Product: Camouflage
Chameleon Camouflage   (+1)  [vote for, against]
Like a mood ring, only for war.

There are fabrics, fabric dyes and ink formulations that change color under different conditions: light (+IR & UV), temperature, humidity, and angle of viewing. (There are probably substances that react to gamma rays, but I'll leave that for later.) What if you combined these attributes and could use them in combination to create a camoflage that changed with the conditions.

Some fabrics have a nap, a direction that light reflects from. If you varied this in areas and changed the weave, would the inclusion of special threads alter the visibility in infrared? Is there something that can be done to foil RF? UV?

If you used light-sensitive dyes your daytime dappled forest pattern could change to a somber blue and black colorway at night, gradually darkening by responding to dusk and keeping you low contrast to your surroundings. In broken bright sunlight the exposed areas would go to pale tints and the shaded areas would get more saturated, mimicking the hard edges.

If it was dismal and rainy, the humidity could change a forest pattern to a mud puddle. Marines drying out going ashore from their landing craft would morph from sea-blues to sand-dune and scrub, then into forest cover. Parachutists go from sky-blue with clouds to grassy field. Lack of body heat defines a casualty, and a pattern could show that.

If not made into uniforms, a tarp or poncho or net could be used. Like current camo patterns the effects, colors, and shapes (if any) would be tailored to the unit requirement.
-- minoradjustments, Sep 08 2023

An overview of chromic materials [a1, Sep 08 2023]

(sorry, most of the better articles are behind paywalls) [a1, Sep 08 2023]

baked. no?
[pashute, Dec 27 2023]

//Is there something// no, there is nothing, everything is an illusion.

//your daytime dappled forest pattern could change to a somber blue and black colorway at night,// ask your manservant about dressing for dinner.
-- pocmloc, Sep 08 2023

To answer your question "Is there a material ...?" the answer is probably yes. There's been a lot of research on chromic materials for technical textile applications, but most of the available papers I've found so far are behind paywalls.
-- a1, Sep 08 2023

[pocmloc] Perfectly ordinary colors made lucid on command.
-- minoradjustments, Sep 08 2023

[a1] Good article. If we include electrochromism we will include a vibratory component in the pants.
-- minoradjustments, Sep 08 2023

Are those pants made of chromic textiles or are you just happy to see me?
-- a1, Sep 08 2023

//behind paywalls// Didn't we used to have people for that, obtaining the Unobtainium and so forth?
-- Sgt Teacup, Sep 09 2023

Yes, but we can't find them; they're too well camouflaged.
-- pertinax, Sep 09 2023

random, halfbakery