// tests if two extents overlapbool ExtentsOverlap(float min0, float max0, float min1, float max1){    return !(min0 > max1 || min1 > max0);}// compute the extents of one box agaisnt one vectorvoid ComputeBoxExtents(Vector Axis, OBBox Box, float& min, float &max){    float p = Box.Position.Dot(Axis);    float r0 = fabs(Box.Dir[0],Dot(Axis)) * Box.HalfSize.x;    float r1 = fabs(Box.Dir[1],Dot(Axis)) * Box.HalfSize.y;    float r2 = fabs(Box.Dir[2],Dot(Axis)) * Box.HalfSize.z;    float r = r0+r1+r2;    min = p-r;    max = p+r;}bool AxisOverlap(Vector Axis, OBBox Box0, OBBox Box1){    float min0, max0;    float min1, max1;    ComputeBoxExtents(Axis, Box0, min0, max0);    ComputeBoxExtents(Axis, Box1, min1, max1);        return ExtentsOverlap(min0, max0, min1, max1);}bool BoxBoxIntersect(OBBox Box0, OBBox Box1){    if (!AxisOverlap(Box0.Dir[0], Box0, Box1)) return false;    if (!AxisOverlap(Box0.Dir[1], Box0, Box1)) return false;    if (!AxisOverlap(Box0.Dir[2], Box0, Box1)) return false;        if (!AxisOverlap(Box1.Dir[0], Box0, Box1)) return false;    if (!AxisOverlap(Box1.Dir[1], Box0, Box1)) return false;    if (!AxisOverlap(Box1.Dir[2], Box0, Box1)) return false;        if (!AxisOverlap(Box0.Dir[0].Cross(Box1.Dir[0]), Box0, Box1)) return false;    if (!AxisOverlap(Box0.Dir[0].Cross(Box1.Dir[1]), Box0, Box1)) return false;    if (!AxisOverlap(Box0.Dir[0].Cross(Box1.Dir[2]), Box0, Box1)) return false;    if (!AxisOverlap(Box0.Dir[1].Cross(Box1.Dir[0]), Box0, Box1)) return false;    if (!AxisOverlap(Box0.Dir[1].Cross(Box1.Dir[1]), Box0, Box1)) return false;    if (!AxisOverlap(Box0.Dir[1].Cross(Box1.Dir[2]), Box0, Box1)) return false;    if (!AxisOverlap(Box0.Dir[2].Cross(Box1.Dir[0]), Box0, Box1)) return false;    if (!AxisOverlap(Box0.Dir[2].Cross(Box1.Dir[1]), Box0, Box1)) return false;    if (!AxisOverlap(Box0.Dir[2].Cross(Box1.Dir[2]), Box0, Box1)) return false;    return true;}

bool AxisOverlap(Vector Axis, OBBox Box0, OBBox Box1, float& min0, float& max0, float& min1, float& max1){    ComputeBoxExtents(Axis, Box0, min0, max0);    ComputeBoxExtents(Axis, Box1, min1, max1);        return ExtentsOverlap(min0, max0, min1, max1);}bool BoxBoxIntersect(OBBox Box0, OBBox Box1, Vector& Ncoll, float& dcoll){    Vector Axis[15];    float min0[15], max0[15], min1[15], max1[15];    Axis[0] = Box0.Dir[0]; if (!AxisOverlap(Axis[0], Box0, Box1, min0[0], max0[0], min1[0], max1[0])) return false;    Axis[1] = Box0.Dir[1]; if (!AxisOverlap(Axis[1], Box0, Box1, min0[1], max0[1], min1[1], max1[1])) return false;    Axis[2] = Box0.Dir[2]; if (!AxisOverlap(Axis[2], Box0, Box1, min0[2], max0[2], min1[2], max1[2])) return false;    ///.......    /// ect for the other 12 axes....        /// calculate the best candidate for a separation axis    if (!FindSeparationAxis(Axis, min0, max0, min1, max1, 15, Ncoll, dcoll)) return false;    /// make sure the normal is pointing the right way    /// the normal should point towards box0    Vector D = Box1.Position - Box0.Position;    if (D * Ncoll < 0.0f)        Ncoll *= -1.0f;        return true;}bool FindSeparationAxis(Vector *Axis, float* min0, float* max0, float* min1, float* max1, int NumAxes, Vector& Ncoll, float& dcoll){    float dmin;    float iminaxis = -1;    for(int i = 0; i < NumAxes; i ++)    {        // compute theintersection of the two extents on that axis        float min = (min0[i] > min1[i])? min0[i] : min1[i];        float max = (max0[i] < max1[i])> max1[i] : max0[i];          float d = max - min; // intersection amount        // extents not intersecting? surely this is wrong        if (d < 0.0f)             Assert("Error. Box should not be separated at this stage.");        float axis_length = Axis[i].Length();        // degenerate axis? then skip the axis        if (axis_length < 0.000000001f)            continue;        // normalise the overlap amount on that axis, so we can compare them        d /= axis_length;        // this is the separation axis with minimum depth found so far        if (d < dmin)        {             dmin  = d;             Ncoll = Axis[i] / axis_length; // normalise normal             dcoll = d;             iminaxis = i; // signal we found a solution        }    }    // we failed to find a separation axis. probably because one of the box is completely degenerate (size or axes of the box are garbage)    if (iminaxis == -1)        Assert("Failed to find a separation axis.");    return true;}