Thursday, March 31, 2011

Bally Roller and the Order of the Edits

The most strained post title ever? Perhaps. I ran out of "Die Hard" movies, so I'm moving over to "Harry Potter." I don't know what I'll do when it comes time to make my eighth video. "Friday the 13th" movies, maybe? Not enough franchises made it past seven entries.

Anyway, I now have a very basic form of cutting implemented! Let's go to the tape:

In this video, I'm first showing just the ball rolling down the simple slopes, with the red camera tracking it; then, I release both the simple ball and the pachinko ball, and allow a camera to follow each one. The green camera is also set to cut more often than the red camera. Pachinko is just more exciting to watch, I guess.

Since I wanted to start with very simple editing, the cameras currently only cut back and forth between two shots: a tracking shot from behind the target, and a stationary shot which pans with the target. Here is a diagram of the behavior tree that the cameras are implementing:

That may be confusing, so I made a simpler version as well, with more words and less cryptic arrows. Also, more bright colors, and harder-to-read text. Let's take a look at that version:

Hopefully that one will help. Basically, the camera has two branches for whether it's currently engaged with an event or not (originally I was going to have the camera wander aimlessly when not engaged, but I disabled that for the video above). When it is engaged, it enters a shot idiom, which is a sequence of commands for handling a certain type of event. In this case, there's only one idiom: cut to a tracking shot behind the target, wait a certain amount of time, cut to a stationary side shot, wait, and repeat (until no longer engaged). Having shot idioms also helps deal with issues like the 180-degree rule (I never made a post about Editing Rules, did I? Don't worry, I will), since we can make sure that the next shot doesn't violate anything with respect to the previous one.

Obviously this is just the foundation for the cutting system, but behavior trees make it easier to build off of this. The next step will be to implement a wider variety of shot choices (establishing shots, reverse tracking shots, aerial shots, etc). After that, I will implement more idioms for handling different types of events (a dialogue scene between two characters is probably the most important one). The shot lengths will be variable eventually too, so that cuts don't happen so regularly.

Anyway, beta reviews are coming up pretty fast. I'm planning on having more shot choices added by then, and I'm going to play around with more type of events. I'm going to try to have multiple idioms as well, but they probably won't be as complex as dialogue or crowd scenes. Still, we'll see. Stay tuned for "Bally Roller and the Half-Shot Idiom" next week!


  1. Star Wars will give you another 6 options. More, if you include the books. Not to mention Star Trek has a lot... or you can move on to James Bond movies. That could get interesting.

  2. Ooh, Bond movies are a good idea. I can't use Star Wars, since I'm already up to the 6th entry in my series: I'm not just taking random movie titles, I'm using them based on what number they are in a franchise.

    I will make an exception for "Electric Boogaloo" because that is the best sequel title ever.