Brokered convention

I'm going to briefly toy with some nomination scenarios. 

i) On one scenario, Trump cinches the nomination outright by winning enough primaries to net 1237 delegates or more. 

That process would be accelerated if his competitors drop out. Or it's possible that he can garner 1237 delegates even if his competitors remain in the race.

ii) But in another scenario, what if Cruz and/or Rubio have enough money to stay in the race right up to the convention, and one or both pick up enough delegates to deny Trump the magic number. He wins a plurality of the delegates, but falls below the 1237 threshold. 

In that event, the nomination would be settled at the convention itself. If Trump doesn't have 1237 delegates by the time of the convention, will he get the nod anyway? I don't know.

Here's one potential hurdle: if he continues to win primaries, but maintains his pattern of only skimming about one-third of the vote, with the other two-thirds going to the remaining anti-Trump candidate(s), would the convention nominate a candidate whom about two-thirds of the party can't stand?