From 9b6595477616a8904ade43ff472f9c18fafb3555 Mon Sep 17 00:00:00 2001
From: Florian Sylvain <sylvainflorian@proton.me>
Date: Sun, 11 May 2025 01:41:19 +0200
Subject: [PATCH] feat: batched debug lines draws

---
 src/DebugDraw.cpp | 25 +++++++++++++++----------
 src/DebugDraw.hpp | 14 +++++++++-----
 src/Game.cpp      | 11 ++++++++---
 src/Game.hpp      |  2 ++
 4 files changed, 34 insertions(+), 18 deletions(-)

diff --git a/src/DebugDraw.cpp b/src/DebugDraw.cpp
index 4366af7..75108cd 100644
--- a/src/DebugDraw.cpp
+++ b/src/DebugDraw.cpp
@@ -10,26 +10,26 @@ float clamp(float value, float minVal, float maxVal) {
     return std::max(minVal, std::min(value, maxVal));
 }
 
-void DebugDraw::drawLine(sf::RenderWindow& window, const sf::Vector2f& start,
-                         const sf::Vector2f& direction, float length,
-                         const sf::Color& color) {
+void DebugDraw::addLine(sf::VertexArray& lines, const sf::Vector2f& start,
+                        const sf::Vector2f& direction, float length,
+                        const sf::Color& color) {
     sf::Vector2f endPoint = start + VectorMath::normalize(direction) * length;
-    sf::Vertex line[] = {{start, color}, {endPoint, color}};
-
-    window.draw(line, 2, sf::PrimitiveType::Lines);
+    lines.append(sf::Vertex({start, color}));
+    lines.append(sf::Vertex({endPoint, color}));
 }
 
-void DebugDraw::drawDirectionLine(sf::RenderWindow& window, const Ball* ball) {
+void DebugDraw::addDirectionLine(sf::VertexArray& lines, const Ball* ball,
+                                 const sf::RenderWindow& window) {
     sf::Vector2f ballCenter = ball->getPosition();
     sf::Vector2i mousePixel = sf::Mouse::getPosition(window);
     sf::Vector2f mouseWorld(static_cast<float>(mousePixel.x),
                             static_cast<float>(mousePixel.y));
     sf::Vector2f dir = mouseWorld - ballCenter;
 
-    drawLine(window, ballCenter, dir, 100.f, sf::Color::Green);
+    addLine(lines, ballCenter, dir, 100.f, sf::Color::Green);
 }
 
-void DebugDraw::drawVelocityLine(sf::RenderWindow& window, const Ball* ball) {
+void DebugDraw::addVelocityLine(sf::VertexArray& lines, const Ball* ball) {
     if (ball->isAtRest()) return;
 
     sf::Vector2f ballCenter = ball->getPosition();
@@ -37,5 +37,10 @@ void DebugDraw::drawVelocityLine(sf::RenderWindow& window, const Ball* ball) {
     float velLength = VectorMath::length(velocity);
     float clampedLength = std::max(0.f, std::min(velLength, 100.f));
 
-    drawLine(window, ballCenter, velocity, clampedLength, sf::Color::Blue);
+    addLine(lines, ballCenter, velocity, clampedLength, sf::Color::Blue);
+}
+
+void DebugDraw::drawBatchedLines(sf::RenderWindow& window,
+                                 const sf::VertexArray& lines) {
+    if (lines.getVertexCount() > 0) window.draw(lines);
 }
diff --git a/src/DebugDraw.hpp b/src/DebugDraw.hpp
index a24f098..4c313c1 100644
--- a/src/DebugDraw.hpp
+++ b/src/DebugDraw.hpp
@@ -1,14 +1,18 @@
 #pragma once
 #include <SFML/Graphics/Color.hpp>
 #include <SFML/Graphics/RenderWindow.hpp>
+#include <SFML/Graphics/VertexArray.hpp>
 
 #include "Ball.hpp"
 
 class DebugDraw {
    public:
-    static void drawLine(sf::RenderWindow& window, const sf::Vector2f& start,
-                         const sf::Vector2f& direction, float length,
-                         const sf::Color& color);
-    static void drawDirectionLine(sf::RenderWindow& window, const Ball* ball);
-    static void drawVelocityLine(sf::RenderWindow& window, const Ball* ball);
+    static void addLine(sf::VertexArray& lines, const sf::Vector2f& start,
+                        const sf::Vector2f& direction, float length,
+                        const sf::Color& color);
+    static void addDirectionLine(sf::VertexArray& lines, const Ball* ball,
+                                 const sf::RenderWindow& window);
+    static void addVelocityLine(sf::VertexArray& lines, const Ball* ball);
+    static void drawBatchedLines(sf::RenderWindow& window,
+                                 const sf::VertexArray& lines);
 };
diff --git a/src/Game.cpp b/src/Game.cpp
index 2013520..8fe1b8f 100644
--- a/src/Game.cpp
+++ b/src/Game.cpp
@@ -11,7 +11,8 @@
 Game::Game()
     : m_inputManager(
           std::bind(&Game::processKeyPressed, this, std::placeholders::_1),
-          std::bind(&Game::processMousePressed, this, std::placeholders::_1)) {
+          std::bind(&Game::processMousePressed, this, std::placeholders::_1)),
+      m_debugLines(sf::PrimitiveType::Lines) {
     m_window.create(sf::VideoMode({Constants::WIDTH, Constants::HEIGHT}),
                     "SFML Playground");
     m_window.setVerticalSyncEnabled(true);
@@ -58,16 +59,20 @@ void Game::update() {
 void Game::render() {
     m_window.clear(sf::Color::Black);
 
+    m_debugLines.clear();
+
     for (const auto &object : m_objects) {
         object->draw(m_window);
 
         auto *ball = dynamic_cast<Ball *>(object.get());
         if (!ball) continue;
 
-        DebugDraw::drawDirectionLine(m_window, ball);
-        DebugDraw::drawVelocityLine(m_window, ball);
+        DebugDraw::addDirectionLine(m_debugLines, ball, m_window);
+        DebugDraw::addVelocityLine(m_debugLines, ball);
     }
 
+    DebugDraw::drawBatchedLines(m_window, m_debugLines);
+
     m_window.display();
 }
 
diff --git a/src/Game.hpp b/src/Game.hpp
index 68d9c4e..2a84a90 100644
--- a/src/Game.hpp
+++ b/src/Game.hpp
@@ -1,5 +1,6 @@
 #pragma once
 #include <SFML/Graphics/RenderWindow.hpp>
+#include <SFML/Graphics/VertexArray.hpp>
 #include <SFML/System/Clock.hpp>
 #include <SFML/System/Vector2.hpp>
 #include <SFML/Window/Event.hpp>
@@ -20,6 +21,7 @@ class Game {
     std::vector<std::unique_ptr<PhysicalObject>> m_objects;
     sf::Clock m_clock;
     InputManager m_inputManager;
+    sf::VertexArray m_debugLines;
     void processKeyPressed(const sf::Event::KeyPressed& keyPressed);
     void processMousePressed(const sf::Event::MouseButtonPressed& mousePressed);
     void handleMouseClick(const sf::Vector2i& mousePos);