25.12.12

My coding project, part III

Wherever my nose points at

Now that I had finally fixed the rotation and found out where the hell it's pointing at, the last of the unimplemented basic functions was the movement. My first attempt was, especially in hindsight, ridiculous: if the angle was pointing to one of the cardinal directions, the full acceleration was applied on one axis - if somewhere in between, the acceleration was applied to the two closest ones. While testing it first looked nice, but in a while I noticed that "Heeeeyyy.. this thing jerks around when it's turning and accelerating. It looks pretty odd now". Even the slightest difference from a 3π/2 angle made the polygon accelerate at full speed towards the closest intermediate direction. Whoops.

A bit more realistic change of speed

After a very short but intense moment of screen-staring a lamp went off in my head: if I went and used the same damn trigonometrical functions that told me where thing was facing but using the known speed and angle to get the Δx and Δy values, I'd be done! So, the same trick but opposite direction. Luckily it didn't take me more than a couple of minutes to come up with this.

tempspeed = Vector(self.speed.x, self.speed.y)
dy = math.fabs((math.sin(self._angle))*self._acceleration)
dx = math.fabs((math.cos(self._angle))*self._acceleration)

# ...


Of course this isn't all, the method still needs to check the heading and decide if the Δx and Δy are positive or negative. With that piece of information the acceleration can be applied properly and to the right direction. The main thing is that it looks good to me right now.

Particle effects!

It gets pretty old pretty soon, moving a simple Shape. So I worked on a Star Control (or Auts or V-Wing or Wings) style acceleration effect. Without spending more than a few seconds on thinking where the engines would be located, I just marked* the bottom edges of the triangle shape as the engine points. Now whenever the acceleration is triggered, a set of tiny box Shapes are dropped at the current coordinates. These Shapes fade away slowly and die away after a few cycles. While I was playing with that I made a silly warping method, where the polygon is relocated in the middle of the game area. At the previous coordinates a set of eight particles are created with speeds set so that it looks like an explosion. It's a funny effect even if I say so myself. That was going to be used to do explosions in the game for real, not teleporting 8)

*) I was farsighted this time. The initial version just takes a set of coordinates for the engine exhaust points, as many as I want, so I can do however I want later. More or less. Perhaps this helps me avoid a couple of rounds of "refactoring because stupid".

Adding some friends on the screen

All in all, what do you do with an almost triangle shaped thingamagick on a 2d space if it's there alone? You'd get bored out of your skull pretty quickly, I tell you. So my possibly retarded idea should be clear to everyone: I'm going to dump in some asteroids! 

I was pretty excited when I got my eight-pointed semirandom shapes on the screen in four different sizes, spinning slowly around either clock- or counterclockwise and after a couple of iterations they even flew through the screen on their merry ways. That was an awesome moment.

Swoosh!
At least I was damn proud of that.

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