1 files changed, 103 insertions, 0 deletions
diff --git a/enemy.c b/enemy.c
new file mode 100644
index 0000000..9a67cba
--- /dev/null
+++ b/enemy.c
@@ -0,0 +1,103 @@
+#include "bullet.h"
+#include "components.h"
+#include "game_config.h"
+#include "sprite.h"
+#include "standard.h"
+#include "world.h"
+
+Entity new_skull(World* world, int x, int y) {
+	CSprite* sprite;
+	CPosition* pos;
+	CEnemy* enemy;
+	Entity e;
+
+	e = new_entity(world);
+	add_components(
+		world,
+		e,
+		ctype_position |
+		ctype_sprite |
+		ctype_enemy |
+		ctype_skull
+	);
+	pos = &world->positions[e];
+	sprite = &world->sprites[e];
+	enemy = &world->enemies[e];
+
+	pos->x = x;
+	pos->y = y;
+
+	init_csprite(sprite, sprite_skull_right);
+
+	enemy->hp = skull_hp;
+	enemy->shoot_timer = 0;
+
+	return e;
+}
+
+void enemy_system(World* world) {
+	/* Skulls. */
+	int i;
+	unsigned bits;
+	CPosition* pos;
+	CEnemy* enemy;
+	Player* player;
+	CPosition* ppos;
+	int dpx, dpy, tpx, tpy, d;
+	char buf[32];
+
+	player = &world->player;
+	ppos = &world->positions[player->entity];
+
+	for (i = 0; i < world->entity_count; i++) {
+		bits = world->bitmask[i];
+		if (
+			(bits & ctype_position) &&
+			(bits & ctype_enemy) &&
+			(bits & ctype_skull)
+		) {
+			pos = &world->positions[i];
+			enemy = &world->enemies[i];
+
+			dpx = (ppos->x - pos->x) >> 4;
+			dpy = (ppos->y - pos->y) >> 4;
+			tpx = dpx;
+			tpy = dpy;
+			d = ((dpx * dpx) >> fbits) + ((dpy * dpy) >> fbits);
+
+			if (d < 10 << fbits) {
+				dpx = -dpx;
+				dpy = -dpy;
+				enemy->backpedal = 1;
+			} else if (enemy->backpedal) {
+				if (d > 30 << fbits) {
+					enemy->backpedal = 0;
+				} else {
+					dpx = -dpx;
+					dpy = -dpy;
+				}
+			}
+
+			dpx = (dpx < 0 ? -1 : 1);
+      dpy = (dpy < 0 ? -1 : 1);
+
+			pos->x += dpx * skull_speed;
+			pos->y += dpy * skull_speed;
+
+			if (enemy->shoot_timer > skull_shoot_cooldown) {
+				vec_nrmise(&tpx, &tpy);
+
+				new_enemy_bullet(
+					world,
+					pos->x,
+					pos->y,
+					tpx * enemy_bullet_speed,
+					tpy * enemy_bullet_speed
+				);
+				enemy->shoot_timer = 0;
+			}
+
+			enemy->shoot_timer++;
+		}
+	}
+}