DX11 alphamask

achim · November 1, 2015, 2:36pm

I’m struggling here with a really really tough shader:
Swizzling the alpha channel and multiplying with a value.

omg

I don’t know why this won’t work like it did in dx9.

please help me out
thx

VVVV.7z (1.9 kB)

everyoneishappy · November 1, 2015, 2:56pm

attach a Blend (DX11.RenderState)

achim · November 1, 2015, 4:22pm

looks the same :/
tried all modes

everyoneishappy · November 2, 2015, 6:06am

Are you sure?

achim · November 2, 2015, 10:33am

ugh I never checked, I expected a green picture.

I want to use the gradient as an alpha mask for the green quad.

Could you point out my mistake?

soriak · November 2, 2015, 12:47pm

the dynamic gradient input is the problem…
you applied the gradient onto “lightness” instead of “alpha”.

attached a version that reads the lightness (in terms of blue) inside of the shader.

swim swim

achim · November 3, 2015, 9:46am

I thought multiplying colors works like this:

p1.rgba (0,1,0,1) * p2.b (0.5)
p1.rgba (0,0.5,0,0.5)

and

p1.a (1) * p2.b (0.5)
p1.rgba (0,1,0,0.5)

no?

soriak · November 3, 2015, 10:38am

from your shader:

bildout = bild2.a * ((bild1.r + bild1.g + bild1.b)/3);

you assign a single value to a float4, no Color, only alpha multiplied by the greytone.

try:

bild2.a = ((bild1.r + bild1.g + bild1.b)/3);
return bild2;