Add gravity

02-jumping-boxes/main.cpp

@@ -3,9 +3,14 @@
 #include <SFML/Audio.hpp>
 #include <SFML/Graphics.hpp>
 
-using Thing = sf::RectangleShape;
-using ThingVector = std::vector<sf::RectangleShape>;
-using ThingIDVector = std::vector<unsigned>;
+struct Thing
+{
+	sf::Vector2f velocity{0, 0};
+	sf::RectangleShape shape{};
+};
+
+using ThingVector = std::vector<Thing>;
+using ThingIDVector = std::vector<uint>;
 
 auto eventsUpdate(
 	sf::RenderWindow &window,
@@ -16,11 +21,19 @@ auto physicsUpdate(
 	const ThingIDVector &dynamicThings,
 	const ThingIDVector &staticThings) -> void;
 
+auto physicsUpdate(
+	ThingVector &things,
+	const sf::Time deltaTime,
+	const ThingIDVector &dynamicThings,
+	const ThingIDVector &staticThings) -> void;
+
 auto physicsTestCollision(
 	Thing &thing,
 	Thing &otherThing) -> void;
 
-auto animationUpdate(ThingVector &things) -> void;
+auto animationUpdate(
+	ThingVector &things,
+	const sf::Time deltaTime) -> void;
 
 auto renderUpdate(
 	sf::RenderWindow &window,
@@ -39,41 +52,45 @@ auto main() -> int
 	camera.setSize(WIDTH, HEIGHT);
 	window.setView(camera);
 
-	// # Create ground
-	Thing ground{sf::Vector2f{4000, 20}};
-	ground.setPosition(-2000, 0);
-	ground.setFillColor(sf::Color::White);
-
-	// # Create players
-	const auto PLAYER_SIZE = sf::Vector2f{50.0f, 50.0f};
-	const auto PLAYER_ORIGIN = sf::Vector2f{PLAYER_SIZE.x / 2.0f, PLAYER_SIZE.y / 2.0f};
-
-	Thing player1;
-	player1.setFillColor(sf::Color::Red);
-	player1.setSize(PLAYER_SIZE);
-	player1.setOrigin(PLAYER_ORIGIN);
-	player1.setPosition(sf::Vector2f{-100, -25});
-
-	Thing player2;
-	player2.setFillColor(sf::Color::Blue);
-	player2.setSize(PLAYER_SIZE);
-	player2.setOrigin(PLAYER_ORIGIN);
-	player2.setPosition(sf::Vector2f{100, -25});
-
-	ThingVector things = {
-		player1,
-		player2,
-		ground,
-	};
-
+	ThingVector things;
 	const ThingIDVector dynamicThings = {0, 1};
 	const ThingIDVector staticThings = {2};
+	{
+		// # Create players
+		const auto PLAYER_SIZE = sf::Vector2f{50.0f, 50.0f};
+		const auto PLAYER_ORIGIN = sf::Vector2f{PLAYER_SIZE.x / 2.0f, PLAYER_SIZE.y / 2.0f};
+
+		Thing player1{};
+		player1.shape.setFillColor(sf::Color::Red);
+		player1.shape.setSize(PLAYER_SIZE);
+		player1.shape.setOrigin(PLAYER_ORIGIN);
+		player1.shape.setPosition(sf::Vector2f{-100, -25});
+		things.emplace_back(player1);
+
+		Thing player2{};
+		player2.shape.setFillColor(sf::Color::Blue);
+		player2.shape.setSize(PLAYER_SIZE);
+		player2.shape.setOrigin(PLAYER_ORIGIN);
+		player2.shape.setPosition(sf::Vector2f{100, -25});
+		things.emplace_back(player2);
+
+		// # Create ground
+		Thing ground{};
+		ground.shape.setSize(sf::Vector2f{4000, 20});
+		ground.shape.setPosition(-2000, 0);
+		ground.shape.setFillColor(sf::Color::White);
+		things.emplace_back(ground);
+	}
 
+	sf::Clock clock; // starts the clock
 	while (window.isOpen())
 	{
+		const auto deltaTime = clock.getElapsedTime();
+		clock.restart();
+
 		eventsUpdate(window, camera);
-		physicsUpdate(things, dynamicThings, staticThings);
-		animationUpdate(things);
+		physicsUpdate(things, deltaTime, dynamicThings, staticThings);
+		animationUpdate(things, deltaTime);
 		renderUpdate(window, things);
 	}
 
@@ -106,12 +123,21 @@ auto eventsUpdate(
 
 auto physicsUpdate(
 	ThingVector &things,
+	const sf::Time deltaTime,
 	const ThingIDVector &dynamicThings,
 	const ThingIDVector &staticThings) -> void
 {
+	const auto GRAVITY = sf::Vector2f{0, 10.0f * 30};
+	const auto dt = deltaTime.asSeconds();
+
 	for (const auto dynamicThingID : dynamicThings)
 	{
 		auto &dynamicThing = things[dynamicThingID];
+		// Add gravity to velocity
+		{
+			dynamicThing.velocity += GRAVITY * dt;
+		}
+
 		for (const auto otherDynamicThingID : dynamicThings)
 		{
 			if (dynamicThingID == otherDynamicThingID)
@@ -133,8 +159,20 @@ auto physicsTestCollision(
 {
 }
 
-auto animationUpdate(ThingVector &things) -> void
+auto animationUpdate(
+	ThingVector &things,
+	const sf::Time deltaTime) -> void
 {
+	for (auto &thing : things)
+	{
+		const auto position = thing.shape.getPosition();
+		const auto velocity = thing.velocity;
+		const auto dt = deltaTime.asSeconds();
+
+		thing.shape.setPosition(
+			position.x + velocity.x * dt,
+			position.y + velocity.y * dt);
+	}
 }
 
 auto renderUpdate(
@@ -144,7 +182,7 @@ auto renderUpdate(
 	window.clear();
 	for (auto &thing : things)
 	{
-		window.draw(thing);
+		window.draw(thing.shape);
 	}
 	window.display();
 }