The Quiet Flicker of Invincibility

Lots of good work done yesterday. Insomnia will do that from time to time, keeping me up into the wee hours with little to occupy my time but lots of things that would like to get done. I’ll start with the levels. The Desert stage (as opposed to the Dessert stage natch) is in the bag now. Again, not saying anything in terms of how “complete” it is, since it still requires tuning and balancing and background element placement and multiplayer enemies and whatnot, but it does play and it plays pretty well. The unique (for that level) combination of flying enemies with lots of ground really makes the level play in a distinct kind of way. I’m rather fond if its peculiarities. Actually though I find that all of the levels play in a distinctive way, which makes me happy. Almost like an italian restaurant – the ingredients are almost all the same, but the combinations make for some distinctive tastes.

I also got the background elements popping a little bit more, which falls squarely into the “good” category. So now Paper Zeppelin has background clouds in it. I discovered that the structure called Vector2 can handle float variables. I’ll back that up just a bit. In C#, there is a special kind of command called a Vector2 that holds an X and Y variable. You can start one up like this:

Vector2 Position = Vector2.Zero;

What that means is to start a Vector2 type variable and make it (0,0). You could also do this:

Vector2 Position = New Vector2 (0,0)

…or any other numbers. But I tend to like the first way, since it has a special command and everything.

Oh, and by the way, if you were dealing with 3D stuff, there is something called Vector3, which also keeps a Z variable.

Anyway, with Vector2 you have an X and a Y variable, and those can be changed independently. So you can do this for example, once you’ve set up the variable:

Position.X = 5;

…which makes the X value 5, leaving the total values at (5,0).

In Paper Zeppelin I use a couple of these to track things that have X and Y values, namely position (hence the example) and speed. With speed what I’m actually doing is showing the change in position, so almost everything has something like this in it’s little robot update code:

Position.X = Position.X + Speed.X;

That way, everything that would change the speed of an object only changes the speed value. In contrast, The Thief’s Tale handled everything by modifying just the position of the objects on screen. That worked only because I was dealing with so few objects (like 1-2, tops depending on whether or not something was trying to stab you). That would fall down in Paper Zeppelin, the code just wouldn’t work.

Anyway, this is all a long way of saying what I started with, mainly that I can set the X and Y values of a Vector2 as float variables (less than whole numbers). So I can say, set the speed for the backdrop at 1, which moves the backdrop a nice slow 1 pixel per frame. The ground all moves at a speed of 2, so when I have them both it creates a nice parallax effect (this not this).

When I put clouds in though, I really wanted to create a multiple layer parallax effect. When things move at lots of different speeds and are stacked correctly, it implies a lot of motion and a great deal of depth. So for kicks I told the clouds to move at a speed of 1.5, and wouldn’t you know it, they move slower than the ground but faster than the backdrop. The 3D effect is pretty ice cold (which is cooler than being cool). Also, since I can stack things up pretty high and float variables can be staggeringly specific (I can make the clouds move at 1.12345 pixels per frame if I felt like it), the Paper Engine can officially handle more things at the same time than the Super Nintendo is capable of doing. Sweet.

Getting to the titles, I got the player lives system to work right. So now, if you die it creates a crasher (’s a work in progress) falls to the ground and leaves a smoking Hindenburg-esque wreck. Then, if you have lives it spawns up a new player of the same type that just got taken out. Hypothetically, if player 4 eats crap, it’ll spawn up another player 4, which is good since the controller assignment is tied into the player number. Further, when you pop back into the world the game makes you invincible for a short period of time.

I did this using a 2 step process. First, when you spawn up you get 150 hp. The robot code for each player says that if you have more than 3 hp, to go ahead and subtract 1 every frame. So during this period if a player is hit, they just take the shot. Losing 1 hp from whatever doesn’t really matter when you have 100+.

Second, I told the draw code to draw players if they had fewer than 4 hp (the normal amount) or if they can more than 3 and the hp was an even number. Hence, only draw every other time if you have more than the normal amount of hp. What that does is make you flicker just a bit and appear transparent for the most part. It looks good, really good. Like the kind of thing that would be in a Super Nintendo game, provided it could handle the parallax awesomeness.

I’ve been through the desert on a horse with no name…It felt good to be out of the rain…In the desert you can remember your name…

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