title: What is a "Push-Constant" in vulkan?
body: <p>I've looked through a bunch of tutorials that talk about push constants, allude to possible benefits, but never have I actually seen, even in Vulkan docs, what the heck a "push constant" actually is... I don't understand what they are supposed to be, and what the purpose of push constants are.  The closest thing I can find is this <a href="https://computergraphics.stackexchange.com/q/5536/6530">post</a> which unfortunately doesn't ask for what they are, but what are the differences between them and another concept and didn't help me much.</p>
  
  <p>What is a push constant, why does it exist and what is it used for? where did its name come from?</p>