From 3e619979dafa64c6b2576420ff1ce59462256d5e Mon Sep 17 00:00:00 2001
From: P. J. McDermott <pj@pehjota.net>
Date: Tue, 10 Aug 2021 02:08:41 -0400
Subject: char: Add collision detection/handling

---
(limited to 'src')

diff --git a/src/char.h b/src/char.h
index 3e0e0ab..2c31ca2 100644
--- a/src/char.h
+++ b/src/char.h
@@ -39,6 +39,9 @@ int
 mf_char_update(struct mf_char *c);
 
 int
+mf_char_collision(struct mf_char *c1, struct mf_char *c2, int handle);
+
+int
 mf_char_render(struct mf_char *c, SDL_Renderer *renderer);
 
 void
diff --git a/src/char/char.c b/src/char/char.c
index 0ab7145..4a4a4e7 100644
--- a/src/char/char.c
+++ b/src/char/char.c
@@ -126,6 +126,24 @@ mf_char_update(struct mf_char *c)
 }
 
 int
+mf_char_collision(struct mf_char *c1, struct mf_char *c2, int handle)
+{
+	if (c1->cur_x == c2->cur_x && c1->cur_y == c2->cur_y) goto hit;
+	if (c1->cur_x == c2->new_x && c1->cur_y == c2->new_y) goto hit;
+	if (c1->new_x == c2->cur_x && c1->new_y == c2->cur_y) goto hit;
+	if (c1->new_x == c2->new_x && c1->new_y == c2->new_y) goto hit;
+
+	return 0;
+
+ hit:
+	if (handle == SDL_TRUE) {
+		c1->collide(c1);
+		c2->collide(c2);
+	}
+	return 1;
+}
+
+int
 mf_char_render(struct mf_char *c, SDL_Renderer *renderer)
 {
 	int    e   = 0;
diff --git a/src/char/char.h b/src/char/char.h
index f5054d5..02bddaa 100644
--- a/src/char/char.h
+++ b/src/char/char.h
@@ -54,6 +54,7 @@ struct mf_char {
 	int               (*update)(struct mf_char *);
 	int               (*step)(struct mf_char *);
 	int               (*turn)(struct mf_char *);
+	void              (*collide)(struct mf_char *);
 	int               (*render)(struct mf_char *, SDL_Renderer *);
 	void              (*destroy)(struct mf_char *);
 };
@@ -70,6 +71,7 @@ mf_char_new(size_t size);
 		c->update  = &_mf_##name##_update; \
 		c->step    = &_mf_##name##_step; \
 		c->turn    = &_mf_##name##_turn; \
+		c->collide = &_mf_##name##_collide; \
 		c->render  = &_mf_##name##_render; \
 		c->destroy = &_mf_##name##_destroy; \
 		t_c = (struct mf_##name *) c; \
diff --git a/src/char/enemy.c b/src/char/enemy.c
index 82cc16b..fb259a2 100644
--- a/src/char/enemy.c
+++ b/src/char/enemy.c
@@ -97,6 +97,20 @@ _mf_enemy_turn(struct mf_char *c)
 	return 0;
 }
 
+static void
+_mf_enemy_collide(struct mf_char *c)
+{
+	/* Don't go forward unless necessary */
+	switch (c->cur_dir) {
+		case MF_CHAR_DIR_U_: c->cur_dir = MF_CHAR_DIR_D_; break;
+		case MF_CHAR_DIR_D_: c->cur_dir = MF_CHAR_DIR_U_; break;
+		case MF_CHAR_DIR_L_: c->cur_dir = MF_CHAR_DIR_R_; break;
+		case MF_CHAR_DIR_R_: c->cur_dir = MF_CHAR_DIR_L_; break;
+		default:             c->cur_dir = MF_CHAR_DIR_N_; break;
+	}
+	_mf_enemy_step(c);
+}
+
 static int
 _mf_enemy_render(struct mf_char *c __attribute__((__unused__)),
 		SDL_Renderer *renderer __attribute__((__unused__)))
diff --git a/src/char/player.c b/src/char/player.c
index eff0dbd..fdeac5c 100644
--- a/src/char/player.c
+++ b/src/char/player.c
@@ -74,6 +74,11 @@ _mf_player_render(struct mf_char *c __attribute__((__unused__)),
 }
 
 static void
+_mf_player_collide(struct mf_char *c __attribute__((__unused__)))
+{
+}
+
+static void
 _mf_player_destroy(struct mf_char *c __attribute__((__unused__)))
 {
 }
diff --git a/src/game.c b/src/game.c
index 5daea66..0c94202 100644
--- a/src/game.c
+++ b/src/game.c
@@ -156,6 +156,7 @@ mf_game(long seed, int size, int fow, int reveal, int enemies,
 	int                  fr;
 	int                  won;
 	Uint32               beg;
+	int                  j;
 	int                  secs;
 	Uint32               end;
 	Uint32               delay;
@@ -246,6 +247,12 @@ mf_game(long seed, int size, int fow, int reveal, int enemies,
 			for (i = 0; i < 1 + enemies; ++i) {
 				mf_char_update(chars[i]);
 			}
+			for (i = 1; i < 1 + enemies; ++i) {
+				for (j = i + 1; j < 1 + enemies; ++j) {
+					mf_char_collision(chars[i], chars[j],
+							SDL_TRUE);
+				}
+			}
 			mf_char_get_vector(chars[0], &game.player_cx,
 					&game.player_cy, &game.player_travel,
 					&game.player_dx, &game.player_dy);
--
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