Modeling Jack's World

[VernJensen]

Okay, I'm not going to try to convert my units into yours, but let me introduce mine:

1) Frames - this refers to a frame of animation. If you were to slow everything way down, then each

change

in the animation occurs in a single frame. The game runs at 60 frames per second, or fps.

2) All of my units are in

pixels per frame

. Tiles are 16 pixels wide and tall, not counting the fringe. So convert my values into your tile-based values if you want, but they're given in terms of pixels in the code.

Here are some values, given in pixels per frame, for Jack:

Walking speed - 2.5 ppf
Climbing speed - 2.2 ppf
Pole sliding speed - 6.0 ppf
Maximum falling speed - 12 ppf
Gravity - 1.3 ppf (i.e. most objects accelerate by this amount per frame)

That's all I got. Jumping is tricky, so I can't really explain it. It's different from falling though. The mechanics are totally different. He normally falls much faster than he does during a jump.

I can't answer most of your other questions, except for a couple:

1) How fast does he travel horizontally while falling?

Same as normal, I think. It's just that he falls so darn fast (12 ppf within a few frames) that his horizontal movement speed is quite small by comparison.

2) What is the conversion factor between the speed number you type into the dialog box and tps? Is this factor the same for all sprites that can have a speed?

The answer to this question is interesting. You see, in old-style Mac dialog boxes, you couldn't enter fractional values, like 2.5. And I wanted that for the monsters. So instead what I did was divide all entered values by a certain number one they were loaded. For instance, if I divided by 2, and you entered

5

in the dialog, you'd get a speed of 2.5 ppf. But for some monsters I wanted more of an ability to have lots of fractional values than I needed for others. So the medusa heads are divided by something like 10 or 20 (I could look this up if you really need to know), while I think certain other monters aren't divided by anything, and some are divided by fairly small numbers, like 2 or 3.

3) How fast does a big spider descend/ascend? (tps)

You're going to have to convert ppf to tps yourself. But here are the ppf values:

Descend speed - 1.8 ppf
Climb back speed - 0.6 ppf
Delay between drops - 60 frames

4) How far before Jack dies?

7 tiles


Interesting idea you have to be so mathematical about everything, but honestly, even as the designer of the game, I'd do everything by trial-and-error myself.