Articles

I’d
like to start this article with the statement “Many people ask
me …” as if I’m in the middle of a whirlwind of
interest in my activities. However, game development is a fairly solitary
process and the most common thing people ask me is some variation
of “Would you like fries with that?”

So in my own alternative
universe many people ask me, “What is the story behind the game
engine used in Slip Space: The Burma-Shave Analogy?”

Initially, I vaguely recognized
the functionalities that would be needed to develop a game but didn’t
know they were packaged under the name “game engine.”
As such, I didn’t go to a third party to procure one. I thought
that was covered by the multi-media program Director. Director comes
with Lingo, its own programming language, so as it gradually occurred
to me that I needed a unifying scheme to pull the process together,
I wrote my own game engine.

Even though I was developing
the project as a one-person operation, I proceeded as if it were a
collaboration between a programmer and a designer. With this approach,
the programmer provides functionality for generic objects and the
designer creates specific instances of those objects.

For example, a game contains
many scenes and those scenes contain images. A scene can be as simple
as a single still image or it can contain numerous layered images,
some visible only if certain conditions are true. Moreover, some of
these images can be moving, changing size or fading in and out. Beyond
considering the images, there must be a way to exit the scene with
either a directional cursor, as in a navigation scene, or after a
number of frames, as in a cut scene.

I named the objects used
in the game engine “design formats.” The format for the
object aNavigationScene (somewhat simplified) is as follows:

Navigation,
aNavigationMap
Forward, aNavigationScene or aCutScene
or none
Left, aNavigationScene or aCutScene
or none
Right, aNavigationScene or aCutScene
or none
Up, aNavigationScene or aCutScene
or none
Down, aNavigationScene or aCutScene
or none
Images, aNumber, anImage, anImage
…
Hotspots, aNumber, aHotspot, aHotspot
…

Applied to
a specific scene, in this case navigation scene 121F, it reads as
follows:

Navigation,LRU200800500
Forward,none
Left,121LF
Right,121RF
Up,121MU
Down,none
Images,8,121FSky,121FSkyOver,121FBeam,121FFront,121FPanel,121FRing1,121FRing2,121FRing3
Hotspots,1,121FPanelHS

Nested within the format
of aNavigationScene are references to other objects, namely aNavigationMap,
aCutScene, anImage, and aHotspot. As you
probably guessed, these have design formats as well.

Clearly this scheme creates
a hierarchy of objects that the designer places and the program interprets.
In order to create interesting visual effects, the design format for
the object anImage allows the designer to specify image properties
such as size, location, rotation and blend. Further within that format,
the designer can reference the object anAnimator that dictates
how these properties will change over time.

Returning to the navigation
scene 121F, Exhibit 1 shows a screen capture of that scene. An isolated
version of the front image is shown in Exhibit 2 while the blend-animated
elements, the Beam, the Panel, and the Rings, are isolated in Exhibit
3. In the full glory of the game, these elements are each flashing
at different rates. Additionally, the sky is evolving as the SkyOver
image blends in and out.

Exhibit 1

Exhibit 2

Exhibit 3

I confess I started designing
the game before I completed the game engine. Early on I even changed
some functionality, which meant I had to change content. However,
once I got into it and had a considerable amount of content tied to
the game engine as completed, I stopped changing it and started adding
functionality only as I had something in mind that the game engine
didn’t support.

Given my experience, I’ll
revisit and optimize the design of my game engine before I start the
sequel, “Fine Patio Furniture of Slip Space.”

For more on Slip
Space: The Burma-Shave Analogy as featured on Just Adventure,
check out the Randy Sluganski Exclusive
Preview and the first
installment of my Developer’s Journal.

Many people ask me, “Is
that really the title of the sequel?”

No, I’m just kidding.