Язык Си, помохите разобратся.
Вот код
Код:
// Geometric Tools, LLC
// Copyright (c) 1998-2010
// 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)
#include "Wm5MathematicsPCH.h"
#include "Wm5IntrCircle2Circle2.h"
namespace Wm5
{
//----------------------------------------------------------------------------
template <typename Real>
IntrCircle2Circle2<Real>::IntrCircle2Circle2 (const Circle2<Real>& circle0,
const Circle2<Real>& circle1)
:
mCircle0(&circle0),
mCircle1(&circle1)
{
}
//----------------------------------------------------------------------------
template <typename Real>
const Circle2<Real>& IntrCircle2Circle2<Real>::GetCircle0 () const
{
return *mCircle0;
}
//----------------------------------------------------------------------------
template <typename Real>
const Circle2<Real>& IntrCircle2Circle2<Real>::GetCircle1 () const
{
return *mCircle1;
}
//----------------------------------------------------------------------------
template <typename Real>
bool IntrCircle2Circle2<Real>::Find ()
{
// The two circles are |X-C0| = R0 and |X-C1| = R1. Define U = C1 - C0
// and V = Perp(U) where Perp(x,y) = (y,-x). Note that Dot(U,V) = 0 and
// |V|^2 = |U|^2. The intersection points X can be written in the form
// X = C0+s*U+t*V and X = C1+(s-1)*U+t*V. Squaring the circle equations
// and substituting these formulas into them yields
// R0^2 = (s^2 + t^2)*|U|^2
// R1^2 = ((s-1)^2 + t^2)*|U|^2.
// Subtracting and solving for s yields
// s = ((R0^2-R1^2)/|U|^2 + 1)/2
// Then replace in the first equation and solve for t^2
// t^2 = (R0^2/|U|^2) - s^2.
// In order for there to be solutions, the right-hand side must be
// nonnegative. Some algebra leads to the condition for existence of
// solutions,
// (|U|^2 - (R0+R1)^2)*(|U|^2 - (R0-R1)^2) <= 0.
// This reduces to
// |R0-R1| <= |U| <= |R0+R1|.
// If |U| = |R0-R1|, then the circles are side-by-side and just tangent.
// If |U| = |R0+R1|, then the circles are nested and just tangent.
// If |R0-R1| < |U| < |R0+R1|, then the two circles to intersect in two
// points.
Vector2<Real> U = mCircle1->Center - mCircle0->Center;
Real USqrLen = U.SquaredLength();
Real R0 = mCircle0->Radius, R1 = mCircle1->Radius;
Real R0mR1 = R0 - R1;
if (USqrLen < Math<Real>::ZERO_TOLERANCE
&& Math<Real>::FAbs(R0mR1) < Math<Real>::ZERO_TOLERANCE)
{
// Circles are essentially the same.
mIntersectionType = IT_OTHER;
mQuantity = 0;
return true;
}
Real R0mR1Sqr = R0mR1*R0mR1;
if (USqrLen < R0mR1Sqr)
{
mIntersectionType = IT_EMPTY;
mQuantity = 0;
return false;
}
Real R0pR1 = R0 + R1;
Real R0pR1Sqr = R0pR1*R0pR1;
if (USqrLen > R0pR1Sqr)
{
mIntersectionType = IT_EMPTY;
mQuantity = 0;
return false;
}
if (USqrLen < R0pR1Sqr)
{
if (R0mR1Sqr < USqrLen)
{
Real invUSqrLen = ((Real)1)/USqrLen;
Real s = ((Real)0.5)*((R0*R0-R1*R1)*invUSqrLen+(Real)1);
Vector2<Real> tmp = mCircle0->Center + s*U;
// In theory, discr is nonnegative. However, numerical round-off
// errors can make it slightly negative. Clamp it to zero.
Real discr = R0*R0*invUSqrLen - s*s;
if (discr < (Real)0)
{
discr = (Real)0;
}
Real t = Math<Real>::Sqrt(discr);
Vector2<Real> V(U.Y(), -U.X());
mQuantity = 2;
mPoint[0] = tmp - t*V;
mPoint[1] = tmp + t*V;
}
else
{
// |U| = |R0-R1|, circles are tangent.
mQuantity = 1;
mPoint[0] = mCircle0->Center + (R0/R0mR1)*U;
}
}
else
{
// |U| = |R0+R1|, circles are tangent.
mQuantity = 1;
mPoint[0] = mCircle0->Center + (R0/R0pR1)*U;
}
mIntersectionType = IT_POINT;
return true;
}
//----------------------------------------------------------------------------
template <typename Real>
int IntrCircle2Circle2<Real>::GetQuantity () const
{
return mQuantity;
}
//----------------------------------------------------------------------------
template <typename Real>
const Vector2<Real>& IntrCircle2Circle2<Real>::GetPoint (int i) const
{
return mPoint[i];
}
//----------------------------------------------------------------------------
template <typename Real>
const Circle2<Real>& IntrCircle2Circle2<Real>::GetIntersectionCircle () const
{
return *mCircle0;
}
//----------------------------------------------------------------------------
//----------------------------------------------------------------------------
// Explicit instantiation.
//----------------------------------------------------------------------------
template
class IntrCircle2Circle2<float>;
template
class IntrCircle2Circle2<double>;
//----------------------------------------------------------------------------
}
Код о пересечении 2-ух окружностей. Находит точки пересечения.
Помогите разобраться, если возможно и не сложно в блитце код напишите, тагды я сам 100 пудов разберусь. За язык Си садился только на 1 курсе в универе. |
