gl_NormalMatrix

[l99057j]

I am writing a shader that needs the normal matrix. Reading online, it looks like the following is the definition of a normal matrix...

the transposed inverse of the upper 3x3 of the product of the Model and View matrices

So my first inclination is to use a named_parameter_auto with inverse_transpose_worldview_matrix. But the documentation doesn't make it clear whether this takes only the upper 3x3 or is using the whole matrix. Can anyone elaborate on this and tell me if I'm using the right thing or there is a better alternative?

[bstone]

You should use only the top 3x3 block from that matrix to transform normals.

[scrawl]

I think if you set the w component (of the vector you are multiplying with the matrix) to 0, you could also use the 4x4 matrix with the same result.