Add Bat enemy

4 files changed, 104 insertions, 1 deletions

diff --git a/src/bat.c b/src/bat.c
new file mode 100644
index 0000000..73ea4b2
--- /dev/null
+++ b/src/bat.c
@@ -0,0 +1,94 @@
+#include <stdint.h>
+
+#include <vga.h>
+#include "map.h"
+#include "entities.h"
+
+#include "player.h"
+
+#include "bat.h"
+
+#define DIR_UP 0
+#define DIR_DOWN 1
+
+/* limit of the animation cycle */
+#define MAX_FRAME 4
+
+static const Rect frames[2 * 4] =
+{
+    /* right */
+    { 64, 32, 144, 144 },
+    { 80, 32, 144, 144 },
+    { 96, 32, 144, 144 },
+    { 80, 32, 144, 144 },
+
+    /* left */
+    { 64, 32, 144, 144 },
+    { 80, 32, 144, 144 },
+    { 96, 32, 144, 144 },
+    { 80, 32, 144, 144 },
+};
+
+void bat_init(Entity *e)
+{
+    e->frames = (const Rect *)frames;
+    e->update = bat_update;
+    /* will control vertical movement */
+    e->flags = DIR_UP;
+}
+
+void bat_update(Entity *e)
+{
+    if (e->delay & 1)
+    {
+        /* horizontal */
+        if (e->dir == DIR_RIGHT)
+        {
+            if (map_is_blocked(e->x + 16, e->y + 7))
+                e->dir = DIR_LEFT;
+            else
+                e->x++;
+        }
+        else
+        {
+            /* dir is LEFT */
+            if (map_is_blocked(e->x - 1, e->y + 7))
+                e->dir = DIR_RIGHT;
+            else
+                e->x--;
+        }
+
+        /* vertical */
+        if (e->flags == DIR_DOWN)
+        {
+            if (map_is_blocked(e->x + 7, e->y + 16))
+                e->flags = DIR_UP;
+            else
+                e->y++;
+        }
+        else
+        {
+            /* dir is UP */
+            if (map_is_blocked(e->x + 7, e->y - 1))
+                e->flags = DIR_DOWN;
+            else
+                e->y--;
+        }
+    }
+
+    if (player_collision(e))
+    {
+        player_hit();
+        /* change direction */
+        e->dir ^= 1;
+        e->flags ^= 1;
+    }
+
+    if (e->delay++ == WALK_DELAY - 2)
+    {
+        e->delay = 0;
+        e->frame++;
+        if (e->frame == MAX_FRAME)
+            e->frame = 0;
+    }
+}
diff --git a/src/bat.h b/src/bat.h
new file mode 100644
index 0000000..cf21e8a
--- /dev/null
+++ b/src/bat.h
@@ -0,0 +1,7 @@
+#ifndef _BAT_H
+#define _BAT_H
+
+void bat_init(Entity *e);
+void bat_update(Entity *e);
+
+#endif /* _BAT_H */
diff --git a/src/entities.h b/src/entities.h
index e553390..016dcd2 100644
--- a/src/entities.h
+++ b/src/entities.h
@@ -15,7 +15,7 @@ typedef struct entity_s
     uint8_t frame;
     uint8_t delay;
     uint8_t gravity;
-    uint8_t flag;
+    uint8_t flags;
     uint8_t bg[16 * 16];
     /* expected to be 2 directions per 4 frames max; 8 Rect */
     const Rect *frames;
diff --git a/src/map.c b/src/map.c
index c62c5c1..f7c271b 100644
--- a/src/map.c
+++ b/src/map.c
@@ -9,6 +9,7 @@
 #include "entities.h"
 #include "player.h"
 #include "snake.h"
+#include "bat.h"
 
 #include "map.h"
 
@@ -26,6 +27,7 @@ static uint8_t total_gold;
 static void (* const init[])(Entity *) =
 {
     snake_init,
+    bat_init,
 };
 
 void map_init(const uint8_t map[])