer(
+    framebuffer_e framebuffer,
 	uint32_t color
 );

include/dangerzone/render/rect.h

@@ -1,9 +1,12 @@
 #pragma once
 
+#include <dangerzone/engine.h>
+
 #include <stdint.h>
 
 void
 put_rect(
+    framebuffer_e framebuffer,
 	uint32_t x, 
 	uint32_t y, 
 	uint32_t w, 
@@ -11,6 +14,7 @@ put_rect(
 	uint32_t color
 );
 
+// TODO: remove, deprecated, you can use put_rect for the same thing
 void
 clear_rect(int x, int y, int w, int h, uint32_t color);
 

include/dangerzone/render/text.h

@@ -1,9 +1,12 @@
 #pragma once
 
+#include <dangerzone/engine.h>
+
 #include <stdint.h>
 
 void
 put_char(
+    framebuffer_e framebuffer,
 	char c,
 	uint32_t x, 
 	uint32_t y,
@@ -14,6 +17,7 @@ put_char(
 
 void
 put_string(
+    framebuffer_e framebuffer,
     const char *text,
     uint32_t x,
     uint32_t y,

src/engine/engine.c

@@ -2,6 +2,8 @@
 
 #include "internal/engine_internal.h"
 
+#include <stdlib.h>
+
 engine_internal_state_t *internal_state = NULL;
 game_state_t *game_state = NULL;
 
@@ -42,9 +44,15 @@ mark_dirty_rect(int x, int y, int w, int h)
         .h = h
     };
 
-    if (!game_state->framebuffer_dirty) {
+    if (!game_state->framebuffer_base_dirty) {
         game_state->dirty_rect = rect;
-        game_state->framebuffer_dirty = true;
+        game_state->framebuffer_base_dirty = true;
+        return;
+    }
+    
+    if (!game_state->framebuffer_overdraw_dirty) {
+        game_state->dirty_rect = rect;
+        game_state->framebuffer_overdraw_dirty = true;
         return;
     }
 
@@ -83,9 +91,24 @@ mark_dirty_rect(int x, int y, int w, int h)
 }
 
 bool
-upload_dirty_texture(void)
-{
-    if (!game_state->framebuffer_dirty) {
+upload_dirty_texture(
+    framebuffer_e framebuffer
+) {
+    uint32_t *current_framebuffer;
+    switch (framebuffer) {
+    case BASE:
+        current_framebuffer = game_state->framebuffer_base;
+        break;
+    case OVERDRAW:
+        current_framebuffer = game_state->framebuffer_overdraw;
+        break;
+    default:
+        break;
+    }
+
+    if (!game_state->framebuffer_base_dirty &&
+        !game_state->framebuffer_overdraw_dirty
+    ) {
         return true;
     }
 
@@ -117,7 +140,7 @@ upload_dirty_texture(void)
         (size_t)rect.w * sizeof(uint32_t);
 
     const uint8_t *source =
-        (const uint8_t *)game_state->framebuffer +
+        (const uint8_t *)current_framebuffer +
         (size_t)rect.y * source_pitch +
         (size_t)rect.x * sizeof(uint32_t);
 
@@ -134,7 +157,16 @@ upload_dirty_texture(void)
 
     SDL_UnlockTexture(texture);
 
-    game_state->framebuffer_dirty = false;
+    switch (framebuffer) {
+    case BASE:
+        game_state->framebuffer_base_dirty = false;
+        break;
+    case OVERDRAW:
+        game_state->framebuffer_overdraw_dirty = false;
+        break;
+    default:
+        break;
+    }
 
     return true;
 }
@@ -152,7 +184,8 @@ engine_start() {
 		internal_state->engine_update_framebuffer();
 
 		// update the texture with the modified framebuffer
-		upload_dirty_texture();
+		upload_dirty_texture(BASE);
+		upload_dirty_texture(OVERDRAW);
 
 		SDL_RenderClear(
 			internal_state->sdl_state->renderer
@@ -174,6 +207,7 @@ void
 engine_stop() {
 	engine_sdl_destroy(internal_state->sdl_state);
 	free(internal_state);
-	free(game_state->framebuffer);
+	free(game_state->framebuffer_base);
+	free(game_state->framebuffer_overdraw);
     free(game_state);
 }

src/engine/engine_init.c

@@ -3,6 +3,8 @@
 #include "internal/engine_internal.h"
 #include "internal/util/error.h"
 
+#include <stdlib.h>
+
 bool
 engine_sdl_init_state(
 	engine_sdl_state_t **state,
@@ -160,14 +162,23 @@ engine_init(
 		return RCODE_FAILURE;
 	}
 
-	game_state->framebuffer = (uint32_t *)
+	game_state->framebuffer_base = (uint32_t *)
 		malloc(sizeof(uint32_t) * window_width * window_height);
-	if (game_state->framebuffer == NULL) {
+	if (game_state->framebuffer_base == NULL) {
 		free(internal_state);
 		free(game_state);
 		return RCODE_FAILURE;
 	}
 
+	game_state->framebuffer_overdraw = (uint32_t *)
+		malloc(sizeof(uint32_t) * window_width * window_height);
+	if (game_state->framebuffer_overdraw == NULL) {
+		free(internal_state);
+        free(game_state->framebuffer_base);
+		free(game_state);
+		return RCODE_FAILURE;
+	}
+
 	internal_state->engine_poll_events
 		= engine_poll_events;
 
@@ -181,13 +192,15 @@ engine_init(
 	);
 	if (internal_state->sdl_state == NULL) {
 		free(internal_state);
-		free(game_state->framebuffer);
+		free(game_state->framebuffer_base);
+		free(game_state->framebuffer_overdraw);
 		free(game_state);
 		return RCODE_FAILURE;
 	}
 
 	game_state->is_running = true;
-	game_state->framebuffer_dirty = true;
+	game_state->framebuffer_base_dirty = true;
+	game_state->framebuffer_overdraw_dirty = true;
 	game_state->dirty_rect = (SDL_Rect) {
 	    .x = 0,
 	    .y = 0,

src/engine/render/anim.c

@@ -0,0 +1,89 @@
+#include <dangerzone/render/anim.h>
+
+#include <string.h>
+
+void
+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;
+    }
+
+    anim->count = count;
+    anim->elapsed = 0.0f;
+    anim->duration = duration;
+    anim->active = duration > 0.0f && count > 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 (!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;
+
+    if (dt < 0.0f)
+        dt = 0.0f;
+
+    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/engine/render/misc.c

@@ -2,16 +2,36 @@
 #include <dangerzone/render/misc.h>
 #include <dangerzone/render/rect.h>
 
+#include "internal/engine_internal.h"
 #include "internal/util/error.h"
+
 #include <stdint.h>
 
+// helper function to return the correct pointer to a framebuffer for drawing selection
+uint32_t*
+get_framebuffer(
+    framebuffer_e framebuffer
+) {
+    switch (framebuffer) {
+    case BASE:
+        return game_state->framebuffer_base;
+    case OVERDRAW:
+        return game_state->framebuffer_overdraw;
+    default:
+        return game_state->framebuffer_base;
+    }
+}
+
 // alter a pixel at an imaginary x & y coordinates
 void 
 put_pixel(
+    framebuffer_e framebuffer,
 	unsigned int x, 
 	unsigned int y, 
 	uint32_t color
 ) {
+    uint32_t *current_framebuffer = get_framebuffer(framebuffer);
+
 	uint16_t w = game_state->width;
 	uint16_t h = game_state->height;
 
@@ -21,7 +41,7 @@ put_pixel(
 			"at x = %d, y = %d", x, y
 		);
 	} else {
-		game_state->framebuffer[game_state->width * y + x]
+		current_framebuffer[game_state->width * y + x]
 			= color;
 
 	    mark_dirty_rect(x, y, 1, 1);
@@ -31,12 +51,15 @@ put_pixel(
 // fill the entire framebuffer with a given color
 void
 clear_framebuffer(
+    framebuffer_e framebuffer,
 	uint32_t color
 ) {
+    uint32_t *current_framebuffer = get_framebuffer(framebuffer);
+    
     for (size_t i = 0;
          i < (size_t)game_state->width * game_state->height;
          ++i) {
-        game_state->framebuffer[i] = color;
+        current_framebuffer[i] = color;
     }
 
     mark_dirty_rect(

src/engine/render/rect.c

@@ -10,6 +10,7 @@
  */ 
 void
 put_rect(
+    framebuffer_e framebuffer,
 	uint32_t x, 
 	uint32_t y, 
 	uint32_t w, 
@@ -18,12 +19,13 @@ put_rect(
 ) { 
 	for (int i = x; i < x + w; i++) {
 		for (int j = y; j < y + h; j++) {
-			put_pixel(i, j, color);
+			put_pixel(framebuffer, i, j, color);
 		}
 	}
 	mark_dirty_rect(x, y, w, h);
 }
 
+// TODO: remove, see rect.h
 void
 clear_rect(int x, int y, int w, int h, uint32_t color)
 {
@@ -33,7 +35,7 @@ clear_rect(int x, int y, int w, int h, uint32_t color)
                 px < game_state->width &&
                 py >= 0 &&
                 py < game_state->height) {
-                game_state->framebuffer[
+                game_state->framebuffer_base[
                     py * game_state->width + px
                 ] = color;
             }

src/engine/render/text.c

@@ -81,6 +81,7 @@ static const uint8_t font[128][FONT_ROWS] = {
  */
 void
 put_char(
+    framebuffer_e framebuffer,
     char c,
     uint32_t x,
     uint32_t y,
@@ -107,6 +108,7 @@ put_char(
                     ? fg_color : bg_color;
 
             put_rect(
+                framebuffer,
                 x + col * size,
                 y + row * size,
                 size,
@@ -121,6 +123,7 @@ put_char(
 
 void
 put_string(
+    framebuffer_e framebuffer,
     const char *text,
     uint32_t x,
     uint32_t y,
@@ -137,7 +140,7 @@ put_string(
             x = start_x;
             y += (FONT_ROWS + line_spacing) * size;
         } else {
-            put_char(*text, x, y, size, fg_color, bg_color);
+            put_char(framebuffer, *text, x, y, size, fg_color, bg_color);
             x += (FONT_COLS + spacing) * size;
         }
 

src/examples/2048.c

@@ -1,55 +1,490 @@
 #include <dangerzone/engine.h>
+#include <dangerzone/render/anim.h>
 #include <dangerzone/render/misc.h>
+#include <dangerzone/render/rect.h>
 #include <dangerzone/render/text.h>
 
-// polling events every frame
-void
-client_poll_event()
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <math.h>
+
+#define SIZE 4
+#define MOVE_DURATION 0.12f
+#define BORDER_WIDTH 10
+
+typedef enum {
+    LEFT,
+    RIGHT,
+    UP,
+    DOWN
+} dir_e;
+
+typedef struct {
+    uint32_t value;
+    int row;
+    int col;
+} line_tile_t;
+
+typedef enum {
+    GAME_PLAYING,
+    GAME_WON,
+    GAME_LOST
+} game_status_t;
+
+static game_status_t game_status;
+
+typedef struct {
+    uint32_t area[SIZE][SIZE];
+    dir_e direction;
+    uint32_t score;
+} game_t;
+
+static game_t game;
+
+static anim_t movement;
+static anim_track_t move_tracks[SIZE * SIZE];
+static size_t move_track_count;
+
+static double last_frame_time;
+
+static bool
+board_is_full(void)
 {
-	SDL_Event ev = game_state->event;
+    for (int r = 0; r < SIZE; ++r)
+        for (int c = 0; c < SIZE; ++c)
+            if (game.area[r][c] == 0)
+                return false;
 
-	if (ev.type == SDL_EVENT_QUIT) {
-		game_state->is_running = false;
-	}
-
-	if (ev.type == SDL_EVENT_KEY_DOWN) {
-		switch (ev.key.key) {
-		case SDLK_Q:
-			game_state->is_running = false;
-			break;
-		default:
-			break;
-		}
-	}
+    return true;
 }
 
-// performed every frame
-void
-client_update_framebuffer()
+/* Pixel size is calculated from the current window size while drawing. */
+static uint32_t
+colors(uint32_t number)
 {
-	// single green demo pixel
-	game_state->framebuffer[0] = 0x00FF00;
+    switch (number) {
+    case 0:  return 0xFFFFFF;
+    case 2:  return 0x00FF00;
+    case 4:  return 0xFF0000;
+    case 8:  return 0x0000FF;
+    default: return 0xFFFFFF;
+    }
+}
 
-	clear_framebuffer(0xFFFF00);
-	put_string("Welcome to the most\n*DANGEROUS* 2048 game!",
-		20, 20, 2, 2, 3, 0x000000, 0xFFFF00
-	);
+/* Maps positive values logarithmically: powers of two get evenly spaced hues.
+   Returns 0xRRGGBB. Values outside [min_value, max_value] are clamped. */
+uint32_t
+color_for_value(double value, double min_value, double max_value)
+{
+    if (min_value <= 0.0 || max_value <= min_value || value <= 0.0)
+        return 0xFFFFFF;
+
+    if (value < min_value) value = min_value;
+    if (value > max_value) value = max_value;
+
+    double t = (log2(value) - log2(min_value)) /
+               (log2(max_value) - log2(min_value));
+    
+    t = sqrt(t);  /* accelerates color changes near the low end */
+
+    /* Sweep hue from blue to red in HSV; full saturation and brightness. */
+    // double h = (1.0 - t) * 240.0;
+
+    double exponent = log2(value / min_value);  /* 0 at min_value, 1 per doubling */
+    double h = fmod(20.0 + exponent * 45.0, 360.0);
+
+    double c = 1.0;
+    double x = 1.0 - fabs(fmod(h / 60.0, 2.0) - 1.0);
+    double r, g, b;
+
+    if      (h < 60.0)  { r = c; g = x; b = 0.0; }
+    else if (h < 120.0) { r = x; g = c; b = 0.0; }
+    else if (h < 180.0) { r = 0.0; g = c; b = x; }
+    else                { r = 0.0; g = x; b = c; }
+
+    return ((uint32_t)(r * 255.0) << 16) |
+           ((uint32_t)(g * 255.0) << 8)  |
+            (uint32_t)(b * 255.0);
+}
+
+/*
+ * 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)
+{
+    switch (direction) {
+    case LEFT:
+        *row = line;
+        *col = p;
+        break;
+    case RIGHT:
+        *row = line;
+        *col = SIZE - 1 - p;
+        break;
+    case UP:
+        *row = p;
+        *col = line;
+        break;
+    case DOWN:
+        *row = SIZE - 1 - p;
+        *col = line;
+        break;
+    }
+}
+
+/*
+ * 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
+    };
+}
+
+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
+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 p = 0; p < SIZE; ++p) {
+        int row, col;
+        line_coordinate(direction, line, p, &row, &col);
+
+        uint32_t value = game.area[row][col];
+        if (value != 0) {
+            input[input_count++] = (line_tile_t) {
+                .value = value,
+                .row = row,
+                .col = col
+            };
+        }
+    }
+
+    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;
+            if (merged_value >= 2048)
+                game_status = GAME_WON;
+
+            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 {
+            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];
+    }
+
+    return changed;
+}
+
+static bool
+slide(dir_e direction)
+{
+    if (game_status != GAME_PLAYING || anim_is_active(&movement))
+        return false;
+
+    if (anim_is_active(&movement))
+        return false;
+
+    game.direction = direction;
+    move_track_count = 0;
+
+    bool changed = false;
+
+    for (int line = 0; line < SIZE; ++line) {
+        uint32_t output[SIZE];
+        if (process_line(direction, line, output))
+            changed = true;
+    }
+
+    if (!changed) {
+        move_track_count = 0;
+        return false;
+    }
+
+    return anim_start(&movement, move_tracks, move_track_count,
+                      MOVE_DURATION);
+}
+
+static void
+new_2(void)
+{
+    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;
+            }
+        }
+    }
+
+    if (count == 0)
+        return;
+
+    int pick = rand() % count;
+    game.area[empty_rows[pick]][empty_cols[pick]] = 2;
+}
+
+/* Polling events every frame. */
+void
+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)
+        return;
+
+    switch (ev.key.key) {
+    case SDLK_Q:
+        game_state->is_running = false;
+        break;
+    case SDLK_W:
+    case SDLK_UP:
+        if (game_status == GAME_PLAYING)
+           slide(UP);
+        break;
+    case SDLK_S:
+    case SDLK_DOWN:
+        if (game_status == GAME_PLAYING)
+            slide(DOWN);
+        break;
+    case SDLK_A:
+    case SDLK_LEFT:
+        if (game_status == GAME_PLAYING)
+            slide(LEFT);
+        break;
+    case SDLK_D:
+    case SDLK_RIGHT:
+        if (game_status == GAME_PLAYING)
+            slide(RIGHT);
+        break;
+    default:
+        break;
+    }
+}
+
+static double
+monotonic_seconds(void)
+{
+    struct timespec ts;
+    timespec_get(&ts, TIME_UTC);
+    return (double)ts.tv_sec + (double)ts.tv_nsec / 1e9;
+}
+
+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 = color_for_value((double)value, 2, 131072);
+
+    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)) {
+        if (game_status == GAME_PLAYING) {
+            new_2();
+
+            if (board_is_full())
+                game_status = GAME_LOST;
+        }
+    }
+
+    uint32_t tile_size = game_state->width / SIZE;
+    uint32_t border_width = BORDER_WIDTH;
+
+    clear_framebuffer(OVERDRAW, 0x000000);
+
+    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);
+    
+    if (game_status != GAME_PLAYING) {
+        clear_framebuffer(BASE, 0x000000);
+        const char *message =
+            game_status == GAME_WON ? "YOU WIN!" : "YOU LOSE!";
+
+        put_string(OVERDRAW, message,
+                   0 + border_width * 2,
+                   game_state->height / 2,
+                   6, 1, 12, 0xFFFFFF, 0x000000);
+
+        return;
+    }
+
+    /* Draw all cell backgrounds. */
+    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;
+
+            put_rect(BASE, x, y, side, side, 0xFFFFFF);
+            put_rect(OVERDRAW, x, y, side, side, 0xFFFFFF);
+        }
+    }
+
+    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);
+            }
+        }
+    }
+}
+
+static void
+game_init(void)
+{
+    game_status = GAME_PLAYING;
+    memset(&game, 0, sizeof game);
+    anim_init(&movement);
+    srand((unsigned)time(NULL));
+
+    /* Start with two 2-tiles. */
+    new_2();
+    new_2();
 }
 
 int
-main()
+main(void)
 {
-	// initialize the engine
-	if (engine_init(
-		500, 500,
-		"Dangerous 2048",
-		client_poll_event,
-		client_update_framebuffer
-	)) {
-		engine_start();
-		engine_stop();
-		return 0;
-	} else {
-		return 1;
-	}
+    uint32_t window_width = 500;
+    uint32_t window_height = (uint32_t)(window_width * 1.12f);
+
+    game_init();
+
+    if (engine_init(window_width, window_height,
+                    "Dangerous 2048",
+                    client_poll_event,
+                    client_update_framebuffer)) {
+        engine_start();
+        engine_stop();
+        return 0;
+    }
+
+    return 1;
 }
+

src/examples/CMakeLists.txt

@@ -1,8 +1,9 @@
-add_executable(game_snake snake.c)
-target_link_libraries(game_snake PRIVATE dangerzone_engine)
+#add_executable(game_snake snake.c)
+#target_link_libraries(game_snake PRIVATE dangerzone_engine)
 
 add_executable(game_2048 2048.c)
 target_link_libraries(game_2048 PRIVATE dangerzone_engine)
+target_link_libraries(game_2048 PRIVATE m)
 
-add_executable(game_window window.c)
-target_link_libraries(game_window PRIVATE dangerzone_engine)
+#add_executable(game_window window.c)
+#target_link_libraries(game_window PRIVATE dangerzone_engine)

src/internal/engine_internal.h

@@ -1,9 +1,9 @@
 #pragma once
 
+#include <dangerzone/engine.h>
+
 #include <SDL3/SDL.h>
 #include <stdbool.h>
-#include <stdlib.h>
-#include <string.h>
 #include <stdint.h>
 
 #define WINDOW_NAME_MAX_LENGTH 128
@@ -46,3 +46,8 @@ void
 engine_sdl_destroy(
 	engine_sdl_state_t *state
 );
+
+uint32_t*
+get_framebuffer(
+    framebuffer_e framebuffer
+);