Пример #1
0
// From Graphics Gems - intersection of sphere with ray
void Foam::searchableSphere::findLineAll
(
    const point& start,
    const point& end,
    pointIndexHit& near,
    pointIndexHit& far
) const
{
    near.setMiss();
    far.setMiss();

    vector dir(end-start);
    scalar magSqrDir = magSqr(dir);

    if (magSqrDir > ROOTVSMALL)
    {
        const vector toCentre(centre_-start);
        scalar magSqrToCentre = magSqr(toCentre);

        dir /= Foam::sqrt(magSqrDir);

        scalar v = (toCentre & dir);

        scalar disc = sqr(radius_) - (magSqrToCentre - sqr(v));

        if (disc >= 0)
        {
            scalar d = Foam::sqrt(disc);

            scalar nearParam = v-d;

            if (nearParam >= 0 && sqr(nearParam) <= magSqrDir)
            {
                near.setHit();
                near.setPoint(start + nearParam*dir);
                near.setIndex(0);
            }

            scalar farParam = v+d;

            if (farParam >= 0 && sqr(farParam) <= magSqrDir)
            {
                far.setHit();
                far.setPoint(start + farParam*dir);
                far.setIndex(0);
            }
        }
    }
}
Пример #2
0
void Foam::planeSearchableSurface::findLineAll
(
    const point& start,
    const point& end,
    pointIndexHit& hit
) const
{
    hit.setMiss();

    vector dir=end-start;

    scalar f=plane_.normalIntersect(start,dir);
    if(0<=f && f<=1) {
        hit.rawPoint()=start+f*dir;
        hit.setHit();
        hit.setIndex(0);
    }
}
Пример #3
0
// From http://www.gamedev.net/community/forums/topic.asp?topic_id=467789 -
// intersection of cylinder with ray
void Foam::searchableCylinder::findLineAll
(
    const point& start,
    const point& end,
    pointIndexHit& near,
    pointIndexHit& far
) const
{
    near.setMiss();
    far.setMiss();

    vector point1Start(start-point1_);
    vector point2Start(start-point2_);
    vector point1End(end-point1_);

    // Quick rejection of complete vector outside endcaps
    scalar s1 = point1Start&unitDir_;
    scalar s2 = point1End&unitDir_;

    if ((s1 < 0 && s2 < 0) || (s1 > magDir_ && s2 > magDir_))
    {
        return;
    }

    // Line as P = start+t*V  where V is unit vector and t=[0..mag(end-start)]
    vector V(end-start);
    scalar magV = mag(V);
    if (magV < ROOTVSMALL)
    {
        return;
    }
    V /= magV;


    // We now get the nearest intersections to start. This can either be
    // the intersection with the end plane or with the cylinder side.

    // Get the two points (expressed in t) on the end planes. This is to
    // clip any cylinder intersection against.
    scalar tPoint1;
    scalar tPoint2;

    // Maintain the two intersections with the endcaps
    scalar tNear = VGREAT;
    scalar tFar = VGREAT;

    {
        scalar s = (V&unitDir_);
        if (mag(s) > VSMALL)
        {
            tPoint1 = -s1/s;
            tPoint2 = -(point2Start&unitDir_)/s;
            if (tPoint2 < tPoint1)
            {
                Swap(tPoint1, tPoint2);
            }
            if (tPoint1 > magV || tPoint2 < 0)
            {
                return;
            }

            // See if the points on the endcaps are actually inside the cylinder
            if (tPoint1 >= 0 && tPoint1 <= magV)
            {
                if (radius2(start+tPoint1*V) <= sqr(radius_))
                {
                    tNear = tPoint1;
                }
            }
            if (tPoint2 >= 0 && tPoint2 <= magV)
            {
                if (radius2(start+tPoint2*V) <= sqr(radius_))
                {
                    // Check if already have a near hit from point1
                    if (tNear <= 1)
                    {
                        tFar = tPoint2;
                    }
                    else
                    {
                        tNear = tPoint2;
                    }
                }
            }
        }
        else
        {
            // Vector perpendicular to cylinder. Check for outside already done
            // above so just set tpoint to allow all.
            tPoint1 = -VGREAT;
            tPoint2 = VGREAT;
        }
    }


    const vector x = point1Start ^ unitDir_;
    const vector y = V ^ unitDir_;
    const scalar d = sqr(radius_);

    // Second order equation of the form a*t^2 + b*t + c
    const scalar a = (y&y);
    const scalar b = 2*(x&y);
    const scalar c = (x&x)-d;

    const scalar disc = b*b-4*a*c;

    scalar t1 = -VGREAT;
    scalar t2 = VGREAT;

    if (disc < 0)
    {
        // Fully outside
        return;
    }
    else if (disc < ROOTVSMALL)
    {
        // Single solution
        if (mag(a) > ROOTVSMALL)
        {
            t1 = -b/(2*a);

            //Pout<< "single solution t:" << t1
            //    << " for start:" << start << " end:" << end
            //    << " c:" << c << endl;

            if (t1 >= 0 && t1 <= magV && t1 >= tPoint1 && t1 <= tPoint2)
            {
                // valid. Insert sorted.
                if (t1 < tNear)
                {
                    tFar = tNear;
                    tNear = t1;
                }
                else if (t1 < tFar)
                {
                    tFar = t1;
                }
            }
            else
            {
                return;
            }
        }
        else
        {
            // Aligned with axis. Check if outside radius
            //Pout<< "small discriminant:" << disc
            //    << " for start:" << start << " end:" << end
            //    << " magV:" << magV
            //    << " c:" << c << endl;
            if (c > 0)
            {
                return;
            }
        }
    }
    else
    {
        if (mag(a) > ROOTVSMALL)
        {
            scalar sqrtDisc = sqrt(disc);

            t1 = (-b - sqrtDisc)/(2*a);
            t2 = (-b + sqrtDisc)/(2*a);
            if (t2 < t1)
            {
                Swap(t1, t2);
            }

            if (t1 >= 0 && t1 <= magV && t1 >= tPoint1 && t1 <= tPoint2)
            {
                // valid. Insert sorted.
                if (t1 < tNear)
                {
                    tFar = tNear;
                    tNear = t1;
                }
                else if (t1 < tFar)
                {
                    tFar = t1;
                }
            }
            if (t2 >= 0 && t2 <= magV && t2 >= tPoint1 && t2 <= tPoint2)
            {
                // valid. Insert sorted.
                if (t2 < tNear)
                {
                    tFar = tNear;
                    tNear = t2;
                }
                else if (t2 < tFar)
                {
                    tFar = t2;
                }
            }
            //Pout<< "two solutions t1:" << t1 << " t2:" << t2
            //    << " for start:" << start << " end:" << end
            //    << " magV:" << magV
            //    << " c:" << c << endl;
        }
        else
        {
            // Aligned with axis. Check if outside radius
            //Pout<< "large discriminant:" << disc
            //    << " small a:" << a
            //    << " for start:" << start << " end:" << end
            //    << " magV:" << magV
            //    << " c:" << c << endl;
            if (c > 0)
            {
                return;
            }
        }
    }

    // Check tNear, tFar
    if (tNear >= 0 && tNear <= magV)
    {
        near.setPoint(start+tNear*V);
        near.setHit();
        near.setIndex(0);

        if (tFar <= magV)
        {
            far.setPoint(start+tFar*V);
            far.setHit();
            far.setIndex(0);
        }
    }
    else if (tFar >= 0 && tFar <= magV)
    {
        near.setPoint(start+tFar*V);
        near.setHit();
        near.setIndex(0);
    }
}