From 98c3bbf3f909f18bdfd03351f72c0a0a3213293c Mon Sep 17 00:00:00 2001
From: Florian Sylvain <sylvainflorian@proton.me>
Date: Sun, 11 May 2025 04:36:24 +0200
Subject: [PATCH] feat: dynamic color update to Ball based on velocity

---
 src/Ball.cpp      | 46 +++++++++++++++++++++++++++++++++++++++++++++-
 src/Ball.hpp      |  3 ++-
 src/Constants.hpp |  2 +-
 3 files changed, 48 insertions(+), 3 deletions(-)

diff --git a/src/Ball.cpp b/src/Ball.cpp
index 6f97af1..c49fd53 100644
--- a/src/Ball.cpp
+++ b/src/Ball.cpp
@@ -9,7 +9,8 @@ Ball::Ball(float radius, const sf::Vector2f& pos, const sf::Vector2f& vel,
     : m_radius(radius),
       m_velocity(vel),
       m_lastPosition(pos),
-      m_pixelVelocity(vel) {
+      m_pixelVelocity(vel),
+      m_baseColor(color) {
     m_shape.setRadius(radius);
     m_shape.setOrigin(sf::Vector2f(radius, radius));
     m_shape.setPosition(pos);
@@ -25,9 +26,52 @@ void Ball::update(float dt, const sf::Vector2f& windowSize) {
     m_pixelVelocity = (currentPosition - m_lastPosition) / dt;
     m_lastPosition = currentPosition;
 
+    updateColor();
     handleWallCollision(windowSize);
 }
 
+void Ball::updateColor() {
+    float speed =
+        std::sqrt(m_velocity.x * m_velocity.x + m_velocity.y * m_velocity.y);
+
+    const float MAX_SPEED = 2000.0f;
+    float t = std::min(speed / MAX_SPEED, 1.0f);
+
+    sf::Color targetColor;
+
+    if (t < 0.33f) {
+        float scaledT = t * 3.0f;
+        targetColor.r = static_cast<std::uint8_t>(0 + scaledT * 128);
+        targetColor.g = static_cast<std::uint8_t>(0);
+        targetColor.b = static_cast<std::uint8_t>(255);
+    } else if (t < 0.66f) {
+        float scaledT = (t - 0.33f) * 3.0f;
+        targetColor.r = static_cast<std::uint8_t>(128 + scaledT * 127);
+        targetColor.g = static_cast<std::uint8_t>(0 + scaledT * 165);
+        targetColor.b = static_cast<std::uint8_t>(255 - scaledT * 255);
+    } else {
+        float scaledT = (t - 0.66f) * 3.0f;
+        targetColor.r = static_cast<std::uint8_t>(255);
+        targetColor.g = static_cast<std::uint8_t>(165 - scaledT * 165);
+        targetColor.b = static_cast<std::uint8_t>(0);
+    }
+
+    sf::Color currentColor = m_shape.getFillColor();
+
+    const float TRANSITION_SPEED = 0.05f;
+
+    sf::Color newColor;
+    newColor.r = static_cast<std::uint8_t>(
+        currentColor.r + TRANSITION_SPEED * (targetColor.r - currentColor.r));
+    newColor.g = static_cast<std::uint8_t>(
+        currentColor.g + TRANSITION_SPEED * (targetColor.g - currentColor.g));
+    newColor.b = static_cast<std::uint8_t>(
+        currentColor.b + TRANSITION_SPEED * (targetColor.b - currentColor.b));
+    newColor.a = 255;
+
+    m_shape.setFillColor(newColor);
+}
+
 void Ball::draw(sf::RenderWindow& window) { window.draw(m_shape); }
 
 void Ball::applyImpulse(const sf::Vector2f& impulse) {
diff --git a/src/Ball.hpp b/src/Ball.hpp
index 3219d08..f16ba2d 100644
--- a/src/Ball.hpp
+++ b/src/Ball.hpp
@@ -11,8 +11,9 @@ class Ball : public PhysicalObject {
     bool m_atRest = false;
     sf::Vector2f m_lastPosition;
     sf::Vector2f m_pixelVelocity;
-
+    sf::Color m_baseColor;
     void handleWallCollision(const sf::Vector2f& windowSize);
+    void updateColor();
 
    public:
     Ball(float radius, const sf::Vector2f& pos, const sf::Vector2f& vel,
diff --git a/src/Constants.hpp b/src/Constants.hpp
index f639dab..ab2883c 100644
--- a/src/Constants.hpp
+++ b/src/Constants.hpp
@@ -9,5 +9,5 @@ constexpr float FRICTION = 0.9f;
 constexpr float BALL_RADIUS = 20.f;
 constexpr float IMPULSE = 2500.f;
 constexpr float REST_PIXEL_VELOCITY = 2.0f;
-constexpr unsigned BALL_QUANTITY = 500;
+constexpr unsigned BALL_QUANTITY = 100;
 }  // namespace Constants