Gravlab II

leofox · Post by **leofox** » Thu 21 Sep, 2006 9:45 pm

Gravlab was a little test program i made in TI-basic, a demo of a falling and bouncing ball. For my senior assignment (or w/e you call that in English), i decided to remake it in ASM/Basic.
In essence, it's now a physically accurate simulation of a ball falling in vacuum. Features i plan to add are multiple objects, friction, realistic collision , shooting the ball (giving it a certain start velocity) and maybe even wind.
I don't plan to use it in a game, it's main purpose is demonstration in physics class, clarifying gravity. Similar programs are already used in physics class, but usually the teacher does the settings and the students only watch. Gravlab II would allow every student to figure it out by themself.

Basic/ASM means that the main menu and user input is written in TI Basic, but the actual graphical simulation (where accuracy and speed are so very much needed) is 100% Assembly without any rom calls in the main loop.

Sorry if it sounds vague atm, more will follow later including screenies. It WILL be finished before january 2007, with extensive documentation. It's a school project after all

My first calc project i post on MC before UTI.. *sigh*

Post by **DarkAuron** » Thu 21 Sep, 2006 10:30 pm

Sounds great! Maybe you should allow addition of wall objects or what not that it could bounce off, or even roll down?

King Harold · Post by **King Harold** » Fri 22 Sep, 2006 8:12 am

yes sounds great, are you going to add spinning and spinning-friction aswell?
the last one might be little hard though, but very cool.

leofox · Post by **leofox** » Fri 22 Sep, 2006 1:41 pm

DarkAuron wrote:Sounds great! Maybe you should allow addition of wall objects or what not that it could bounce off, or even roll down?

Walls would be easy, slopes are not planned currently.

CoBB · Post by **CoBB** » Fri 22 Sep, 2006 2:10 pm

Implementing proper collision can be a major pain.

leofox · Post by **leofox** » Fri 22 Sep, 2006 3:11 pm

Yeah, that would be the hardest part probably. Luckily i have the help of a computer science and physics teacher.

leofox · Post by **leofox** » Sat 23 Sep, 2006 9:28 pm

a screenie for the masses!

Values here are acceleration of $00,$00,$01 and frameskip of $80.
In human, that means the acceleration is 1/65536th of a pixel, but it only draws one in 128 frames (so it runs at a decent speed). It's kinda jumpy now, but that's because most of the speed is spent on calculating. Higher acceleration is recommended, so you can lower the frameskip for a smoother picture. You lose a bit of accuracy though, but that shouldn't matter because the speed barely goes above 1pixel anyway (the problem with these is that if your speed is too high, objects will fall through each other).

CoBB · Post by **CoBB** » Sat 23 Sep, 2006 11:05 pm

leofox wrote:(the problem with these is that if your speed is too high, objects will fall through each other).

That's exactly the kind of problem I was thinking about.

Jim e · Post by **Jim e** » Sat 23 Sep, 2006 11:58 pm

Yeah I've had that problem, its really annoying.

leofox · Post by **leofox** » Sun 24 Sep, 2006 12:04 pm

CoBB wrote:
leofox wrote:(the problem with these is that if your speed is too high, objects will fall through each other).
That's exactly the kind of problem I was thinking about.

The floor is now only pixel high ( i just check cp 60 -_-') but i'm not running into problems yet. That's where frameskip is for

leofox · Post by **leofox** » Thu 09 Nov, 2006 9:38 pm

I am now adding friction (gaah... it needs division and multiplication, which is a bitch to do with 3 byte numbers :S ) and a way to control the ball with the keypad in real time. It'd be pretty cool, the first step to maybe implementation in a game.

Timendus · Post by **Timendus** » Thu 09 Nov, 2006 9:50 pm

The API has a 16 bit multiplication routine under Mathematics, perhaps it can help you get inspiration..?

leofox · Post by **leofox** » Fri 10 Nov, 2006 9:56 am

Thanks, i'll look at that.

anykey · Post by **anykey** » Sun 12 Nov, 2006 1:06 am

ooooh...me gusta gravity.

nepmarauder · Post by **nepmarauder** » Sun 12 Nov, 2006 5:54 pm

I was thinking about making a program like this. But, I never have much time to program. I'd like to see this when its finished. Good luck.