[attachment=33625:1.PNG]

The vector I and n are given, n is the unit vector, the output is vector r.

my question is the orientation of dot(n,l)*n.

Since dot(n,l) is the signed length(negative in this case)

why "the vector below n" still need to multiply by "n" , and why the vector dot(n,l)*n and "n" have opposite orientations.(assume that "dot(n,l)" is a scalar,after it multiply by "n", it should have the same direction as "n" )

[attachment=33626:??.PNG]

In my opinion ,it should be

[attachment=33627:??1q.PNG]

why "the vector below n" still need to multiply by "n" , and why the vector dot(n,l)*n and "n" have opposite orientations.(assume that "dot(n,l)" is a scalar,after it multiply by "n", it should have the same direction as "n" )