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benj
07-03-2004, 04:18 AM
Hello.
I'm drawing polys using ARB_multitexture
and EXT_env_combine
thanks to the env_combine i can do (2 pass)
t0 * t1
t0 + t1
t0 + t1 -0.5 etc...
Now what i'd like to do is modulate the result
by glColor (still using 2 pass!)
=> t0 * t1 * color
=> (t0 + t1) * color (or t0*color + t1*color)
=> (t0 + t1 -0.5) *color
(well actually the first one is working)
or i can only modulate the first texture unit (t0)
by glcolor
i suppose this is a env_combine limitation, right?
what extension should i look at?
secondary color?
or the only solution is 3 passes?
thanks for your help

ben

CrazyButcher
07-03-2004, 06:16 AM
btw there is also an ARB version of that extension

other than that to do what you want to look into NV_combine4 or ARB_crossbar

crossbar/combine4 allow pointing to other texture units like
tex0 = t0 + t1
tex1 = prev * color

combine4 as the name says also allows combination
a * b + c * d

benj
07-03-2004, 09:51 AM
do you have any link that points
to code example using crossbar extensions?
thanks

CrazyButcher
07-04-2004, 01:54 AM
afaik the only new thing is that when you define a src in tex_env_combine, you can use other texunits as source like:

glTexEnvi (GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_TEXTURE1_ARB)

before a src could only be
GL_CONSTANT, GL_TEXTURE, GL_PRIMARY_COLOR, GL_PREVIOUS

now you can do
GL_TEXTUREi_ARB
as well