Variable Jump??

I think the way games like mario did it is to not allow gravity to work until you let go of jump (up to a certain limit). That means the speed will be constant up until the jump button is released, which makes the height jumped fairly proportional to the amount of time pressed, plus it keeps the jumps consistently parabolic (except while jump is being held). In pseudo-code, if(jumpIsPressed && pressedTime < (.3 * seconds) ) ySpeed = 32;

[edited by - timbatron on November 22, 2003 9:53:10 PM]

yeh or you could even make the speed increase as you hold it up to a limit

Well, that is not natural since the speed is at maximum at the point of escaping gravity.

One way to do it is this (pseudocode)

#define X your jump velocity

float JumpVelocity = X;

if ( jumpKeyPressed && JumpVelocity > 0 )
{
JumpVelocity -= your gravity constant ;
}
else if ( jumpKeyReleased )
{
JumpVelocity = 0;
}

Do your physics here

if( JumpVelocity == 0 )
{
JumpVelocity = X;
}

Thanks you all.
I''m using RhoneRanger solution for the moment, and it is working great. I think it is more realistic than the others, though realism isn''t most important thing in platforms game, but also it does not require a counter to check how much time key has been pressed.

Anyway I find Timbatron'' solution really good for this kind of application