help me? how do i get it to stay on the platform that is visible?

[babacaba]

% credits to the original jump program
% some constants, tweak this to your liking
var GROUND_HEIGHT := 180
var GROUND_2 := 120
var GROUND := 1
const invisline:= 150
const RUN_SPEED := 5
const JUMP_SPEED := 20
const GRAVITY := 2

var win := Window.Open ("graphics:640;480,offscreenonly")
var chars : array char of boolean

% player position and velocity
var posx, posy : int
var velx, vely : real

posx := 20
velx := 0
posy := 120
vely := 0

loop
Input.KeyDown (chars)
if chars ('q') then
exit
end if

% to make the player move
if chars (KEY_LEFT_ARROW) then
velx := -RUN_SPEED
elsif chars (KEY_RIGHT_ARROW) then
velx := RUN_SPEED
else
velx := 0
end if

% remember, in order to jump you MUST be on the ground when pressing UP
if chars (KEY_UP_ARROW) and posy = GROUND_HEIGHT or posy = GROUND_2 then
vely := JUMP_SPEED
end if

% subtract your "gravity" constant from the velocity EACH frame
vely -= GRAVITY
posx += round (velx)
posy += round (vely)

% simple "collision" check. just makes sure the player stays above ground
if posy < GROUND_2 then
posy := GROUND_2
vely := 0
end if
if posy = invisline then
posy := GROUND_HEIGHT
vely := 0
end if





% different colours just to illustrate whether or not you may jump
if posy = GROUND_HEIGHT then
drawfillbox (posx - 10, posy, posx + 10, posy + 20, red)
else
drawfillbox (posx - 10, posy, posx + 10, posy + 20, green)
end if

if posy = GROUND_2 then
drawfillbox (posx - 10, posy, posx + 10, posy + 20, red)
else
drawfillbox (posx - 10, posy, posx + 10, posy + 20, green)
end if


drawline (100, GROUND_HEIGHT, 200, GROUND_HEIGHT, blue)

if posy = GROUND then
drawfillbox (posx - 10, posy, posx + 10, posy + 20, red)
else
drawfillbox (posx - 10, posy, posx + 10, posy + 20, green)
end if
drawline (0, 0, maxx, 0, red)
drawline (0, GROUND_2, 100, GROUND_2, blue)
drawline (0,invisline,maxx,invisline, white)
View.Update
delay (25)
cls
end loop
put "YOU LOSE!!!!!"
delay (999999999)

Window.Close (win)







what am i doing wrong?
what havnt i done?

[ecookman]

i am not quite sure on how you did this, but the simplest way i can see to do this is color each of the boxes and then create a collision using colors, but if you are determined to keep it this way I'm sure there are some tutorials in the help section.


I know how to set up collisions in VB6 but not quite sure about Turing...if someone with some knowledge knows if they are similar please let me know, then i will be happy to help you out with your collision problem. (but i think you need ot set a range of where the floor is not the one pixel)