exact_predicates_gmp.h

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#pragma once
#include "vde/foundation/exact_predicates.h"
 
#ifdef VDE_USE_GMP
#include <gmpxx.h>
 
namespace vde::foundation::exact {
 
struct GmpExact {
    using Rational = mpq_class;
 
    static Orientation orient_2d(const Point2D& a, const Point2D& b, const Point2D& c) {
        Rational ax(a.x()), ay(a.y());
        Rational bx(b.x()), by(b.y());
        Rational cx(c.x()), cy(c.y());
        Rational det = (bx - ax) * (cy - ay) - (by - ay) * (cx - ax);
        int s = mpq_sgn(det.get_mpq_t());
        return s > 0 ? Orientation::CounterClockwise :
               s < 0 ? Orientation::Clockwise : Orientation::Collinear;
    }
 
    static Orientation orient_3d(const Point3D& a, const Point3D& b,
                                  const Point3D& c, const Point3D& d) {
        Rational ax(a.x()), ay(a.y()), az(a.z());
        Rational bx(b.x()), by(b.y()), bz(b.z());
        Rational cx(c.x()), cy(c.y()), cz(c.z());
        Rational dx(d.x()), dy(d.y()), dz(d.z());
 
        Rational adx = ax - dx, ady = ay - dy, adz = az - dz;
        Rational bdx = bx - dx, bdy = by - dy, bdz = bz - dz;
        Rational cdx = cx - dx, cdy = cy - dy, cdz = cz - dz;
 
        Rational det = adx * (bdy * cdz - bdz * cdy)
                     + bdx * (cdy * adz - cdz * ady)
                     + cdx * (ady * bdz - adz * bdy);
 
        int s = mpq_sgn(det.get_mpq_t());
        return s > 0 ? Orientation::CounterClockwise :
               s < 0 ? Orientation::Clockwise : Orientation::Collinear;
    }
 
    static CircleTest in_circle(const Point2D& a, const Point2D& b,
                                const Point2D& c, const Point2D& d) {
        Rational ax(a.x()), ay(a.y());
        Rational bx(b.x()), by(b.y());
        Rational cx(c.x()), cy(c.y());
        Rational dx(d.x()), dy(d.y());
 
        Rational adx = ax - dx, ady = ay - dy;
        Rational bdx = bx - dx, bdy = by - dy;
        Rational cdx = cx - dx, cdy = cy - dy;
 
        Rational ab = adx * bdy - ady * bdx;
        Rational bc = bdx * cdy - bdy * cdx;
        Rational ca = cdx * ady - cdy * adx;
        Rational al = adx * adx + ady * ady;
        Rational bl = bdx * bdx + bdy * bdy;
        Rational cl = cdx * cdx + cdy * cdy;
 
        Rational det = al * bc + bl * ca + cl * ab;
        int s = mpq_sgn(det.get_mpq_t());
        return s > 0 ? CircleTest::Inside :
               s < 0 ? CircleTest::Outside : CircleTest::On;
    }
};
 
}  // namespace vde::foundation::exact
 
#endif // VDE_USE_GMP