Problem with minus and add, causing collision check to fail completely!

[LemonWizard]

Okay I have an issue.
The issue is this.

Before you read the rest it's simple.
I have collision working but, when I add the -1 and +1 operands to account for ONE SINGLE EXTRA PIXEL, the ENTIRE collision check fails.
AND stops player movement to the right side in the CURRENT engine. Continue reading below for full explanation.
I don't understand WHY , the -1 and +1 operands on the collision check are BREAKING the collision at all... It's confusing me! >.<
The reason is because I did the exact same thing before in my other program and it worked. It should work here to!

I'm using the same collision checking routine I used in one of my older engines, for my new sidescroller engine.

So far, there's an issue with tile collision, and I'm doing tile collision manually simply because, well I can.

The problem has to do with a difference between these two snippets.
THIS works:

Code Select Expand


if playerx2 >checkingx1
if playerx2 <checkingx2
if playery2 >checkingy1
if playery1 <checkingy2
moveright=false
else
moveright=true
endif
endif
endif
endif



and THIS does not work:

PlayBASIC Code: [Select]

if playerx2 >checkingx1-1
                     if playerx2 <checkingx2+1
                        if playery2 >checkingy1-1
                           if playery1 <checkingy2+1
                              moveright=false
                           else
                              moveright=true   
                           endif
                        endif
                     endif
                  endif

I have no idea why but if anyone can figure it out that would be great.
My other project uses the same one pixel bias for checking collision and works just fine only it doesn't use tiles.
Please help!! >.<
What I want to do is check the collision between the player and a tile, minus one pixel from the tiles sides, and top/bottom that way the tile itself, doesn't allow the player to move INTO it. Rather. the player is directly against it.

Oh yes.. the old checking routines here did work in my OLD engine which is NOT the same as this engine at all in any way. But. It uses stored platforms and takes their x1, y1, x2, y2 value against the players x1, y1, x2, y2 values. Here is the collision checking routine for my OLD project.

PlayBASIC Code: [Select]

for temp=1 to index
X1=platforms(temp,1 )
Y1=platforms(temp,2 )
X2=platforms(temp,3 )
Y2=platforms(temp,4 )
Px=Object1X
Py=Object1Y
Px2=Object1Y2
Py2=Object1Y2

;reset values just in case
Px2=Px+32
Py2=Py+32

;check collisions

;if were on the first loop
   ;make the player fall by 1
      ;only if landed=false
      
      if landed=false and temp=1
         if bouncing=false
         object1y=object1y+1
   endif
endif

if bouncing=true and temp=1
   object1y=object1y-1
   bouncetime=bouncetime-1
endif



if bouncetime <=0 and temp=1
   bouncing=false
   bouncetime=0
   endif         
         



;check left collision (Player is here --> ||Colliding with LEFT wall of object)
if Px2 >X1-1
   if Px2 <X1+1
      if Py2 >Y1-1
         If Py <Y2+1
            moveright=false
         else
            moveright=true   
      endif      
   endif   
endif
endif

;check right collisions (Colliding with RIGHT wall of object || <--Player is here)
if Px >X2-1
   if Px <X2+1
      if Py2 >Y1-1
         If Py <Y2+1
            moveleft=false
         else
            moveleft=true
      endif      
   endif   
endif   
endif      
;(1 pixel difference between player's Y2 position and the wall's Y1 position!)

;                                                               Player is here
;                                                                  |
;                                                                  |
;                                                                  V   
;check the top collisions (Colliding with TOP wall of object;; |--------| <==Wall
;                                                               |Platform|
;                                                               |         |
;                                                               |--------|
if Px2 >X1-1
   If Px <X2+1
      if Py2 >Y1-5
         If Py2 <Y1+1
            checklanded=true         ;check landed means we have to set landed to true
         endif                        ;after we exit the for-temp loop
      endif                           ;if landed=true the player's Y isn't -1
   endif                              ;repeatedly!That's what makes the player fall
endif                                 ; ( If landed=false then object1y=object1y-1)
                        


;check the bottom collisions (Colliding with the TIP wall of object;;

if Px2 >X1
   If Px <X2
      if Py <Y2+5
         if Py2 >Y2+1
            falling=true
            bouncing=false
            bouncetime=0
         endif
      endif
   endif
   endif         



boxc platforms(temp, 1), platforms(temp, 2), platforms(temp, 3), platforms(temp, 4), 0, rgb(255, 0, 0)

next temp

AND Here is the whole code below for the current engine.

PlayBASIC Code: [Select]

; PROJECT : Castle Crush
; AUTHOR  : NA
; CREATED : 12/27/2011
; EDITED  : 12/31/2011
; ---------------------------------------------------------------------
castle=loadnewfximage("castlecrush.png")
mode=loadnewfximage("mode.png")
HEIGHT=getimageheight(castle)
WIDTH=getimagewidth(castle)
save=loadnewfximage("save.png")


SCROLLX=0
SCROLLY=0
MAPWIDTH=roundup(WIDTH/16)
MAPHEIGHT=roundup(HEIGHT/16)
dim map(MAPWIDTH, MAPHEIGHT)

type solid_tile
   x1
   y1
   x2
   y2
endtype
   

dim solids(MAPWIDTH, MAPHEIGHT) as solid_tile

myimage=newfximage(640, 480)
MODE$="View"


rendertoimage castle

for tempx=1 to WIDTH/16
   for tempy=1 to HEIGHT/16
      ink rgb(255,255, 255)
      box (tempx-1)*16, (tempy-1)*16, tempx*16, tempy*16, 0
   next tempy
   next tempx   
      

charx=200
chary=0
falling=false


do

if enterkey()
   falling=true
endif
   

;draw map 


;render to the map image
rendertoscreen


         
rendertoimage castle

x=mousex()
y=mousey()

if SCROLLX=>16
   amountx=roundup(SCROLLX/16)
   else amountx=1
endif
   ;top side same thing as above
if SCROLLY=>16
   amounty=roundup(SCROLLY/16)
else
   amounty=1
endif





if charx=>16
   checkcharx=roundup(charx/16)
   else checkcharx=1
endif
   ;top side same thing as above
if chary=>16
   checkchary=roundup(chary/16)
else
   checkchary=1
endif



      


for tempx=amountx to 32  ;disable x scroll for this entirely for the right side
   for tempy=amounty to 30+amounty
      
      x=(tempx-1)*16
      y=(tempy-1)*16
      
      xdraw=x-SCROLLX
      ydraw=y-SCROLLY
      ink rgb(0, 255, 0)
      box x, y, x+16, y+16, 0
            
            ;check solid tiles below character
            
            
            
            ;check player on tile
                  
                  if map(tempx, tempy)=1       ;if the tile is solid, check against player collision         
                     
                     
               checkingx1=solids(tempx, tempy).x1
               checkingy1=solids(tempx, tempy).y1
               checkingx2=solids(tempx, tempy).x2
               checkingy2=solids(tempx, tempy).y2
               
               
                           
                           playerx1=charx
                           playery1=chary
                           playerx2=charx+16
                           playery2=chary+16
                           
                           if playerx2>checkingx1         ;the players x coordinates align
                              if playerx1<=checkingx2
                              
                              if playery2=>checkingy1         ;the player is ontop of the platform or past it
                                    if playery1<=checkingy1 ;the players top edge is not past the top of the platform
                                       landed=true
                                    endif
                                 endif
                              endif
                           endif
                                       
                                 
                           
                              ;check for left and right sides
                  ;check left collision (Player is here --> ||Colliding with LEFT wall of object)


                  if playerx2 >checkingx1-1
                     if playerx2 <checkingx2+1

Login required to view complete source code

[LemonWizard]

Omg I solved it with this bunch:

PlayBASIC Code: [Select]

if map(tempx, tempy)=1       ;if the tile is solid, check against player collision         
                     
                     
               checkingx1=solids(tempx, tempy).x1
               checkingy1=solids(tempx, tempy).y1
               checkingx2=solids(tempx, tempy).x2
               checkingy2=solids(tempx, tempy).y2
               
               
                           
                           playerx1=charx
                           playery1=chary
                           playerx2=charx+16
                           playery2=chary+16
                           
                           if playerx2>checkingx1         ;the players x coordinates align
                           if playerx1<checkingx2                  
                                    if playery1<checkingy1 ;the players top edge is not past the top of the platform
                                 if playery2>checkingy1-1 ;the players bottom edge IS past the top of the platform-1 pixel
                                       landed=true
                                    endif
                                 endif
                           endif
                        endif
                              
                                       
                                 
                           
                              ;check for left and right sides
                  ;check left collision (Player is here --> ||Colliding with LEFT wall of object)

                                             
                     if playerx2>checkingx1-1
                        if playerx2<checkingx1+1
                           if playery2>checkingy1
                              if playery1<checkingy2
                                 moveright=false
                              else
                                 moveright=true
                              endif
                           endif
                        endif
                     endif
                                    
                                    ;check right collision
                     if playerx1>checkingx2-1
                        if playerx1<checkingx2+1
                           if playery2>checkingy1
                              if playery1<checkingy2
                                 moveleft=false
                              else
                                 moveleft=true
                              endif
                           endif
                        endif
                     endif
                                    
                     
                           
                           
                           
                           
                     endif