We got hired by a company that was developing a remote-controlled baseball launching machine. The machine itself was just the standard two spinning wheels (although the max rotational speed of 125 mph was a lot for this sort of thing), but it could also pivot 360 degrees and also angle itself between straight up and 45 degrees down towards the ground, so it was capable of simulating any hit ball in baseball. The idea was that you would put this machine at home plate and then the coach could walk out among the players and use the remote (which was a Windows Mobile PDA) to generate any kind of hit, like a grounder to short or a pop fly to right field etc. Because the wheels could be independently controlled, you could put any kind of spin you wanted on a ball by having one wheel spinning faster than the other.

Really a cool device and a cool project, but my coworker who got the gig was a remarkably terrible programmer who spent more than a year fucking things up in various ways. At one point, for example, he spent three months trying to develop a Physics engine to control where the ball went, despite the fact that a) he knew nothing about Physics, and b) the Physics of a spinning baseball is actually incredibly complicated and well beyond the processing power of a PDA circa 2005. Not to mention that the balls used varied tremendously in how old and scuffed up they were, which would have defeated any attempt to calculate where they were going with any kind of real precision.

Despite being well over budget and past the original schedule, he had things sort of working (sometimes) and the client asked him to produce a variant of the software that would let the machine be used by Little League coaches. My coworker in addition to writing the version to scale back the speeds appropriately, also decided to completely change the API that was used to communicate with the machine. Previously, the speeds had been specified by short integer values between 0 and 32768, but he decided it would be better to use floating-point values between 0 and 1. All well and good, except his way of dealing with the huge amount of compiler errors this generated was to cast all the hard-coded short int values as floats and clamp the result between 0.0 and 1.0.

As bad as this was, he also decided to test this version - for the first time - on a field with actual Little Leaguers (in his defense - but only slightly - we rarely had access to the actual machine itself, so proper testing was always difficult). The coach sent the command for a slow grounder to the shortstop. This should have produced a horizontal ball with about a 30 mph speed on the bottom wheel and 35 mph on the top wheel to give it some topspin. Instead, his hard-code int values were about 10000 and 12000, which got cast and clamped to 1.0 by the API call - in other words, maximum speed (125 mph) on both wheels. This ejected a ball with no spin going 125 mph, the most deadly knuckleball in human history (human pitchers throw knucklers at maybe 50 mph and they're nearly impossible to hit or even catch). At least he had the angle and azimuth "right" so this was fired straight at the shortstop! Had it hit him, the kid for sure would have badly concussed and very possibly killed, but fortunately it sailed just over his head.