Accessing tangent basis for other UV channels in Max?

Rigging
1

Does Max store the tangent/binormal vectors for UV channels other than 1 anywhere? I’ve tried accessing them using the TANGENT1 etc vertex input semantics, but they just return a constant flat value across the entirety of the mesh - TANGENT0 works as expected, returning the same UV1-based tangents as the TANGENT semantic, but higher values for the TANGENT semantic don’t appear to contain anything. Does Max compute the tangent basis for all the UV channels, or do you have to manually calculate anything over UV1?

2

Maybe you need to properly redefine the texcoords. In order to get DirectX to read Max’s vertex colors, you need to explicitly define the texcoords because Max’s UV channel order is a mess. So maybe the same applies to the tangent/binormal stuff too? I’ve never tried multi-channel normals before so I am unsure.

try it and see. Something like this:

int texcoord0 : Texcoord
<
	int Texcoord = 0;
	int MapChannel = 1;
	string UIWidget = "None";
>;

int texcoord1 : Texcoord
<
	int Texcoord = 1;
	int MapChannel = 0;
	string UIWidget = "None";
>;

int texcoord2 : Texcoord
<
	int Texcoord = 2;
	int MapChannel = -2;
	string UIWidget = "None";
>;

int texcoord3 : Texcoord
<
	int Texcoord = 3;
	int MapChannel = -1;
	string UIWidget = "None";
>;
3

Interesting idea! If this is how the tangent basis for other channels is stored, however, I’m not guessing the right keywords to access them. Unfortunately it doesn’t seem there is any documentation for how the 3DSMax HLSL scripting works (outside of the included sample shaders.)