Add armour items

game.c

@@ -35,11 +35,19 @@
 #define ARROW_HEIGHT 4
 #define COUNTER_MASK (1 << 6)
 
+#define ITEM_SPAWN_R 0.9
+#define ITEM_COLLIDE_R 0.025
+#define ITEM_SPAWN_EXP_S 40
+#define ITEM_MIN_SCORE 32
+
+#define ARMOUR_COEFF 5e-6
+
 #define NELEMS(arr) (sizeof(arr) / sizeof(arr[0]))
 
 enum {
 	SHOT_COLLIDE_PRIOR = 1,
 	SHIP_COLLIDE_PRIOR,
+	ITEM_COLLIDE_PRIOR,
 };
 
 static const vec2_t ship_verts[] = {
@@ -61,6 +69,12 @@ static const vec2_t arrow_verts[][MAX_VERTS] = {
 };
 static const unsigned arrow_counts[NELEMS(arrow_verts)] = { 3, 2 };
 
+static const vec2_t item_verts[][MAX_VERTS] = {
+	{ { -0.025, -0.025 }, { 0.025, 0.025 } },
+	{ { -0.025, 0.025 }, { 0.025, -0.025 } },
+};
+static const unsigned item_counts[NELEMS(item_verts)] = { 2, 2 };
+
 static const vec2_t shot_vel = { 0, SHOT_VEL };
 
 static const asteroid_size_dist_entry_t easy_dist[] = {
@@ -85,6 +99,9 @@ static bool paused;
 static unsigned asteroid_count;
 static uint8_t counter;
 static unsigned score;
+static char *msg;
+static unsigned armour_level;
+static bool item;
 
 static void cleared()
 {
@@ -101,6 +118,17 @@ static void die()
 	counter = 0;
 }
 
+static void upgrade_armour()
+{
+	if (armour_level >= 9)
+		return;
+
+	static char armour_msg[] = "ARMOUR X";
+	armour_msg[7] = '0' + ++armour_level;
+	msg = armour_msg;
+	counter = 0;
+}
+
 static void shot_collide(unsigned a, unsigned b, physics_sep_t sep)
 {
 	entity_mark(a);
@@ -112,13 +140,30 @@ static void shot_collide(unsigned a, unsigned b, physics_sep_t sep)
 	}
 }
 
-static void ship_collide(unsigned, unsigned, physics_sep_t)
+static void ship_collide(unsigned a, unsigned b, physics_sep_t sep)
 {
-	die();
+	const float v = sep.va - sep.vb;
+	const float impact = physics_get(b)->mass * v;
+	const float armour = armour_level * ARMOUR_COEFF;
+	if (impact < armour)
+		physics_bounce(a, b, sep);
+	else
+		die();
+}
+
+static void item_collide(unsigned a, unsigned b, physics_sep_t)
+{
+	item = false;
+	entity_mark(a);
+	if (b == ship_entity_id)
+		upgrade_armour();
 }
 
 static void shoot()
 {
+	if (dead || paused)
+		return;
+
 	physics_t *ship = physics_get(ship_entity_id);
 
 	const vec2_t pos
@@ -162,10 +207,12 @@ static void anim_fire(vec2_t *verts)
 
 static void create_field()
 {
+	item = false;
 	dead = false;
 	clear = false;
 	paused = false;
 	asteroid_count = 0;
+	msg = nullptr;
 
 	renderer_set_wrap(true);
 
@@ -200,6 +247,7 @@ static void reset()
 {
 	level = INIT_LEVEL;
 	score = 0;
+	armour_level = 0;
 	asteroids_clear();
 	create_field();
 }
@@ -229,6 +277,24 @@ static void ship_update()
 		win();
 }
 
+static void add_item()
+{
+	const unsigned id = entity_add();
+
+	for (unsigned i = 0; i < NELEMS(item_verts); ++i)
+		scene_add(id, item_verts[i], item_counts[i], false);
+
+	const vec2_t pos = {
+		.x = ITEM_SPAWN_R * rng_plusminus(),
+		.y = ITEM_SPAWN_R * rng_plusminus(),
+	};
+	physics_add(id, pos, MAT2_ID, (vec2_t) {}, 0, 0);
+
+	collisions_add(id, ITEM_COLLIDE_R, ITEM_COLLIDE_PRIOR, item_collide);
+
+	item = true;
+}
+
 void game_init()
 {
 	input_on_shoot(shoot);
@@ -241,8 +307,10 @@ void game_init()
 
 void game_update()
 {
-	if (dead || clear || paused)
+	if (msg != nullptr || dead || clear || paused)
 		++counter;
+	if (counter > COUNTER_MASK)
+		msg = nullptr;
 	if (dead || paused)
 		return;
 
@@ -252,6 +320,11 @@ void game_update()
 	scene_update();
 
 	entities_purge();
+
+	const bool items_enabled = score >= ITEM_MIN_SCORE;
+	if (items_enabled && !item
+	    && rng_canon() < 1.0f / (60 * ITEM_SPAWN_EXP_S))
+		add_item();
 }
 
 void game_draw()
@@ -261,16 +334,20 @@ void game_draw()
 	scene_draw();
 
 	text_draw_score(score);
-
-	if (paused && !(counter & COUNTER_MASK)) {
-		text_draw_centre("PAUSED");
-		return;
-	}
-	if (dead && !(counter & COUNTER_MASK))
-		text_draw_centre("GAME OVER");
-	if (clear) {
+	if (clear)
 		draw_arrow();
-		if (!(counter & COUNTER_MASK))
-			text_draw_centre("CLEAR");
+	const bool display_text = !(counter & COUNTER_MASK);
+	if (display_text) {
+		if (dead)
+			text_draw_centre("GAME OVER");
+		if (clear) {
+			draw_arrow();
+			if (!(counter & COUNTER_MASK))
+				text_draw_centre("CLEAR");
+		}
+		if (paused)
+			text_draw_centre("PAUSED");
+		if (msg != nullptr)
+			text_draw_centre(msg);
 	}
 }