From 550869b194433fa07ac7554acef0954a9df9ba79 Mon Sep 17 00:00:00 2001
From: commandblockguy <commandblockguy1@gmail.com>
Date: Mon, 18 Jan 2021 00:40:04 -0600
Subject: [PATCH] Rework how objects get killed

---
 src/game.cpp                  | 12 ++++++------
 src/globals.h                 |  1 -
 src/objects/mine.cpp          | 22 ++++++++++++++--------
 src/objects/mine.h            |  2 ++
 src/objects/mine_detector.cpp |  7 ++-----
 src/objects/physicsbody.cpp   | 33 +++++++++++++++++++++------------
 src/objects/physicsbody.h     |  4 +++-
 src/objects/shell.cpp         | 10 ++++++++--
 src/objects/shell.h           |  4 ++++
 src/objects/tank.cpp          | 10 +++++-----
 src/objects/tank.h            |  2 ++
 11 files changed, 67 insertions(+), 40 deletions(-)

diff --git a/src/game.cpp b/src/game.cpp
index 4078660..dbbae3e 100644
--- a/src/game.cpp
+++ b/src/game.cpp
@@ -13,10 +13,10 @@
 bool start_mission(const serialized_tank_t *ser_tanks) {
     dbg_printf("starting mission\n");
 
-    while(!PhysicsBody::objects.empty()) {
-        // Delete objects without killing
-        delete PhysicsBody::objects[0];
+    for(auto & obj : PhysicsBody::objects) {
+        obj->active = false;
     }
+    PhysicsBody::remove_inactive();
 
     game.num_tanks = 0;
 
@@ -67,9 +67,11 @@ uint8_t play_mission(const serialized_tank_t *ser_tanks) {
         for(auto & object : PhysicsBody::objects) {
             object->tick();
         }
+        PhysicsBody::remove_inactive();
+        PhysicsBody::sort();
         profiler_end(physics);
 
-        if(!game.player_alive) {
+        if(!game.player) {
             profiler_end(total);
             game.lives--;
             if(!game.lives) {
@@ -84,8 +86,6 @@ uint8_t play_mission(const serialized_tank_t *ser_tanks) {
             return NEXT_LEVEL;
         }
 
-        PhysicsBody::sort();
-
         render();
 
         game.tick++;
diff --git a/src/globals.h b/src/globals.h
index 4235f7e..0a5ac85 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -16,7 +16,6 @@ typedef struct {
     uint8_t lives; //Number of remaining tanks. This includes the tank that is currently in use, so a value of 1 means that the game will end the next time the tank is hit.
     uint8_t total_kills; //Number of enemy tanks destroyed.
     uint8_t kills[NUM_TANK_TYPES];
-    bool player_alive;
     uint8_t num_tanks;
     bool alive_tanks[MAX_NUM_TANKS];
     Tank *player;
diff --git a/src/objects/mine.cpp b/src/objects/mine.cpp
index 25c1d5e..c7b2df4 100644
--- a/src/objects/mine.cpp
+++ b/src/objects/mine.cpp
@@ -20,9 +20,6 @@ Mine::Mine(Tank *tank) {
     position_x = tank->position_x + (TANK_SIZE - MINE_SIZE) / 2;
     position_y = tank->position_y + (TANK_SIZE - MINE_SIZE) / 2;
 
-    velocity_x = 0;
-    velocity_y = 0;
-
     parent = tank;
 
     new (std::nothrow) MineDetector(this);
@@ -45,7 +42,7 @@ void Mine::process() {
         detonate();
     }
     if(countdown == 0) {
-        kill();
+        active = false;
     }
 
 //todo: range detection
@@ -91,6 +88,11 @@ void Mine::render(uint8_t layer) {
 }
 
 void Mine::detonate() {
+    if(countdown < EXPLOSION_ANIM) {
+        // Don't explode multiple times
+        return;
+    }
+
     countdown = EXPLOSION_ANIM - 1;
 
     // todo: The original game uses a radius, not a square
@@ -107,15 +109,19 @@ void Mine::detonate() {
     }
 
     // Kill any nearby physics objects
-    for(auto *it = objects.begin(); it < objects.end();) {
-        if(*it != this && center_distance_less_than(*it, MINE_EXPLOSION_RADIUS)) {
-            (**it).kill();
-        } else it++;
+    for(auto & obj : objects) {
+        if(obj != this && center_distance_less_than(obj, MINE_EXPLOSION_RADIUS)) {
+            obj->handle_explosion();
+        }
     }
 
     generate_bg_tilemap();
 }
 
+void Mine::handle_explosion() {
+    detonate();
+}
+
 void Mine::handle_collision(PhysicsBody *other) {
     other->collide(this);
 }
diff --git a/src/objects/mine.h b/src/objects/mine.h
index 9e6c82f..2fc01c2 100644
--- a/src/objects/mine.h
+++ b/src/objects/mine.h
@@ -43,6 +43,8 @@ class Mine: public PhysicsBody {
 
     void detonate();
 
+    void handle_explosion();
+
     void handle_collision(PhysicsBody *other);
     void collide(Tank *tank);
     void collide(Shell *shell);
diff --git a/src/objects/mine_detector.cpp b/src/objects/mine_detector.cpp
index 38357f0..bc1a8fd 100644
--- a/src/objects/mine_detector.cpp
+++ b/src/objects/mine_detector.cpp
@@ -13,14 +13,11 @@ MineDetector::MineDetector(Mine *mine) {
     position_x = mine->center_x() - MINE_EXPLOSION_RADIUS;
     position_y = mine->center_y() - MINE_EXPLOSION_RADIUS;
 
-    velocity_x = 0;
-    velocity_y = 0;
-
     parent = mine;
 }
 
 void MineDetector::process() {
-    if(!parent) kill();
+    if(!parent) active = false;
 
     if(!primed) {
         Tank *placer = (Tank*)parent->parent;
@@ -43,7 +40,7 @@ void MineDetector::collide(__attribute__((unused)) Tank *tank) {
         if(parent) {
             ((Mine*)parent)->countdown = MINE_TRIGGERED;
         }
-        kill();
+        active = false;
     }
 }
 
diff --git a/src/objects/physicsbody.cpp b/src/objects/physicsbody.cpp
index 9ce72fd..2fcbddc 100644
--- a/src/objects/physicsbody.cpp
+++ b/src/objects/physicsbody.cpp
@@ -16,6 +16,11 @@ uint PhysicsBody::center_y() const {
 }
 
 PhysicsBody::PhysicsBody() {
+    active = true;
+    parent = nullptr;
+    velocity_x = 0;
+    velocity_y = 0;
+
     // todo: compiler bug triggers if this line is the only thing in here
     objects.push_back(this);
 
@@ -24,19 +29,7 @@ PhysicsBody::PhysicsBody() {
 }
 
 PhysicsBody::~PhysicsBody() {
-    // Remove from object list
-    for(auto *it = objects.begin(); it < objects.end();) {
-        // Inform any children that we no longer exist
-        if((**it).parent == this) (**it).parent = nullptr;
-        // Remove from objects list
-        if(*it == this) {
-            objects.erase(it);
-        } else it++;
-    }
-}
 
-void PhysicsBody::kill() {
-    delete this;
 }
 
 void PhysicsBody::sort() {
@@ -52,6 +45,18 @@ void PhysicsBody::sort() {
     }
 }
 
+void PhysicsBody::remove_inactive() {
+    for(auto & obj : objects) {
+        if(!obj->parent->active) obj->parent = nullptr;
+    }
+    for(auto *it = objects.begin(); it < objects.end();) {
+        if(!(*it)->active) {
+            delete *it;
+            it = objects.erase(it);
+        } else it++;
+    }
+}
+
 bool PhysicsBody::detect_collision(PhysicsBody *other) const {
     return position_x < other->position_x + (int)other->width &&
            position_x + (int)width > other->position_x &&
@@ -172,3 +177,7 @@ void PhysicsBody::tick() {
 void PhysicsBody::handle_tile_collision(__attribute__((unused)) direction_t dir) {
 
 }
+
+void PhysicsBody::handle_explosion() {
+    // Do nothing, by default
+}
diff --git a/src/objects/physicsbody.h b/src/objects/physicsbody.h
index 5fae6df..7c51b1b 100644
--- a/src/objects/physicsbody.h
+++ b/src/objects/physicsbody.h
@@ -24,6 +24,7 @@ class PhysicsBody {
     uint width;
     uint height;
     PhysicsBody *parent;
+    bool active;
 
     bool tile_collisions;
     // Whether or not to collide with holes
@@ -44,12 +45,13 @@ class PhysicsBody {
     void tick();
 
     static void sort();
+    static void remove_inactive();
 
-    virtual void kill();
     virtual void process() = 0;
     virtual void render(uint8_t layer);
 
     virtual void handle_tile_collision(direction_t dir);
+    virtual void handle_explosion();
 
     // Polymorphic ping-pong (aka "visitor pattern," apparently)
     virtual void handle_collision(PhysicsBody *other) = 0;
diff --git a/src/objects/shell.cpp b/src/objects/shell.cpp
index 66e135f..565feba 100644
--- a/src/objects/shell.cpp
+++ b/src/objects/shell.cpp
@@ -35,7 +35,6 @@ Shell::Shell(Tank *tank) {
 
 Shell::~Shell() {
     if(parent) {
-        // todo: see if there's a way to do this without an ugly cast
         ((Tank*)parent)->num_shells--;
     }
 }
@@ -70,6 +69,10 @@ void Shell::update_direction() {
     direction = angle_to_shell_direction(angle);
 }
 
+void Shell::handle_explosion() {
+    kill();
+}
+
 void Shell::handle_collision(PhysicsBody *other) {
     other->collide(this);
 }
@@ -99,7 +102,6 @@ void Shell::handle_tile_collision(direction_t dir) {
         return;
     }
 
-    //shell_t is still alive
     if(dir & UP || dir & DOWN) {
         velocity_y *= -1;
         update_direction();
@@ -115,3 +117,7 @@ void Shell::handle_tile_collision(direction_t dir) {
 void Shell::collide(__attribute__((unused)) MineDetector *detector) {
     // don't do anything
 }
+
+void Shell::kill() {
+    active = false;
+}
diff --git a/src/objects/shell.h b/src/objects/shell.h
index 2a559a1..4870de8 100644
--- a/src/objects/shell.h
+++ b/src/objects/shell.h
@@ -41,6 +41,10 @@ class Shell: public PhysicsBody {
         return ((uint8_t) -((angle >> (INT_BITS - 8)) - 64)) >> 4;
     }
 
+    void kill();
+
+    void handle_explosion();
+
     void handle_collision(PhysicsBody *other);
     void collide(Tank *tank);
     void collide(Shell *shell);
diff --git a/src/objects/tank.cpp b/src/objects/tank.cpp
index 4175cf6..6b2e57c 100644
--- a/src/objects/tank.cpp
+++ b/src/objects/tank.cpp
@@ -42,8 +42,6 @@ Tank::Tank(const serialized_tank_t *ser_tank, uint8_t id) {
     start_y = ser_tank->start_y + 1;
     position_x = TILE_TO_X_COORD(start_x);
     position_y = TILE_TO_Y_COORD(start_y);
-    velocity_x = 0;
-    velocity_y = 0;
     barrel_rot = 0;
     tread_rot = 0;
     shot_cooldown = 0;
@@ -51,7 +49,6 @@ Tank::Tank(const serialized_tank_t *ser_tank, uint8_t id) {
 
     if(id == 0) {
         game.player = this;
-        game.player_alive = true;
     }
 
     game.num_tanks++;
@@ -60,7 +57,6 @@ Tank::Tank(const serialized_tank_t *ser_tank, uint8_t id) {
 Tank::~Tank() {
     game.num_tanks--;
     if(this == game.player) {
-        game.player_alive = false;
         game.player = nullptr;
     }
 }
@@ -72,7 +68,7 @@ void Tank::kill() {
         game.alive_tanks[id] = false;
     }
 
-    delete this;
+    active = false;
 }
 
 void Tank::process() {
@@ -173,6 +169,10 @@ void Tank::handle_collision(PhysicsBody *other) {
     other->collide(this);
 }
 
+void Tank::handle_explosion() {
+    kill();
+}
+
 void Tank::collide(Tank *tank) {
     //Figure out if the four corners are colliding
     bool top_right = tank->is_point_inside(position_x + width, position_y);
diff --git a/src/objects/tank.h b/src/objects/tank.h
index 0399ef0..e1dfdcf 100644
--- a/src/objects/tank.h
+++ b/src/objects/tank.h
@@ -86,6 +86,8 @@ class Tank: public PhysicsBody {
     static const uint8_t max_mines[];
     static const uint8_t velocities[];
 
+    void handle_explosion();
+
     void handle_collision(PhysicsBody *other);
     void collide(Tank *tank);
     void collide(Shell *shell);