IceRay.cpp

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/*
        O = Origin = impact point
        i = normalized vector along the x axis
        j = normalized vector along the y axis = actually the normal vector in O
        D = Direction vector, norm |D| = 1
        N = Projection of D on y axis, norm |N| = normal reaction
        T = Projection of D on x axis, norm |T| = tangential reaction
        R = Reflexion vector
 
              ^y
              |
              |
              |
       _  _  _| _ _ _
       *      *      *|
        \     |     /
         \    |N   /  |
         R\   |   /D
           \  |  /    |
            \ | /
    _________\|/______*_______>x
               O    T
 
        Let define theta = angle between D and N. Then cos(theta) = |N| / |D| = |N| since D is normalized.
 
        j|D = |j|*|D|*cos(theta) => |N| = j|D
 
        Then we simply have:
 
        D = N + T
 
        To compute tangential reaction :
 
        T = D - N
 
        To compute reflexion vector :
 
        R = N - T = N - (D-N) = 2*N - D
*/
 
// Precompiled Header
#include "Stdafx.h"
 
using namespace IceMaths;
 
float Ray::SquareDistance(const Point& point, float* t) const
{
        Point Diff = point - mOrig;
        float fT = Diff | mDir;
 
        if(fT<=0.0f)
        {
                fT = 0.0f;
        }
        else
        {
                fT /= mDir.SquareMagnitude();
                Diff -= fT*mDir;
        }
 
        if(t) *t = fT;
 
        return Diff.SquareMagnitude();
}