Whatdotcolor collision help

[sierius]

code:

View.Set ("graphics:max;max;offscreenonly;nocursor") const base := 60 const movement := 10 const jump_dis := 25 const gravity := 2 var keyslah : array char of boolean var tcoins : nat := 0 var jumponly := true % player position and velocity var posx := 20 var velx := 0.0 var posy := base var vely := 0.0 loop     cls     Input.KeyDown (keyslah)     % left and right keyt     if keyslah (KEY_LEFT_ARROW) and posx - 10 > 0 then         velx := -movement     elsif keyslah (KEY_RIGHT_ARROW) and posx + 10 < maxx - 10 then         velx := movement     else         velx := 0     end if     %% up key     if keyslah (KEY_UP_ARROW) and jumponly = true then         vely := jump_dis         jumponly := false     end if     % subtract your gravity constant from the velocity     if View.WhatDotColor (posx, posy - 1) not= black then         vely -= gravity         posx += round (velx)         posy += round (vely)     end if     % on the ground ?     if posy < base then         posy := base         vely := 0         jumponly := true     end if     if View.WhatDotColor (posx, posy-1) = black then         vely := 0         vely += gravity         jumponly := true         delay (40)     end if     % change if colors if you can't jump     if jumponly = true then         drawfillbox (posx , posy, posx + 20, posy + 20, green)     else         drawfillbox (posx , posy, posx + 20, posy + 20, 79)     end if     % drawing stuff in the background     Draw.ThickLine (25, 180, 100, 180, 2, black)     Draw.ThickLine(200, 220, 315, 220, 2, black)     Draw.ThickLine(450, 240, 575, 240, 2, black)     Draw.ThickLine(660, 260, 785, 260, 2, black)     drawline (0, base, maxx, base, 64)     %% just so I know where posx and posy are     drawfilloval (posx, posy, 1, 1, 12)     drawbg     level_tut_1     delay (25)     View.Update end loop

This is the code of a platformer game I was trying to create.
I first approached by trying to input if any point on the base posx ... poxs + 20 and and posy -1 was the leveled black line then don't move. but I have 4 platforms so that would be a hassle.

I looked a little into whatdotcolor collision and found it should be able to help me.
But what I no understand is how to make it function. I have set a boolean variable called jumponly so you can only jump once again if you are on a platform or the 'base'

However, the square never halted when its above the platform, instead it falls down.

If anyone could tell me what I am doing wrong it would be appreciated ^^

[DanielG]

doesn't run, missing drawbg and level_tut_i procs

[isaiahk9]

@ DanielG : Just comment it out. Although, you don't actually need to see the program running to help sierius.

@ sierius : Before you draw your square in your loop, you have to go something ike this :

If View.WhatDotColor (posx, posy ) = black then
posy += 5
End If

Off the top of my head, that's it.

PS : I'm pretty sure most of that code can be found in that gravity tutorial in the tutorial section. . .

[TheGuardian001]

major edit here:

ok, having looked over your code again, I know why it doesn't work. at the start of the loop you clear the screen with cls. then check for collisions. then draw the boxes.

since you cleared the screen, it is now completely white. you then check if you've hit a black pixel, which you haven't, because the screen is white, then you draw.

simply switching the order of these things should make it work properly.

[isaiahk9]

TheGaurdian001 makes an excellent point : your amount of pixels you increase in height should equal your gravity decreasing your pixels. But that wasn't his excellent point. it is that : View.WhatDotColor really is not good. I spent hours on my project last year trying to fix failing View.WhatDotColor, and in the end the best choice was to "hard-code" the platforms (make it so that if the user's position is where the platform is, their y variable/x variable increases/decreases). Saving yourself the trouble, in my mind would be avoiding View.WhatDotColor.