libwildmagic-dev 5.13-1ubuntu3 / usr / include / libwildmagic / Wm5ConvexPolygon2.inl

// Geometric Tools, LLC
// Copyright (c) 1998-2014
// Distributed under the Boost Software License, Version 1.0.
// http://www.boost.org/LICENSE_1_0.txt
// http://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
//
// File Version: 5.0.0 (2010/01/01)

//----------------------------------------------------------------------------
template <typename Real>
ConvexPolygon2<Real>::ConvexPolygon2 (int numVertices,
    Vector2<Real>* vertices, NCLine* lines)
    :
    Polygon2<Real>(numVertices, vertices)
{
    if (lines)
    {
        mLines = lines;
    }
    else
    {
        mLines = new1<NCLine>(mNumVertices);
        UpdateLines();
    }
}
//----------------------------------------------------------------------------
template <typename Real>
ConvexPolygon2<Real>::ConvexPolygon2 (const ConvexPolygon2& polygon)
    :
    Polygon2<Real>(polygon)
{
    mLines = 0;
    *this = polygon;
}
//----------------------------------------------------------------------------
template <typename Real>
ConvexPolygon2<Real>::~ConvexPolygon2 ()
{
}
//----------------------------------------------------------------------------
template <typename Real>
ConvexPolygon2<Real>& ConvexPolygon2<Real>::operator= (
    const ConvexPolygon2& polygon)
{
    Polygon2<Real>::operator=(polygon);
    mLines = polygon.mLines;
    mSharingEdges = polygon.mSharingEdges;
    return *this;
}
//----------------------------------------------------------------------------
template <typename Real>
const typename ConvexPolygon2<Real>::NCLine*
ConvexPolygon2<Real>::GetLines () const
{
    return mLines;
}
//----------------------------------------------------------------------------
template <typename Real>
const typename ConvexPolygon2<Real>::NCLine&
ConvexPolygon2<Real>::GetLine (int i) const
{
    assertion(0 <= i && i < mNumVertices, "Invalid index in GetLine\n");
    return mLines[i];
}
//----------------------------------------------------------------------------
template <typename Real>
void ConvexPolygon2<Real>::SetVertex (int i, const Vector2<Real>& vertex)
{
    Polygon2<Real>::SetVertex(i, vertex);

    // Keep track of edges sharing this vertex.  Their lines need to be
    // updated later.  The edges associated with vertex index i are
    // E[i] = <V[i],V[i+1]> and E[i-1] = <V[i-1],V[i]>, where i+1 and i-1
    // are computed modulo the number of vertices.
    mSharingEdges.insert((i - 1) % mNumVertices);
    mSharingEdges.insert(i);
}
//----------------------------------------------------------------------------
template <typename Real>
void ConvexPolygon2<Real>::UpdateLines ()
{
    if (mSharingEdges.size() > 0)
    {
        Vector2<Real> average = ComputeVertexAverage();
        for (int i = 0; i < mNumVertices; ++i)
        {
            UpdateLine(i, average);
        }
    }
}
//----------------------------------------------------------------------------
template <typename Real>
bool ConvexPolygon2<Real>::IsConvex (Real threshold) const
{
    Real maxDistance = -Math<Real>::MAX_REAL;
    Real minDistance = Math<Real>::MAX_REAL;

    for (int j = 0; j < mNumVertices; ++j)
    {
        const NCLine& line = mLines[j];
        for (int i = 0; i < mNumVertices; ++i)
        {
            Real distance = line.first.Dot(mVertices[i]) - line.second;
            if (distance < minDistance)
            {
                minDistance = distance;
            }
            if (distance > maxDistance)
            {
                maxDistance = distance;
            }
            if (distance < threshold)
            {
                return false;
            }
        }
    }

    return true;
}
//----------------------------------------------------------------------------
template <typename Real>
bool ConvexPolygon2<Real>::Contains (const Vector2<Real>& p,
    Real threshold) const
{
    for (int i = 0; i < mNumVertices; ++i)
    {
        const NCLine& line = mLines[i];
        Real distance = line.first.Dot(p) - line.second;
        if (distance < threshold)
        {
            return false;
        }
    }
    return true;
}
//----------------------------------------------------------------------------
template <typename Real>
void ConvexPolygon2<Real>::UpdateLine (int i, const Vector2<Real>& average)
{
    Vector2<Real>& vertex0 = mVertices[i];
    Vector2<Real>& vertex1 = mVertices[(i + 1) % mNumVertices];

    Vector2<Real> diff = average - vertex0;
    Vector2<Real> edge = vertex1 - vertex0;
    Vector2<Real> normal = -edge.Perp();
    Real length = normal.Length();
    if (length > Math<Real>::ZERO_TOLERANCE)
    {
        normal /= length;
        Real dot = normal.Dot(diff);
        assertion(dot >= (Real)0, "Dot product must be nonnegative\n");
        if (dot < (Real)0)
        {
            normal = -normal;
        }
    }
    else
    {
        // The edge is degenerate.  Use a "normal" that points towards
        // the average.
        normal = diff;
        normal.Normalize();
    }

    // This line has an inner-pointing normal.
    mLines[i].first = normal;
    mLines[i].second = normal.Dot(vertex0);
}
//----------------------------------------------------------------------------