As far as I know there are two functions (or maybe more) that take care of the crates spawning.
If I'm correct, one uses an area established by the user, and the other uses coordinates.
The functions have 3 inputs, one for the location(if it is in coordinates then there are two inputs, one for the X and the other for Y), the other for the type of the materials, and the last for the quantity. And If I'm not wrong, there should be one input more that is expressed with a boolean logic (true/false), that belongs to if it appears materialized (with the flash and the boom) or as if it was already there (spawns in a simple way, without booms or etc.)
You can find those functions in the Downloads section, in the "SAIL Functions" document.
Hope this was helpful.
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