Someone

ps_1_4

////////////////////////////////
// r0: alphamaps
// r1 - r4: textures
////////////////////////////////

// Sample textures
texld r0, t0
texld r1, t1
texld r2, t1
texld r3, t1
texld r4, t1

// Combine the textures together based off of their alphamaps
mul r1, r1, r0.x
lrp r2, r0.y, r2, r1
lrp r3, r0.z, r3, r2
lrp r0, r0.w, r4, r3