void Frustum<NumericT>::build_frustrum_from_matrix (const Matrix<4, 4, NumericT> & m)
{
// The constructor used for Plane will normalize its elements automatically
// Left (m3 + m0)
_planes[LEFT] = convert_plane_from_matrix_eqn(m.at(3, 0)+m.at(0, 0), m.at(3, 1)+m.at(0, 1), m.at(3, 2)+m.at(0, 2), (m.at(3, 3)+m.at(0, 3)));
// Right (m3 - m0)
_planes[RIGHT] = convert_plane_from_matrix_eqn(m.at(3, 0)-m.at(0, 0), m.at(3, 1)-m.at(0, 1), m.at(3, 2)-m.at(0, 2), (m.at(3, 3)-m.at(0, 3)));
// Top (m3 - m1)
_planes[TOP] = convert_plane_from_matrix_eqn(m.at(3, 0)-m.at(1, 0), m.at(3, 1)-m.at(1, 1), m.at(3, 2)-m.at(1, 2), (m.at(3, 3)-m.at(1, 3)));
// Bottom (m3 + m1)
_planes[BOTTOM] = convert_plane_from_matrix_eqn(m.at(3, 0)+m.at(1, 0), m.at(3, 1)+m.at(1, 1), m.at(3, 2)+m.at(1, 2), (m.at(3, 3)+m.at(1, 3)));
// Near
_planes[NEAR] = convert_plane_from_matrix_eqn(m.at(2, 0), m.at(2, 1), m.at(2, 2), m.at(2, 3));
// Far (m3 - m2)
_planes[FAR] = convert_plane_from_matrix_eqn(m.at(3, 0)-m.at(2, 0), m.at(3, 1)-m.at(2, 1), m.at(3, 2)-m.at(2, 2), (m.at(3, 3)-m.at(2, 3)));
// Calculate object-space points for box coordinates:
AlignedBox<3, NumericT> clip_box(-1, 1);
Vec3u k(2);
auto inverse_view_matrix = inverse(m);
for (std::size_t i = 0; i < 8; i += 1) {
_corners[i] = inverse_view_matrix * clip_box.corner(k.distribute(i));
}
_near_center = inverse_view_matrix * Vec3T(0, 0, 1);
_far_center = inverse_view_matrix * Vec3T(0, 0, -1);
}
bool FrustumT<T>::contains( const AxisAlignedBox &box ) const
{
for( size_t i = 0; i < 6; ++i ) {
if( mFrustumPlanes[i].distance( Vec3T( box.getPositive( vec3( mFrustumPlanes[i].getNormal() ) ) ) ) < 0 )
return false;
else if( mFrustumPlanes[i].distance( Vec3T( box.getNegative( vec3( mFrustumPlanes[i].getNormal() ) ) ) ) < 0 )
return false;
}
return true;
}
RectT<T> RectT<T>::transformed( const Mat3T& matrix ) const
{
Vec2T center = Vec2T( x1 + x2, y1 + y2 ) / (T) 2;
Vec2T extents = glm::abs( Vec2T( x2, y2 ) - center );
Vec3T x = matrix * Vec3T( extents.x, 0, 0 );
Vec3T y = matrix * Vec3T( 0, extents.y, 0 );
extents = Vec2T( glm::abs( x ) + glm::abs( y ) );
center = Vec2T( matrix * Vec3T( center, 1 ) );
return RectT<T>( center.x - extents.x, center.y - extents.y, center.x + extents.x, center.y + extents.y );
}
void RectT<T>::transform( const Mat3T &matrix )
{
Vec2T center = Vec2T( x1 + x2, y1 + y2 ) / (T) 2;
Vec2T extents = glm::abs( Vec2T( x2, y2 ) - center );
Vec3T x = matrix * Vec3T( extents.x, 0, 0 );
Vec3T y = matrix * Vec3T( 0, extents.y, 0 );
extents = Vec2T( glm::abs( x ) + glm::abs( y ) );
center = Vec2T( matrix * Vec3T( center, 1 ) );
x1 = center.x - extents.x;
y1 = center.y - extents.y;
x2 = center.x + extents.x;
y2 = center.y + extents.y;
}
void FrustumT<T>::set( const Camera &cam, const Vec3T &ntl, const Vec3T &ntr, const Vec3T &nbl, const Vec3T &nbr )
{
Vec3T eye = Vec3T( cam.getEyePoint() );
T farClip = cam.getFarClip();
Vec3T ftl = normalize( ntl - eye ) * farClip;
Vec3T ftr = normalize( ntr - eye ) * farClip;
Vec3T fbl = normalize( nbl - eye ) * farClip;
Vec3T fbr = normalize( nbr - eye ) * farClip;
set( ntl, ntr, nbl, nbr, ftl, ftr, fbl, fbr );
}
bool FrustumT<T>::intersects( const Sphere &sphere ) const
{
return intersects( Vec3T( sphere.getCenter() ), (T)sphere.getRadius() );
}
bool FrustumT<T>::contains( const Sphere &sphere ) const
{
return contains( Vec3T( sphere.getCenter() ), (T)sphere.getRadius() );
}
