Add getter and setter for miter limit with simple tests

include/SFML/Graphics/Shape.hpp

@@ -127,6 +127,24 @@ class SFML_GRAPHICS_API Shape : public Drawable, public Transformable
     ////////////////////////////////////////////////////////////
     void setOutlineThickness(float thickness);
 
+    ////////////////////////////////////////////////////////////
+    /// \brief Set the limit on the ratio between miter length and outline thickness
+    ///
+    /// The edges of the shape's outline around sharp angles can meet
+    /// well beyond the outline thickness. When the ratio between the
+    /// miter length (distance between the outline's tip and the shape's
+    /// corner) and the outline thickness exceeds the given limit, then
+    /// the join is converted from a miter to a bevel.
+    /// The miter limit must be greater than or equal to 1.
+    /// By default, the miter limit is 4.
+    ///
+    /// \param miterLimit New miter limit
+    ///
+    /// \see getMiterLimit
+    ///
+    ////////////////////////////////////////////////////////////
+    void setMiterLimit(float miterLimit);
+
     ////////////////////////////////////////////////////////////
     /// \brief Get the source texture of the shape
     ///
@@ -181,6 +199,16 @@ class SFML_GRAPHICS_API Shape : public Drawable, public Transformable
     ////////////////////////////////////////////////////////////
     float getOutlineThickness() const;
 
+    ////////////////////////////////////////////////////////////
+    /// \brief Get the limit on the ratio between miter length and outline thickness
+    ///
+    /// \return Limit on the ratio between miter length and outline thickness
+    ///
+    /// \see setMiterLimit
+    ///
+    ////////////////////////////////////////////////////////////
+    float getMiterLimit() const;
+
     ////////////////////////////////////////////////////////////
     /// \brief Get the total number of points of the shape
     ///
@@ -314,6 +342,7 @@ class SFML_GRAPHICS_API Shape : public Drawable, public Transformable
     Color          m_fillColor{Color::White};    //!< Fill color
     Color          m_outlineColor{Color::White}; //!< Outline color
     float          m_outlineThickness{};         //!< Thickness of the shape's outline
+    float          m_miterLimit{4.f};            //!< Limit on the ratio between miter length and outline thickness
     VertexArray    m_vertices{PrimitiveType::TriangleFan};          //!< Vertex array containing the fill geometry
     VertexArray    m_outlineVertices{PrimitiveType::TriangleStrip}; //!< Vertex array containing the outline geometry
     FloatRect      m_insideBounds;                                  //!< Bounding rectangle of the inside (fill)

src/SFML/Graphics/Shape.cpp

@@ -31,6 +31,7 @@
 
 #include <algorithm>
 
+#include <cassert>
 #include <cmath>
 
 namespace
@@ -123,7 +124,7 @@ const Color& Shape::getOutlineColor() const
 void Shape::setOutlineThickness(float thickness)
 {
     m_outlineThickness = thickness;
-    update(); // recompute everything because the whole shape must be offset
+    updateOutline();
 }
 
 
@@ -134,6 +135,22 @@ float Shape::getOutlineThickness() const
 }
 
 
+////////////////////////////////////////////////////////////
+void Shape::setMiterLimit(float miterLimit)
+{
+    assert(1.f <= miterLimit && "Miter limit must be greater than or equal to 1");
+    m_miterLimit = miterLimit;
+    updateOutline();
+}
+
+
+////////////////////////////////////////////////////////////
+float Shape::getMiterLimit() const
+{
+    return m_miterLimit;
+}
+
+
 ////////////////////////////////////////////////////////////
 Vector2f Shape::getGeometricCenter() const
 {
@@ -290,8 +307,8 @@ void Shape::updateTexCoords()
 ////////////////////////////////////////////////////////////
 void Shape::updateOutline()
 {
-    // Return if there is no outline
-    if (m_outlineThickness == 0.f)
+    // Return if there is no outline or no vertices
+    if (m_outlineThickness == 0.f || m_vertices.getVertexCount() < 2)
     {
         m_outlineVertices.clear();
         m_bounds = m_insideBounds;
@@ -303,9 +320,8 @@ void Shape::updateOutline()
                                                // We will add two more vertices each time we need a bevel.
 
     // Parameters to compute bevels
-    const float miterLimit   = 4.f;
     const float minExtension = 1.f;
-    const float maxExtension = std::sqrt(miterLimit * miterLimit - 1.f);
+    const float maxExtension = std::sqrt(m_miterLimit * m_miterLimit - 1.f);
 
     // Determine if points are defined clockwise or counterclockwise. This will impact normals computation.
     const bool flipNormals = [this, count]()
@@ -333,7 +349,7 @@ void Shape::updateOutline()
 
         // Decide whether to add a bevel or not
         const float factor             = 1.f + n1.dot(n2);
-        const float squaredLengthRatio = miterLimit * miterLimit * factor / 2.f;
+        const float squaredLengthRatio = m_miterLimit * m_miterLimit * factor / 2.f;
         const bool  isConvexCorner     = 0.f <= d1.dot(n2) * m_outlineThickness;
         const bool  needsBevel         = factor == 0.f || (squaredLengthRatio < 1.f && isConvexCorner);
 

test/Graphics/Shape.test.cpp

@@ -56,6 +56,7 @@ TEST_CASE("[Graphics] sf::Shape")
         CHECK(triangleShape.getFillColor() == sf::Color::White);
         CHECK(triangleShape.getOutlineColor() == sf::Color::White);
         CHECK(triangleShape.getOutlineThickness() == 0.0f);
+        CHECK(triangleShape.getMiterLimit() == 4.0f);
         CHECK(triangleShape.getLocalBounds() == sf::FloatRect());
         CHECK(triangleShape.getGlobalBounds() == sf::FloatRect());
     }
@@ -88,6 +89,13 @@ TEST_CASE("[Graphics] sf::Shape")
         CHECK(triangleShape.getOutlineThickness() == 3.14f);
     }
 
+    SECTION("Set/get miter limit")
+    {
+        TriangleShape triangleShape({});
+        triangleShape.setMiterLimit(6.28f);
+        CHECK(triangleShape.getMiterLimit() == 6.28f);
+    }
+
     SECTION("Virtual functions: getPoint, getPointCount, getGeometricCenter")
     {
         const TriangleShape triangleShape({2, 2});