Computer Science Canada

Need Help with Collision
Author:  18729 [ Mon Sep 25, 2006 9:43 pm ]
Post subject:  Need Help with Collision
can someone help me with my collision in my asteroids game. the rocks explode even when its not touching the ship. it explodes a few pixels away only on the left side thouhg....not on the right
code:

setscreen ("graphics:640;480,nocursor")
var shippic : int := Pic.FileNew ("Spaceship.bmp")
var rock1pic : int := Pic.FileNew ("Rock1.bmp")
var rock2pic : int := Pic.FileNew ("Rock2.bmp")
var rock3pic : int := Pic.FileNew ("Rock3.bmp")
var rock4pic : int := Pic.FileNew("Rock4.bmp")
var rock5pic : int := Pic.FileNew("Rock5.bmp")
var boompic : int := Pic.FileNew("Boom.bmp")
var laserpic : int := Pic.FileNew ("Laser.bmp")
var shipxcenter : int := 290
var shipycenter : int := 0
var rock1xcenter : int := Rand.Int (10, 630)
var rock1ycenter : int := maxy + 20
var rock2xcenter : int := Rand.Int (10, 630)
var rock2ycenter : int := maxy + 20
var rock3xcenter : int := Rand.Int (10, 630)
var rock3ycenter : int := maxy + 20
var rock4xcenter : int := Rand.Int (10,630)
var rock4ycenter : int := maxy + 20
var rock5xcenter : int := Rand.Int (10,630)
var rock5ycenter : int := maxy + 20
var boomxcenter : int := 0
var boomycenter : int := 0
var laserxcenter : int :=-10
var laserycenter : int :=-10
var shoot: boolean :=false
var chars : array char of boolean
var key : string(1):=""
var speedofship : int := 10
var font1 : int := Font.New ("comicsans:12")
var score : int := 0
var lives : int := 3
procedure DrawShip (x, y : int)
    Pic.Draw (shippic, x, y, picMerge)
end DrawShip
procedure DrawRock (x, y ,rockpic: int)
    Pic.Draw (rockpic, x, y, picMerge)
end DrawRock
procedure DrawBoom(x,y :int)
    Pic.Draw(boompic,x,y,picMerge)
    end DrawBoom
procedure DrawLaser (x, y : int)
    Pic.Draw (laserpic, x, y, picMerge)
end DrawLaser
 DrawShip (shipxcenter, shipycenter)
 procedure Collision(X1:int,Y1:int,var X2:int,var Y2:int,pic1:int,pic2:int)
  if X1+Pic.Width(pic1)/2>X2-Pic.Width(pic2)/2 and X1-Pic.Width(pic1)/2<X2+Pic.Width(pic2)/2 and Y1+Pic.Width(pic1)>Y2-Pic.Width(pic2)/2 and Y1-Pic.Width(pic1)/2<Y2+Pic.Width(pic2)/2 then
  boomxcenter:=X2
   boomycenter:=Y2
   DrawBoom(boomxcenter,boomycenter)
X2  := Rand.Int (10,630)
Y2  := maxy + 20
     lives:=lives-1
    end if
    end Collision
 loop
 Input.KeyDown (chars)
    View.Update
    View.Set ("offscreenonly")
    cls
    Font.Draw ("Score: ", 10, 465, font1, 7)
    Font.Draw (intstr (score), 70, 465, font1, 7)
    Font.Draw ("Lives: ", 500, 465, font1, 7)
    Font.Draw (intstr (lives), 560, 465, font1, 7)
    if hasch then
    getch(key)
 end if
  if shoot=true then
    laserycenter:=laserycenter+20
 end if
     if chars (chr(ORD_SPACE)) and laserxcenter=-10 and laserycenter=-10 then
     laserxcenter:=shipxcenter+27
    laserycenter:=shipycenter+97 
    shoot:=true
    end if
    DrawLaser(laserxcenter,laserycenter)
   if laserycenter>=maxy+10 then
   laserxcenter:=-10
   laserycenter:=-10
   shoot:=false
   end if
    if chars (KEY_UP_ARROW) then
        shipycenter := shipycenter + speedofship
    end if
    if chars (KEY_RIGHT_ARROW) then
        shipxcenter := shipxcenter + speedofship
    end if
    if chars (KEY_LEFT_ARROW) then
        shipxcenter := shipxcenter - speedofship
    end if
    if chars (KEY_DOWN_ARROW) then
        shipycenter := shipycenter - speedofship
    end if
    DrawShip (shipxcenter, shipycenter)
    if shipxcenter <= 1 then
        shipxcenter := 1
    end if
    if shipxcenter >= maxx - Pic.Width (shippic) then
        shipxcenter := maxx - Pic.Width (shippic)
    end if
    if shipycenter <= 1 then
        shipycenter := 1
    end if
    if shipycenter >= maxy - Pic.Height (shippic) then
        shipycenter := maxy - Pic.Height (shippic)
    end if
    DrawRock (rock1xcenter, rock1ycenter,rock1pic)
    rock1ycenter := rock1ycenter - 1
    if rock1ycenter <= 0 then
        rock1xcenter := Rand.Int (10, 630)
        rock1ycenter := maxy + 20
    end if
    DrawRock (rock2xcenter, rock2ycenter,rock2pic)
    rock2ycenter := rock2ycenter - 2
    if rock2ycenter <= 0 then
        rock2xcenter := Rand.Int (10, 630)
        rock2ycenter := maxy + 20
    end if
    DrawRock (rock3xcenter, rock3ycenter,rock3pic)
    rock3ycenter := rock3ycenter - 3
    if rock3ycenter <= 0 then
        rock3xcenter := Rand.Int (10, 630)
        rock3ycenter := maxy + 20
    end if
      DrawRock (rock4xcenter, rock4ycenter,rock4pic)
    rock4ycenter := rock4ycenter - 4
    if rock4ycenter <= 0 then
        rock4xcenter := Rand.Int (10, 630)
        rock4ycenter := maxy + 20
    end if
      DrawRock (rock5xcenter, rock5ycenter,rock5pic)
    rock5ycenter := rock5ycenter - 5
    if rock5ycenter <= 0 then
        rock5xcenter := Rand.Int (10, 630)
        rock5ycenter := maxy + 20
    end if
   Collision(shipxcenter,shipycenter,rock1xcenter,rock1ycenter,shippic,rock1pic)
   Collision(shipxcenter,shipycenter,rock2xcenter,rock2ycenter,shippic,rock2pic)
   Collision(shipxcenter,shipycenter,rock3xcenter,rock3ycenter,shippic,rock3pic)
   Collision(shipxcenter,shipycenter,rock4xcenter,rock4ycenter,shippic,rock4pic)
   Collision(shipxcenter,shipycenter,rock5xcenter,rock5ycenter,shippic,rock5pic)
    if laserxcenter+Pic.Width(laserpic)/2>rock1xcenter-Pic.Width(rock1pic)/2 and laserxcenter-Pic.Width(laserpic)/2<rock1xcenter+Pic.Width(rock1pic)/2 and laserycenter+Pic.Width(laserpic)>rock1ycenter-Pic.Width(rock1pic)/2 and laserycenter-Pic.Width(laserpic)/2<rock1ycenter+Pic.Width(rock1pic)/2 then
       boomxcenter:=rock1xcenter
       boomycenter:=rock1ycenter
    DrawBoom(boomxcenter,boomycenter)
       rock1xcenter := Rand.Int (10, 630)
        rock1ycenter := maxy + 20
    score:=score+1
    end if
    if laserxcenter+Pic.Width(laserpic)/2>rock2xcenter-Pic.Width(rock2pic)/2 and laserxcenter-Pic.Width(laserpic)/2<rock2xcenter+Pic.Width(rock2pic)/2 and laserycenter+Pic.Width(laserpic)>rock2ycenter-Pic.Width(rock2pic)/2 and laserycenter-Pic.Width(laserpic)/2<rock2ycenter+Pic.Width(rock2pic)/2 then
       boomxcenter:=rock2xcenter
       boomycenter:=rock2ycenter
    DrawBoom(boomxcenter,boomycenter)
       rock2xcenter := Rand.Int (10, 630)
        rock2ycenter := maxy + 20
    score:=score+1
    end if
    if laserxcenter+Pic.Width(laserpic)/2>rock3xcenter-Pic.Width(rock3pic)/2 and laserxcenter-Pic.Width(laserpic)/2<rock3xcenter+Pic.Width(rock3pic)/2 and laserycenter+Pic.Width(laserpic)>rock3ycenter-Pic.Width(rock3pic)/2 and laserycenter-Pic.Width(laserpic)/2<rock3ycenter+Pic.Width(rock3pic)/2 then
       boomxcenter:=rock3xcenter
       boomycenter:=rock3ycenter
    DrawBoom(boomxcenter,boomycenter)
       rock3xcenter := Rand.Int (10, 630)
        rock3ycenter := maxy + 20
    score:=score+1
    end if
    if laserxcenter+Pic.Width(laserpic)/2>rock4xcenter-Pic.Width(rock4pic)/2 and laserxcenter-Pic.Width(laserpic)/2<rock4xcenter+Pic.Width(rock4pic)/2 and laserycenter+Pic.Width(laserpic)>rock4ycenter-Pic.Width(rock4pic)/2 and laserycenter-Pic.Width(laserpic)/2<rock4ycenter+Pic.Width(rock4pic)/2 then
       boomxcenter:=rock4xcenter
       boomycenter:=rock4ycenter
    DrawBoom(boomxcenter,boomycenter)
       rock4xcenter := Rand.Int (10, 630)
        rock4ycenter := maxy + 20
    score:=score+1
    end if
    if laserxcenter+Pic.Width(laserpic)/2>rock5xcenter-Pic.Width(rock5pic)/2 and laserxcenter-Pic.Width(laserpic)/2<rock5xcenter+Pic.Width(rock5pic)/2 and laserycenter+Pic.Width(laserpic)>rock5ycenter-Pic.Width(rock5pic)/2 and laserycenter-Pic.Width(laserpic)/2<rock5ycenter+Pic.Width(rock5pic)/2 then
       boomxcenter:=rock5xcenter
       boomycenter:=rock5ycenter
    DrawBoom(boomxcenter,boomycenter)
       rock5xcenter := Rand.Int (10, 630)
        rock5ycenter := maxy + 20
    score:=score+1
    end if
    exit when lives=0 or score=20
    end loop
    cls
    if lives<=0 then
Font.Draw ("Game Over! ", 320, 240, font1, 7)
elsif score>=20 then
Font.Draw ("You Win! ", 320, 240, font1, 7)
end if
Author:  Silent Avenger [ Mon Sep 25, 2006 9:53 pm ]
Post subject: 
Well here's a link to an example lower down on the list. There should be some code in there. I'm not sure if this is what you're looking for but I hope it helps.

Link: http://www.compsci.ca/v2/viewtopic.php?t=13379
Author:  TokenHerbz [ Tue Sep 26, 2006 1:30 am ]
Post subject: 
Alright, befor we go to your prblem, you should try to minimize all that reapeated code you have, make it much nicer, and understandable.

i cant follow your flawd math to help solve this right now, as you have

var shipxcenter : int := 290 (that really the center of your ship? or your x chords for the ship)

anyways, i think you problem lies in the start of the collide codes as they all are: laserxcenter+Pic.Width(laserpic)/2, note that "+"... i think that should be a "-" on say, collition with the left/bottom?

I really cant understand your coding, and the lack of comments don't help me at all...

**tears** i tried?
Author:  TheOneTrueGod [ Tue Sep 26, 2006 8:19 am ]
Post subject: 
Ya, this is most probably a calculation error. One way that I try to use when debugging square-based collision is to ONLY write the up/down collision, and then test it. Once I have done this, then I comment it out, and ONLY write the left/right collision, and test that. Once I have that working, I uncomment up/down collision, and test the two together. All should go smoothly Razz.
Author:  BenLi [ Thu Sep 28, 2006 6:32 pm ]
Post subject: 
several things that might make your life easier:

- get rid of picMErge if possible (it slows you down crop picture?)
-
code:
if chars (chr(ORD_SPACE))

is the same as
code:
if chars (' ')


-
code:
var rock1xcenter : int := Rand.Int (10, 630)
var rock1ycenter : int := maxy + 20
var rock2xcenter : int := Rand.Int (10, 630)
var rock2ycenter : int := maxy + 20
var rock3xcenter : int := Rand.Int (10, 630)
var rock3ycenter : int := maxy + 20
var rock4xcenter : int := Rand.Int (10,630)
var rock4ycenter : int := maxy + 20
var rock5xcenter : int := Rand.Int (10,630)
var rock5ycenter : int := maxy + 20


this is fairly repetitive. Use arrays for something like this

code:

var rockxcenter : array 1..5 of int
var rockycenter : array 1..5 of int
for i:1..5
rockxcenter (i):= Rand.Int (10,630)
rockycenter (i):= maxy + 20
end for


same with your rock pictures

also, i noticed several silmilar procedures

code:

procedure DrawShip (x, y : int)
    Pic.Draw (shippic, x, y, picMerge)
end DrawShip
procedure DrawRock (x, y ,rockpic: int)
    Pic.Draw (rockpic, x, y, picMerge)
end DrawRock
procedure DrawBoom(x,y :int)
    Pic.Draw(boompic,x,y,picMerge)
    end DrawBoom
procedure DrawLaser (x, y : int)
    Pic.Draw (laserpic, x, y, picMerge)
end DrawLaser


it should be

code:

proc drawstuff (x,y,pic:int)
    Pic.Draw (laserpic, x, y, picMerge)
end drawstuff


and to use the array:
code:
   Collision(shipxcenter,shipycenter,rock1xcenter,rock1ycenter,shippic,rock1pic)
   Collision(shipxcenter,shipycenter,rock2xcenter,rock2ycenter,shippic,rock2pic)
   Collision(shipxcenter,shipycenter,rock3xcenter,rock3ycenter,shippic,rock3pic)
   Collision(shipxcenter,shipycenter,rock4xcenter,rock4ycenter,shippic,rock4pic)
   Collision(shipxcenter,shipycenter,rock5xcenter,rock5ycenter,shippic,rock5pic)


code:

    for i:1..5
       Collision(shipxcenter,shipycenter,rockxcenter(i),rockycenter(i),shippic,rockpic (i))
       end for


Good job, these are very minor stuff that you'll easily be able to fix up. Anyways, these are just efficiency things, pretty minor.

If you want help you should post the pictures you are using

:


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