Supposing to have two textures bound on, respectively, texture unit 0 and texture unit 1.
Modulating them (t0 * t1), is there a way to obtain:

t0.r * t1.r
t0.g * t1.r
t0.b * t1.r
t0.a * t1.r

What I need is to consider all the t1 channels equal to t1 red channel.
Is there an operand that realizes this?

Thanks in advance.