How To Make People Jump

omni · Member Joined: 14 Jun 2003 Posts: 115

In the side scrollers like Mario, how do you get the guy to jump and make him fall down again in z80? I know how to move it right and left, but not up and down.
I don't need any source code, just the concepts and ideas needed to construct the code.

DarkerLine · Posted: 13 Nov 2003 05:21:29 pm Post subject:

You mean how to find the coordinates at a given time, not how to display the sprite? I believe it's quadratic.

omni · Member Joined: 14 Jun 2003 Posts: 115

Both and whats quadratic? We haven't got that far in school. (Schools in North America stink in math compared to China. In grade 10 BTW)

interwined · Newbie Joined: 26 Sep 2003 Posts: 39

Information about the quadratic formula can be found http://mathworld.wolfram.com/QuadraticEquation.html. We learned about that in seventh grade and I live in Ohio.

JacobdeHaan · Member Joined: 10 Jul 2003 Posts: 165

Sir Robin's idea would probably work the best.
A negative quadratic function will give you the sort of shape you would like for the jump (if you want to see this, just type in -xx in y= and press graph)
So you would just plug in the x coordinate to get your y coordinate and you've got your sprite's location.
BTW, what math are you in?

DigiTan · Posted: 13 Nov 2003 07:54:58 pm Post subject:

Quadratic equations are usefull for plotting paths for falling objects (such as a jumping plumber or a leaping hedgehog). The purpose here is to avoid those unnatural-looking jumps where your character leaps up at a constant speed, and then immidiately falls down at the same constant speed.

Instead, as your character jumps, his upward speed should slow until he reaches a peak height. Then naturally, 'gravity' pulls him downward in a similar fashion--causing him to fall faster and faster until he hits the ground again.

Whenever gravity is involved you'd use the quadratic:

Darth Android · Posted: 13 Nov 2003 11:56:02 pm Post subject:

learned quadratic formula in 7th grade. i live in texas.

NETWizz · Posted: 13 Nov 2003 11:57:45 pm Post subject:

I think that is the normal time to learn it. Am I wrong?

DigiTan · Posted: 14 Nov 2003 01:53:56 am Post subject:

Yeah, we studied quadratics in 7th grade in Austin, Tx. I think they called them "polynomials" at the time (while learning "F.O.I.L." and such). Although, I didn't ever use the gravity formula until we decided to build a potato launcher in high school.

omni · Member Joined: 14 Jun 2003 Posts: 115

JacobdeHaan
I am in Canada, Ontario. They have not taught quadratics yet. They teach it in grade 10, like some time in January. I am currently in grade 10.
Man U.S. math is awesome compared to Canadian. Stupid education board!! Mad

In canada they first introduce polynomials in grade 7 and 8.
ex :
simplify 2x+4x=6x
In grade 9 thats when they teach factoring and the such
ex:
simplify (a+ B ) (a+ B ) = a^2+2ab+b^2

DarkerLine · Posted: 14 Nov 2003 03:58:13 pm Post subject:

I learned quadratics in 7th grade but I've been trying hard to get ahead in math so I am at the same level as my friends in Russia (some of my friends are now learning them in 10th grade). I am currently in 9th grade in North Carolina.

Aren't quadratics first taught in the 2nd part of Algebra 1?

JacobdeHaan · Member Joined: 10 Jul 2003 Posts: 165

Quadratics are a major part of all of Algebra 1 because it is all about factoring and multiplying polynomials, and using the Quadratic formula.

DigiTan · Posted: 14 Nov 2003 06:49:47 pm Post subject:

Well anyways, you'd want to try a quadratic to get more natural, more true-to-life motion. Though, most TIs have so little picture resolution, an actual quadratic may be overdoing it. You could try streamlineing the process by having the having the character's speed decrease maybe mid-way through the jump. The main thing is to avoid letting the character rise and fall at constant speeds.

omni · Member Joined: 14 Jun 2003 Posts: 115

If I just wanted the character to fall, like if it walked off a small ledge, would i also use quadratics?

sgm · Calc Guru Joined: 04 Sep 2003 Posts: 1265

I think a very rough method that should give okay results would go like:

When the player jumps, give him a starting "force" (number of pixels to go up)
Add his current jump force to his y-position
Each frame, subtract from his jump force some constant value (force of gravity)
Check for hitting his head or landing on a platform

When the force becomes negative, probably should implement a terminal velocity (maximum number of pixels he can fall in one frame).

JacobdeHaan · Member Joined: 10 Jul 2003 Posts: 165

Another thing to factor in when you are making a side scroller is that in many of them, they allow you to move while falling, so really only your Y coordinates should be controlled by it, leaving the X vars in the control of the user.

omni · Member Joined: 14 Jun 2003 Posts: 115

well currently I have an aligned sprite routine, how would you create smooth scrolling?
And which one should I attempt to make first, smooth scrolling or jumping?

MaxVT103 · Member Joined: 24 Aug 2003 Posts: 109

I would definately try to get the smooth scrolling bc that will probobly be one of the most difficult thing you will do. Everything will most likely build off of it.

DigiTan · Posted: 15 Nov 2003 10:58:42 pm Post subject:

omni · Member Joined: 14 Jun 2003 Posts: 115

ah alright, but if my game is just a side scroller I wouldn't need the vertical stuff right?
Digitan could you explain how you got those numbers?

United-TI Archives -> Z80 & 68k Assembly
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