void ValidatePolygon()
{
HideError();
if (PolyData.Vertices.Count <= 1 || PolyData.Vertices.Count > Box2DSettings.b2_maxPolygonVertices)
{
ShowError("Polygon vertice count", "Polygons can only contain between 2 and 8 vertices.\nNote that a polygon of 2 vertices is called an edge (Box2D 2.1.2).");
}
else if (PolyData.Vertices.Count > 2)
{
// Compute normals. Ensure the edges have non-zero length.
for (int i = 0; i < PolyData.Vertices.Count; ++i)
{
int i1 = i;
int i2 = i + 1 < PolyData.Vertices.Count ? i + 1 : 0;
Vec2 edge = PolyData.Vertices[i2] - PolyData.Vertices[i1];
if (!(edge.LengthSquared() > float.Epsilon * float.Epsilon))
{
ShowError("Edge length", "An edge has an incredibly small length. This may be due\nto vertices too close together.");
return;
}
}
for (int i = 0; i < PolyData.Vertices.Count; ++i)
{
int i1 = i;
int i2 = i + 1 < PolyData.Vertices.Count ? i + 1 : 0;
Vec2 edge = PolyData.Vertices[i2] - PolyData.Vertices[i1];
for (int j = 0; j < PolyData.Vertices.Count; ++j)
{
// Don't check vertices on the current edge.
if (j == i1 || j == i2)
{
continue;
}
Vec2 r = PolyData.Vertices[j] - PolyData.Vertices[i1];
// Your polygon is non-convex (it has an indentation) or
// has colinear edges.
float s = edge.Cross(r);
if (!(s > 0.0f))
{
ShowError("Non-convex/Collinear", "Your polygon is non-convex or has collinear edges.\nTry using the \"Reverse\" button; if that doesn't work,\nthe problem lies within the spacing of your vertices.");
return;
}
}
}
Vec2 centroid;
try
{
PolygonShape.ComputeCentroid(out centroid, PolyData.Vertices);
}
catch
{
ShowError("Polygon area", "The area of your polygon is incredibly small.");
}
}
}