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////////////////////////////////////////////////////////////////////////////////////////////////////

#include "frustum.h"

Frustum::Frustum()

{

    // EMPTY!

}

void

Frustum::update(

    const Camera &rkCamera)

{

    float16 kClipSpace = rkCamera.getModelViewProjectionMatrix();

    float4 kC0 = kClipSpace.getColumn(0);

    float4 kC1 = kClipSpace.getColumn(1);

    float4 kC2 = kClipSpace.getColumn(2);

    float4 kC3 = kClipSpace.getColumn(3);

    m_akPlanes[RIGHT ] = kC3 - kC0;

    m_akPlanes[LEFT  ] = kC3 + kC0;

    m_akPlanes[TOP   ] = kC3 - kC1;

    m_akPlanes[BOTTOM] = kC3 + kC1;

    m_akPlanes[BACK  ] = kC3 - kC2;

    m_akPlanes[FRONT ] = kC3 + kC2;

/*

    float4 *pkPlane = &m_akPlanes[RIGHT];

    pkPlane->x = kClipSpace[0][3] - kClipSpace[0][0];

    pkPlane->y = kClipSpace[1][3] - kClipSpace[1][0];

    pkPlane->z = kClipSpace[2][3] - kClipSpace[2][0];

    pkPlane->w = kClipSpace[3][3] - kClipSpace[3][0];

    pkPlane = &m_akPlanes[LEFT];

    pkPlane->x = kClipSpace[0][3] + kClipSpace[0][0];

    pkPlane->y = kClipSpace[1][3] + kClipSpace[1][0];

    pkPlane->z = kClipSpace[2][3] + kClipSpace[2][0];

    pkPlane->w = kClipSpace[3][3] + kClipSpace[3][0];

    pkPlane = &m_akPlanes[BOTTOM];

    pkPlane->x = kClipSpace[0][3] + kClipSpace[0][1];

    pkPlane->y = kClipSpace[1][3] + kClipSpace[1][1];

    pkPlane->z = kClipSpace[2][3] + kClipSpace[2][1];

    pkPlane->w = kClipSpace[3][3] + kClipSpace[3][1];

    pkPlane = &m_akPlanes[TOP];

    pkPlane->x = kClipSpace[0][3] - kClipSpace[0][1];

    pkPlane->y = kClipSpace[1][3] - kClipSpace[1][1];

    pkPlane->z = kClipSpace[2][3] - kClipSpace[2][1];

    pkPlane->w = kClipSpace[3][3] - kClipSpace[3][1];

    pkPlane = &m_akPlanes[BACK];

    pkPlane->x = kClipSpace[0][3] - kClipSpace[0][2];

    pkPlane->y = kClipSpace[1][3] - kClipSpace[1][2];

    pkPlane->z = kClipSpace[2][3] - kClipSpace[2][2];

    pkPlane->w = kClipSpace[3][3] - kClipSpace[3][2];

    pkPlane = &m_akPlanes[FRONT];

    pkPlane->x = kClipSpace[0][3] + kClipSpace[0][2];

    pkPlane->y = kClipSpace[1][3] + kClipSpace[1][2];

    pkPlane->z = kClipSpace[2][3] + kClipSpace[2][2];

    pkPlane->w = kClipSpace[3][3] + kClipSpace[3][2];

*/

    for(uint i = 0; i < 6; i++)

    { 

        float fD = sqrtf(m_akPlanes[i].x * m_akPlanes[i].x +

                         m_akPlanes[i].y * m_akPlanes[i].y + 

                         m_akPlanes[i].z * m_akPlanes[i].z );

        if(fD > 0.0f)

            m_akPlanes[i] /= fD;

    }

}

bool

Frustum::isSphereVisible(

    const float3 &rkCenter,

    float fRadius) const

{

    for(uint i = 0; i < 6; i++ )    

    {

        float fD = m_akPlanes[i].x * rkCenter.x + 

                   m_akPlanes[i].y * rkCenter.y + 

                   m_akPlanes[i].z * rkCenter.z + 

                   m_akPlanes[i].w;

        if( fD <= -fRadius )

        {

            return false;

        }

    }

    return true;

}