Some UI elements can have variants to be switched for one another in case of different circumstances. In that case the variant switch needs to be seamless, meaning that the images for those elements need to be of the same size and with the same base position.
Note the bar, it is missing from the variant files themselves, but can be added within unity and be programmably extended or shrunk from the bottom of the thermometer.
UI elements can also consist of several parts to be layered on top of each other and programmed to be moved, colored or otherwise changed separately.
As an example, the atmospheric pressure meter consists of 3 parts: the base with a dial, the arrow to rotate and indicate the overall pressure on the base’s dial and an exclamation mark, to be colored and/or flashing in case of dangerous atmospheric conditions. The text for the exact atm amounts is added within Unity, using accepted project fonts, so it can also be changed programmably.
Same principle applies to the target dummy, surgery dummy and other complex UI elements.
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