Add polar coordinates constructor for sf::Vector2<T>

examples/tennis/Tennis.cpp

@@ -200,8 +200,7 @@ int main()
             }
 
             // Move the ball
-            float factor = ballSpeed * deltaTime;
+            ball.move({ballSpeed * deltaTime, ballAngle});
-            ball.move({std::cos(ballAngle.asRadians()) * factor, std::sin(ballAngle.asRadians()) * factor});
 
             #ifdef SFML_SYSTEM_IOS
             const std::string inputString = "Touch the screen to restart.";

include/SFML/System/Vector2.hpp

@@ -52,7 +52,7 @@ public:
     constexpr Vector2();
 
     ////////////////////////////////////////////////////////////
-    /// \brief Construct the vector from its coordinates
+    /// \brief Construct the vector from cartesian coordinates
     ///
     /// \param X X coordinate
     /// \param Y Y coordinate
@@ -74,6 +74,22 @@ public:
     template <typename U>
     constexpr explicit Vector2(const Vector2<U>& vector);
 
+    ////////////////////////////////////////////////////////////
+    /// \brief Construct the vector from polar coordinates
+    ///
+    /// \param r   Length of vector (can be negative)
+    /// \param phi Angle from X axis
+    ///
+    /// Note that this constructor is lossy: calling length() and angle()
+    /// may return values different to those provided in this constructor.
+    ///
+    /// In particular, these transforms can be applied:
+    /// * Vector2(r, phi) == Vector2(-r, phi + 180_deg)
+    /// * Vector2(r, phi) == Vector2(r, phi + n * 360_deg)
+    ///
+    ////////////////////////////////////////////////////////////
+    Vector2(T r, Angle phi);
+    
     ////////////////////////////////////////////////////////////
     /// \brief Length of the vector <i><b>(floating-point)</b></i>.
     ///
@@ -103,7 +119,7 @@ public:
     /// 
     /// \return The smallest angle which rotates \c *this in positive
     /// or negative direction, until it has the same direction as \c rhs.
-    /// The result has a sign and lies in the range [-180, 180°).
+    /// The result has a sign and lies in the range [-180, 180) degrees.
     /// \pre Neither \c *this nor \c rhs is a zero vector.
     ///
     ////////////////////////////////////////////////////////////
@@ -114,7 +130,7 @@ public:
     /// 
     /// For example, the vector (1,0) corresponds to 0 degrees, (0,1) corresponds to 90 degrees.
     /// 
-    /// \return Angle in the range [-180°, 180°).
+    /// \return Angle in the range [-180, 180) degrees.
     /// \pre This vector is no zero vector.
     ///
     ////////////////////////////////////////////////////////////

include/SFML/System/Vector2.inl

@@ -53,6 +53,16 @@ y(static_cast<T>(vector.y))
 }
 
 
+////////////////////////////////////////////////////////////
+template <typename T>
+Vector2<T>::Vector2(T r, Angle phi) :
+x(r * static_cast<T>(std::cos(phi.asRadians()))),
+y(r * static_cast<T>(std::sin(phi.asRadians())))
+{
+    static_assert(std::is_floating_point_v<T>, "Vector2::Vector2(T, Angle) is only supported for floating point types");
+}
+
+
 ////////////////////////////////////////////////////////////
 template <typename T>
 T Vector2<T>::length() const

src/SFML/Graphics/CircleShape.cpp

@@ -73,11 +73,7 @@ std::size_t CircleShape::getPointCount() const
 Vector2f CircleShape::getPoint(std::size_t index) const
 {
     Angle angle = static_cast<float>(index) / static_cast<float>(m_pointCount) * sf::degrees(360) - sf::degrees(90);
-    float rad = angle.asRadians();
+    return Vector2f(m_radius, m_radius) + Vector2f(m_radius, angle);
-    float x = std::cos(rad) * m_radius;
-    float y = std::sin(rad) * m_radius;
-
-    return Vector2f(m_radius + x, m_radius + y);
 }
 
 } // namespace sf

test/System/Vector2.cpp

@@ -37,6 +37,57 @@ TEST_CASE("sf::Vector2 class template - [system]")
             CHECK(vector.x == static_cast<int>(sourceVector.x));
             CHECK(vector.y == static_cast<int>(sourceVector.y));
         }
+
+        SUBCASE("Length and angle constructor")
+        {
+            CHECK(sf::Vector2f(0, sf::degrees(0)) == sf::Vector2f(0, 0));
+            CHECK(sf::Vector2f(0, sf::degrees(45)) == sf::Vector2f(0, 0));
+            CHECK(sf::Vector2f(0, sf::degrees(90)) == sf::Vector2f(0, 0));
+            CHECK(sf::Vector2f(0, sf::degrees(135)) == sf::Vector2f(0, 0));
+            CHECK(sf::Vector2f(0, sf::degrees(180)) == sf::Vector2f(0, 0));
+            CHECK(sf::Vector2f(0, sf::degrees(270)) == sf::Vector2f(0, 0));
+            CHECK(sf::Vector2f(0, sf::degrees(360)) == sf::Vector2f(0, 0));
+            CHECK(sf::Vector2f(0, sf::degrees(-90)) == sf::Vector2f(0, 0));
+            CHECK(sf::Vector2f(0, sf::degrees(-180)) == sf::Vector2f(0, 0));
+            CHECK(sf::Vector2f(0, sf::degrees(-270)) == sf::Vector2f(0, 0));
+            CHECK(sf::Vector2f(0, sf::degrees(-360)) == sf::Vector2f(0, 0));
+
+            CHECK(sf::Vector2f(1, sf::degrees(0)) == sf::Vector2f(1, 0));
+            CHECK(sf::Vector2f(1, sf::degrees(45)) == ApproxVec2(std::sqrt(2.f) / 2.f, std::sqrt(2.f) / 2.f));
+            CHECK(sf::Vector2f(1, sf::degrees(90)) == ApproxVec2(0, 1));
+            CHECK(sf::Vector2f(1, sf::degrees(135)) == ApproxVec2(-std::sqrt(2.f) / 2.f, std::sqrt(2.f) / 2.f));
+            CHECK(sf::Vector2f(1, sf::degrees(180)) == ApproxVec2(-1, 0));
+            CHECK(sf::Vector2f(1, sf::degrees(270)) == ApproxVec2(0, -1));
+            CHECK(sf::Vector2f(1, sf::degrees(360)) == ApproxVec2(1, 0));
+            CHECK(sf::Vector2f(1, sf::degrees(-90)) == ApproxVec2(0, -1));
+            CHECK(sf::Vector2f(1, sf::degrees(-180)) == ApproxVec2(-1, 0));
+            CHECK(sf::Vector2f(1, sf::degrees(-270)) == ApproxVec2(0, 1));
+            CHECK(sf::Vector2f(1, sf::degrees(-360)) == ApproxVec2(1, 0));
+
+            CHECK(sf::Vector2f(-1, sf::degrees(0)) == sf::Vector2f(-1, 0));
+            CHECK(sf::Vector2f(-1, sf::degrees(45)) == ApproxVec2(-std::sqrt(2.f) / 2.f, -std::sqrt(2.f) / 2.f));
+            CHECK(sf::Vector2f(-1, sf::degrees(90)) == ApproxVec2(0, -1));
+            CHECK(sf::Vector2f(-1, sf::degrees(135)) == ApproxVec2(std::sqrt(2.f) / 2.f, -std::sqrt(2.f) / 2.f));
+            CHECK(sf::Vector2f(-1, sf::degrees(180)) == ApproxVec2(1, 0));
+            CHECK(sf::Vector2f(-1, sf::degrees(270)) == ApproxVec2(0, 1));
+            CHECK(sf::Vector2f(-1, sf::degrees(360)) == ApproxVec2(-1, 0));
+            CHECK(sf::Vector2f(-1, sf::degrees(-90)) == ApproxVec2(0, 1));
+            CHECK(sf::Vector2f(-1, sf::degrees(-180)) == ApproxVec2(1, 0));
+            CHECK(sf::Vector2f(-1, sf::degrees(-270)) == ApproxVec2(0, -1));
+            CHECK(sf::Vector2f(-1, sf::degrees(-360)) == ApproxVec2(-1, 0));
+
+            CHECK(sf::Vector2f(4.2f, sf::degrees(0)) == sf::Vector2f(4.2f, 0));
+            CHECK(sf::Vector2f(4.2f, sf::degrees(45)) == ApproxVec2(4.2f * std::sqrt(2.f) / 2.f, 4.2f * std::sqrt(2.f) / 2.f));
+            CHECK(sf::Vector2f(4.2f, sf::degrees(90)) == ApproxVec2(0, 4.2f));
+            CHECK(sf::Vector2f(4.2f, sf::degrees(135)) == ApproxVec2(-4.2f * std::sqrt(2.f) / 2.f, 4.2f * std::sqrt(2.f) / 2.f));
+            CHECK(sf::Vector2f(4.2f, sf::degrees(180)) == ApproxVec2(-4.2f, 0));
+            CHECK(sf::Vector2f(4.2f, sf::degrees(270)) == ApproxVec2(0, -4.2f));
+            CHECK(sf::Vector2f(4.2f, sf::degrees(360)) == ApproxVec2(4.2f, 0));
+            CHECK(sf::Vector2f(4.2f, sf::degrees(-90)) == ApproxVec2(0, -4.2f));
+            CHECK(sf::Vector2f(4.2f, sf::degrees(-180)) == ApproxVec2(-4.2f, 0));
+            CHECK(sf::Vector2f(4.2f, sf::degrees(-270)) == ApproxVec2(0, 4.2f));
+            CHECK(sf::Vector2f(4.2f, sf::degrees(-360)) == ApproxVec2(4.2f, 0));
+        }
     }
 
     SUBCASE("Unary operations")