Add entity system, add new enemy (snake)

1 files changed, 69 insertions, 0 deletions

diff --git a/src/snake.c b/src/snake.c
new file mode 100644
index 0000000..e81a1c8
--- /dev/null
+++ b/src/snake.c
@@ -0,0 +1,69 @@
+#include <stdint.h>
+
+#include <vga.h>
+#include "map.h"
+#include "entities.h"
+
+#include "player.h"
+
+#include "snake.h"
+
+static const Rect frames[2 * 4] =
+{
+    /* right */
+    { 0, 32, 144, 144 },
+    { 16, 32, 144, 144 },
+    /* not used */
+    { 0, 0, 144, 144 },
+    { 0, 0, 144, 144 },
+
+    /* left */
+    { 32, 32, 144, 144 },
+    { 48, 32, 144, 144 },
+    /* not used */
+    { 0, 0, 144, 144 },
+    { 0, 0, 144, 144 }
+};
+
+void snake_init(Entity *e)
+{
+    e->frames = (const Rect *)frames;
+    e->update = snake_update;
+}
+
+void snake_update(Entity *e)
+{
+    if (e->delay & 1)
+    {
+        if (e->dir == DIR_RIGHT)
+        {
+            if (map_is_blocked(e->x + 16, e->y + 15)
+                    || !map_is_blocked(e->x + 16, e->y + 16))
+                e->dir = DIR_LEFT;
+            else
+                e->x++;
+        }
+        else
+        {
+            /* dir is LEFT */
+            if (map_is_blocked(e->x - 1, e->y + 15)
+                    || !map_is_blocked(e->x - 1, e->y + 16))
+                e->dir = DIR_RIGHT;
+            else
+                e->x--;
+        }
+    }
+
+    if (player_collision(e))
+    {
+        player_hit();
+        /* change direction */
+        e->dir ^= 1;
+    }
+
+    if (e->delay++ == WALK_DELAY + 4)
+    {
+        e->delay = 0;
+        e->frame ^= 1;
+    }
+}