source: GTP/trunk/Lib/Illum/IBRBillboardCloudTrees/OGRE/include/BBC/BBCUtil.h @ 778

#ifndef _BBCUTIL_H
#define _BBCUTIL_H

#include <BBCPrerequisites.h>

namespace BBC {

const Ogre::Real EPSILON_INTERSECT = 0.00000001;

class _BBCExport Util
{
public:
        static Ogre::String getBaseName(Ogre::String fileName)
        {
                Ogre::String baseName;
                size_t pos = fileName.find_last_of(".");
                baseName = fileName.substr(0, pos);
                return baseName;
        }

        static Ogre::String getExtensionName(Ogre::String fileName)
        {
                Ogre::String ext;
                size_t pos = fileName.find_last_of(".");
                ext = fileName.substr(pos+1);
                return ext;
        }

        static unsigned int nextPowerOf2(unsigned int nPlanes)
        {
                unsigned int depth = 1;
                while (depth < nPlanes)
                {
                        depth = depth << 1;
                }
                return depth;
        }

        // Calculate the line segment PaPb that is the shortest route between
        // two lines P1P2 and P3P4. Calculate also the values of mua and mub where
        //   Pa = P1 + mua (P2 - P1)
        //       Pb = P3 + mub (P4 - P3)
        // Return false if no solution exists.

        static int lineLineIntersect(
                Ogre::Vector3 p1, Ogre::Vector3 p2, Ogre::Vector3 p3, Ogre::Vector3 p4, Ogre::Vector3 *pa, Ogre::Vector3 *pb,
                Ogre::Real *mua, Ogre::Real *mub)
        {
                Ogre::Vector3 p13,p43,p21;
                Ogre::Real d1343,d4321,d1321,d4343,d2121;
                Ogre::Real numer,denom;

                p13.x = p1.x - p3.x;
                p13.y = p1.y - p3.y;
                p13.z = p1.z - p3.z;
                p43.x = p4.x - p3.x;
                p43.y = p4.y - p3.y;
                p43.z = p4.z - p3.z;
                if (Ogre::Math::Abs(p43.x)  < EPSILON_INTERSECT && Ogre::Math::Abs(p43.y)  < EPSILON_INTERSECT && Ogre::Math::Abs(p43.z)  < EPSILON_INTERSECT)
                {
                        return(false);
                }
                p21.x = p2.x - p1.x;
                p21.y = p2.y - p1.y;
                p21.z = p2.z - p1.z;
                if (Ogre::Math::Abs(p21.x)  < EPSILON_INTERSECT && Ogre::Math::Abs(p21.y)  < EPSILON_INTERSECT && Ogre::Math::Abs(p21.z)  < EPSILON_INTERSECT)
                {
                        return(false);
                }

                d1343 = p13.x * p43.x + p13.y * p43.y + p13.z * p43.z;
                d4321 = p43.x * p21.x + p43.y * p21.y + p43.z * p21.z;
                d1321 = p13.x * p21.x + p13.y * p21.y + p13.z * p21.z;
                d4343 = p43.x * p43.x + p43.y * p43.y + p43.z * p43.z;
                d2121 = p21.x * p21.x + p21.y * p21.y + p21.z * p21.z;

                denom = d2121 * d4343 - d4321 * d4321;
                if (Ogre::Math::Abs(denom) < EPSILON_INTERSECT)
                {
                        return(false);
                }
                numer = d1343 * d4321 - d1321 * d4343;

                *mua = numer / denom;
                *mub = (d1343 + d4321 * (*mua)) / d4343;

                pa->x = p1.x + *mua * p21.x;
                pa->y = p1.y + *mua * p21.y;
                pa->z = p1.z + *mua * p21.z;
                pb->x = p3.x + *mub * p43.x;
                pb->y = p3.y + *mub * p43.y;
                pb->z = p3.z + *mub * p43.z;

                return(true);
        }
};

/*
extern "C" _BBCExport Ogre::Real fround(Ogre::Real n, unsigned d)
{ 
        return floor(n * pow((Ogre::Real)10.,(int) d) + .5) / pow((Ogre::Real)10.,(int) d);
}

extern "C" _BBCExport int iround(Ogre::Real x)
{
      return (int)floor(x + 0.5);
}
*/
}

#endif