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Fixed: outline direction were depending on the order in which points were defined in a Shape

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This commit is contained in:
Laurent Gomila 2013-02-23 15:55:47 +01:00
parent a40ef79a18
commit b85bf692c0
1 changed files with 14 additions and 1 deletions
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15
src/SFML/Graphics/Shape.cpp
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@ -43,6 +43,12 @@ namespace
normal /= length; normal /= length;
return normal; 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 n1 = computeNormal(p0, p1);
Vector2f n2 = computeNormal(p1, p2); 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 // Combine them to get the extrusion direction
float factor = 1.f + (n1.x * n2.x + n1.y * n2.y); 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 // Update the outline points
m_outlineVertices[i * 2 + 0].position = p1; m_outlineVertices[i * 2 + 0].position = p1;