From 7803be09b7c0a133b1009408fea2fb1f1474e786 Mon Sep 17 00:00:00 2001
From: cflip <cflip@cflip.net>
Date: Wed, 30 Mar 2022 21:48:07 -0600
Subject: Store train objects in a unique_ptr

The trains were being destructed after leaving the scope of the
addVehicle function. This change makes sure the trains stay allocated
for the entire lifetime of the level.

Fixes #2
---
 src/level.cpp | 15 +++++++++------
 src/level.h   | 10 ++++++----
 src/main.cpp  |  4 +---
 3 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/src/level.cpp b/src/level.cpp
index e09f74a..22f861b 100644
--- a/src/level.cpp
+++ b/src/level.cpp
@@ -1,6 +1,7 @@
 #include "level.h"
 
 #include <algorithm>
+#include <cstring>
 #include <fstream>
 #include <iostream>
 
@@ -33,8 +34,8 @@ void Level::set(int x, int y, uint8_t tile)
 
 void Level::update()
 {
-	for (auto& vehicle : m_vehicles) {
-		vehicle.update();
+	for (const auto& vehicle : m_vehicles) {
+		vehicle->update();
 	}
 }
 
@@ -77,12 +78,12 @@ void Level::draw(Bitmap& bitmap, int xo, int yo)
 	for (int y = 0; y < m_height; ++y) {
 		for (int x = 0; x < m_width; ++x) {
 			auto isInTile = [x, y](const auto& vehicle) {
-				return vehicle.getSpritePosition().x == x && vehicle.getSpritePosition().y == y;
+				return vehicle->getSpritePosition().x == x && vehicle->getSpritePosition().y == y;
 			};
 
 			auto vehiclesInTile = std::find_if(m_vehicles.begin(), m_vehicles.end(), isInTile);
 			while (vehiclesInTile != m_vehicles.end()) {
-				vehiclesInTile->draw(bitmap, xo, yo);
+				vehiclesInTile->get()->draw(bitmap, xo, yo);
 				vehiclesInTile = std::find_if(++vehiclesInTile, m_vehicles.end(), isInTile);
 			}
 
@@ -97,9 +98,11 @@ void Level::draw(Bitmap& bitmap, int xo, int yo)
 	}
 }
 
-Train& Level::addVehicle()
+void Level::addVehicle(int x, int y)
 {
-	return m_vehicles.emplace_back(*this);
+	auto& ptr = m_vehicles.emplace_back(std::make_unique<Train>(*this));
+	ptr->setPosition(x, y);
+	ptr->setSpeed(0.2f);
 }
 
 void Level::toggleTile(int x, int y)
diff --git a/src/level.h b/src/level.h
index 7bd52e2..fa6376d 100644
--- a/src/level.h
+++ b/src/level.h
@@ -1,10 +1,11 @@
 #pragma once
 
-#include "bitmap.h"
 #include <cstdint>
-#include <cstring>
+#include <memory>
 #include <vector>
 
+#include "bitmap.h"
+
 #define TILE_TYPE(x) ((x)&0xf)
 #define TILE_DATA(x) (x >> 4 & 0xf)
 #define MAKE_TILE(t, d) ((((d)&0xf) << 4) + ((t)&0xf))
@@ -38,17 +39,18 @@ public:
 	void update();
 	void draw(Bitmap& bitmap, int xo, int yo);
 
-	Train& addVehicle();
+	void addVehicle(int x, int y);
 	void toggleTile(int x, int y);
 
 	void save() const;
 	void load();
+
 private:
 	Bitmap& m_tileSprites;
 	int m_width, m_height;
 	uint8_t* m_tiles;
 
-	std::vector<Train> m_vehicles;
+	std::vector<std::unique_ptr<Train>> m_vehicles;
 };
 
 TrackDirection ChooseDirection(Level& level, int x, int y);
diff --git a/src/main.cpp b/src/main.cpp
index dcd5975..25e6fea 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -46,9 +46,7 @@ int main(int argc, char** argv)
 			int my = y / Scale + yOffs;
 			auto pos = ScreenToTile({ mx, my });
 
-			Train& train = level.addVehicle();
-			train.setPosition(pos.x, pos.y);
-			train.setSpeed(0.2f);
+			level.addVehicle(pos.x, pos.y);
 		}
 	});
 
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