Those calculations are for converting the normal in the normal map between color and euler space. The normal stored in the normal map needs a basis (ie: transform matrix) to act as a frame of reference so the renderer knows how to orient the normals in the map to the topology . That basis is derived from information in the Texture UV space, geometry normal, and Tangents and BiNormals vertex color properties.
I need the algorithms for the computation of the basis, and I need to know how ultimapper compensates for the case when the binormals are not present. For example, does ultimapper assume the basis will always be orthogonal and do a cross product of the tangent and geometry normal to generate the binormal? Matt From: [email protected] [mailto:[email protected]] On Behalf Of francisco criado Sent: Wednesday, December 04, 2013 3:36 PM To: [email protected] Subject: Re: tangent/binormal space computation Hi Matt, will this help? http://softimage.wiki.softimage.com/xsidocs/tangents_binormals_SettingtheDataTypeforTangentsandBinormals.htm#Rga95703 Francisco. 2013/12/4 Matt Lind <[email protected]<mailto:[email protected]>> I need to write a variant of ultimapper to support our proprietary workflows, but our content (tangent space normal maps) currently uses the softimage standard. I need to know the algorithms Softimage uses so I can make an accurate conversion to our proprietary standards. Specifically, I need to know: - how the vectors are computed in the Tangents and BiNormal vertex color properties - how Ultimapper does a tangent space normal transfer when only a Tangents vertex color property exists on the hi res mesh. (eg; what assumptions does it make / what calculations does it do to compensate for lack of binormals?) Matt
