Airships and Assisted Flight


In COZ, the Bummers (who, if the name is too subtle, are the bad guys), spawn from airships.  At least, that’s been the plan.  This was pretty easy to get running in the game, but the ships weren’t grappleable (I’m just going to pretend that’s a real word from here on out 🙂 ).  What fun are airships you can’t dangle from?  Up to that point, there had been two types of object in the game, both of which were grappleable.  Static objects like buildings and trees, and AI objects.  In both of these situations, most of the forces being applied are at the player’s end of the rope.  When you latch onto a building, the other end of the rope stays in place.  When you grapple a cit, it goes ragdoll and is at the mercy of the player’s virtual hand.  The airship, on the other hand, is going to keep on moving.


I’ve been using a product for Unity from Ultimate Game Tools called Ultimate Ropes.  It’s been fantastic, but required a lot of modification to use in COZ.  It takes a set of parameters and creates a rope out of Unity’s stock configurable physics joints.  While the rope looks nice and ropey, in the engine its really a linked chain.  Each link can be accessed and modified, and that was the trick to the airship’s grapplibility (also a word now).  There were a lot of other adjustments that had to be made (like getting an airship AI to stop trying to step over the rope that was attached to it!), but adjusting the link nearest the ship required the most trial-and-error.

It works now!

I had to add one last, critical change to the rope’s properties.  They had to be breakable.  Imagine you grapple two airships, one with each hand,  traveling in opposite directions.  When the ropes have extended all the way, the physics engine goes haywire.  Each link is being stressed beyond capacity.  The results are not pleasant.  When enough force is applied to a rope now, it will snap and fall lifeless to the ground.


I’ve added the image above to show the scale of the airships.  In this screenshot, dangling from the rope underneath the airship, you can spot Coz.  The ships are big.  They aren’t the prettiest, most graceful things, but that will change over time. Hitching a ride on one of these and being swept through the level is really intense.  If you time it right, you can even try to catch another ship in passing.

I’ve added two more features I’ll be discussing next.  One functional, one fun 🙂

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