// We need to calculate the texture space direction. It depends on the mapping.
if (isTriplanar)
{
// Note: The TBN is not normalize as it is based on mikkt. We should normalize it, but POM is always use on simple enough surfarce that mean it is not required (save 2 normalize). Tag: SURFACE_GRADIENT
// For planar the view vector is the world view vector (unless we want to support object triplanar ? and in this case used TransformWorldToObject)
// TODO: do we support object triplanar ? See ComputeLayerTexCoord