Here's a quick code sample off the top of my head:
That should give you a basic idea :)
Const GRAVITY# = 0.005 Local PlayerYVel# = 0 ;Players vertical velocity Local PlayerYPos# = 0 ;Players vertical position Repeat ;Begin looping ;Deduct gravity from the players vertical velocity. PlayerYVel# = PlayerYVel# - GRAVITY# ;If the player is touching the ground, set vertical velocity ;to 0 (since upward force from the ground would equal ;downward force from gravity). If (PlayerIsOnGround) then PlayerYVel# = 0.0 ;If the player jumps, set the vertical velocity to a positive value. If (PlayerJumps) then PlayerYVel# = 5.0 ;Adjust the player vertical position based on the vertical velocity. PlayerYPos# = PlayerYPos# + PlayerYVel# Until KeyHit( 1 );End loop
That should give you a basic idea :)