BoundingCone::BoundingCone(const BoundingBox& box, const D3DXMATRIX& projection, const D3DXVECTOR3& apex)
{
const D3DXVECTOR3 yAxis(0.f, 1.f, 0.f);
const D3DXVECTOR3 zAxis(0.f, 0.f, 1.f);
const D3DXVECTOR3 negZAxis(0.f, 0.f, -1.f);
// compute a tight bounding sphere for the vertices of the bounding boxes.
// the vector from the apex to the center of the sphere is the optimized view direction
// start by xforming all points to post-projective space
D3DXVECTOR3 ppPts[ box.CornerCount ];
box.GetCorners( ppPts );
for( int index=0; index<box.CornerCount; index++)
{
D3DXVec3TransformCoord( &ppPts[index], &ppPts[index], &projection );
}
// get minimum bounding sphere
BoundingSphere bSphere = BoundingSphere::CreateFromPoints( ppPts,box.CornerCount );
float min_cosTheta = 1.f;
m_direction = bSphere.GetCenter() - apex;
D3DXVec3Normalize(&m_direction, &m_direction);
D3DXVECTOR3 axis = yAxis;
if( fabsf(D3DXVec3Dot(&yAxis, &m_direction)) > 0.99f )
{
axis = zAxis;
}
D3DXMatrixLookAtLH(&m_lookAt, &apex, &(apex+m_direction), &axis);
m_near = 1e32f;
m_far = 0.f;
float maxx=0.f, maxy=0.f;
for( int index=0; index<box.CornerCount; index++ )
{
D3DXVECTOR3 tmp;
D3DXVec3TransformCoord(&tmp, &ppPts[index], &m_lookAt);
maxx = max(maxx, fabsf(tmp.x / tmp.z));
maxy = max(maxy, fabsf(tmp.y / tmp.z));
m_near = min(m_near, tmp.z);
m_far = max(m_far, tmp.z);
}
m_fovx = atanf(maxx);
m_fovy = atanf(maxy);
}
BoundingCone::BoundingCone(const BoundingBox& box, const D3DXMATRIX& projection, const D3DXVECTOR3& apex, const D3DXVECTOR3& direction )
{
m_direction = direction;
const D3DXVECTOR3 yAxis(0.f, 1.f, 0.f);
const D3DXVECTOR3 zAxis(0.f, 0.f, 1.f);
D3DXVec3Normalize(&m_direction, &m_direction);
D3DXVECTOR3 axis = yAxis;
if ( fabsf(D3DXVec3Dot(&yAxis, &m_direction))>0.99f )
{
axis = zAxis;
}
D3DXMatrixLookAtLH( &m_lookAt, &apex, &(apex+m_direction), &axis );
float maxx = 0.f, maxy = 0.f;
m_near = 1e32f;
m_far = 0.f;
D3DXMATRIX concatMatrix;
D3DXMatrixMultiply( &concatMatrix, &projection, &m_lookAt );
D3DXVECTOR3 ppPts[ box.CornerCount ];
box.GetCorners( ppPts );
for(int index=0; index<box.CornerCount; index++)
{
D3DXVECTOR3 vec = ppPts[index];
D3DXVec3TransformCoord(&vec, &vec, &concatMatrix);
maxx = max(maxx, fabsf(vec.x / vec.z));
maxy = max(maxy, fabsf(vec.y / vec.z));
m_near = min(m_near, vec.z);
m_far = max(m_far, vec.z);
}
m_fovx = atanf(maxx);
m_fovy = atanf(maxy);
}
