i think luminosity mapping basically works like that:

Code:

---

pixelShader=

asm

{

  ps.1.3

  def c0,1,1,1,1

  tex t0 // sample shadow map

  tex t1 // sample color map

  tex t2 // sample luminosity map (luminosity is defined in the alpha channel)

  modulate2x r1,t0,t1 // modulate colormap with shadowmap

  lrp r0.rgb,t2.a,r1,t1 // interpolate between shaded color map and unshaded color map depending on luminosity map

  +mov r0.a,c0.a

};

---

(not tested)

a6 only supports 16 bit level textures so the luminosity map needs to be a separate texture. without this restriction the luminosity channel could be included in the color map.

if i have some time i will give this a try and look if the same is possible without a shader.