diff --git a/src/SFML/Graphics/Shape.cpp b/src/SFML/Graphics/Shape.cpp index 8f674da0..51be2ec8 100644 --- a/src/SFML/Graphics/Shape.cpp +++ b/src/SFML/Graphics/Shape.cpp @@ -43,6 +43,12 @@ namespace normal /= length; return normal; } + + // Compute the dot product of two vectors + float dotProduct(const sf::Vector2f& p1, const sf::Vector2f& p2) + { + return p1.x * p2.x + p1.y * p2.y; + } } @@ -258,9 +264,16 @@ void Shape::updateOutline() Vector2f n1 = computeNormal(p0, p1); Vector2f n2 = computeNormal(p1, p2); + // Make sure that the normals point towards the outside of the shape + // (this depends on the order in which the points were defined) + if (dotProduct(n1, m_vertices[0].position - p1) > 0) + n1 = -n1; + if (dotProduct(n2, m_vertices[0].position - p1) > 0) + n2 = -n2; + // Combine them to get the extrusion direction float factor = 1.f + (n1.x * n2.x + n1.y * n2.y); - Vector2f normal = -(n1 + n2) / factor; + Vector2f normal = (n1 + n2) / factor; // Update the outline points m_outlineVertices[i * 2 + 0].position = p1;