..this is something I deal with and working fine..smooth jump up and going down smoth too, just put in main loop..pivott is pivot of your entity, camera, whatever..
;Jump Parameters,somewhere at begin of proggy
Global Jump_Height#=0.1
Global Drop_Speed#=0.05
;put this somewhere as Update_Jump() function and call it from main loop
If KeyHit(57) And jumping = 0 Then yvelocity# = 15 jumping = 1
CountCollisions (pivott)
If EntityCollided(pivott,2)
If CollisionNY#(pivott,1)<>0
If yvelocity#<0 Then jumping=0
yvelocity#=yvelocity#*Jump_Height#
EndIf
EndIf
yvelocity#=yvelocity#-Drop_Speed#
MoveEntity pivott,speedx,yvelocity#,speedz#
;========================================================
;Jump Parameters,somewhere at begin of proggy
Global Jump_Height#=0.1
Global Drop_Speed#=0.05
;put this somewhere as Update_Jump() function and call it from main loop
If KeyHit(57) And jumping = 0 Then yvelocity# = 15 jumping = 1
CountCollisions (pivott)
If EntityCollided(pivott,2)
If CollisionNY#(pivott,1)<>0
If yvelocity#<0 Then jumping=0
yvelocity#=yvelocity#*Jump_Height#
EndIf
EndIf
yvelocity#=yvelocity#-Drop_Speed#
MoveEntity pivott,speedx,yvelocity#,speedz#
;========================================================