i still don't understand how this works.

i have an effect which uses 3 texture stages:

colormap
detailmap
shadowmap

the shadow map does only contain shadows and no lighting information (white = no shadow, black = shadow). so i use modulate and not modulate2x.

for older cards i would like to render the shadow map in a second pass.

i enabled alpha blending and tried all

SrcBlend
DestBlend

combinations but nothing worked properly. what exactly is the source and what the destination? what do i have to set as colorop in the second pass? how does rendering such an effect in two passes work? do i need an alpha channel?

I have been screwing with this a little too. To see Pass p0 an p1 you will
need to look at the fixed-function multitex at my site/





The basic way I am adding a shadow map is this way, and it is happening
in Pass p2:

Pass p0
{
.... lay down the base skin
.... using tex[0]
}

Pass p1
{
.... Add a second texture using an alphamap
.... Using Texture 0,1
}

Pass p2
{

alphaop[0]=disable; // Frame buffer is filled, but no alphaops wanted

alphablendenable=true;

SRCBLEND=ZERO; // <<<<<<<<<<<<<
DESTBLEND=SRCCOLOR; // <<<<<<<<<<<<<

zenable=true;
zwriteenable=true;
ditherenable=true;

Texture[1] = <mtlSkin2>;

magFilter[1]=linear;
minFilter[1]=linear;
mipFilter[1]=linear;

TextureTransformFlags[1] = disable;

texcoordindex[1]=1;

}

thanks! i got it to work. the reason for the problem was this:

first pass:

colormap
detailmap

second pass:

shadowmap
disable

if you don't disable the second texture stage of the second pass it uses the same settings as in the first pass which leads to strange results!

I see...

Your note about disabling the pass 2/ stage 2 operations made sense.

I made a new project, did not do any masking of textures and disabled the 2nd stage of pass 2. In the earlier reply I think I had to disable AlphaOp because I was using alphamap in the previous passes. I suppose I could have done that in the 2nd stage as well.

Here are some shots for comparing shadow, diffuse light, and just a detail map.
web page