pointer on a grid - GameCreators Forum

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shadey

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Posted: 6th Feb 2013 14:04 Edited at: 6th Feb 2013 14:28

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how do i make the x and y coordinates of the pointer stick to a grid so that it moves a 8*4 block at a time,basically in like the one used in AGK's own object placement editor with the grid turned on, thanks for any help

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DVader

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Posted: 6th Feb 2013 18:34

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Simple enough, I do it regularly with editors.

+ Code Snippet

gridx=10
gridy=10
sprite=createsprite(0)
do
x1=floor(getpointerx()/gridx)
y1=floor(getpointery()/gridy)
setspriteposition(sprite,x1*gridx,y1*gridy)
sync()
loop

That will position the sprite at the grid position of the cursor, which is set to 10 x10. You can play with the grid size to get it how you want, add an offset if you do not want it to start at the edge of the screen etc.

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Markus

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Posted: 6th Feb 2013 18:46

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and the same as a function

+ Code Snippet


    x1=Grid(x#,10.0)
    y1=Grid(y#,10.0)

function Grid(v#,grid#)

    v#=floor(v#/grid#)*grid#

endfunction v#

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Marl

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Posted: 6th Feb 2013 23:26

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Quote: "...a 8*4 block ..."

If the size is fixed and a power of 2, you could use a short cut;

+ Code Snippet

x = getPointerX()
y = getPointerY()
x = x && -8
y = y && -4

Done in two steps to force to integer before the binary AND (&&).

(I don't know how AppGameKit would handle binary maths on the float returned from the pointer function)

nb.
-8 = %11111111111111111111111111111000
-4 = %11111111111111111111111111111100

So basically it ignores the lower bits and so moves in steps of 8 and 4.

Only works with numbers which are powers of 2

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Ancient Lady

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Posted: 7th Feb 2013 00:05

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Marl, since the variables you used in your snippet are all integers by default (and Tier 1 AppGameKit will recast the float values from the get pointer commands to integers), it should work. But it should be written this way, to make sure the operator precedence works the desired way:

+ Code Snippet

x = getpointerx()
y = getpointery()
x = x && (-8)
y = y && (-4)

We haven't had anyone official weigh in about the operator precedence used in the AppGameKit Tier 1 compiler. In general, most languages honor negation over bitwise operations.

Cheers,
Ancient Lady
AGK Community Tester and AppGameKit Master

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shadey

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Posted: 7th Feb 2013 10:45

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well..this is more than enough!
thanks
i was trying to divide and multiply somewhere before I asked for help but my code got all messy, had to totally recode the project but this time putting in plenty of rem blocks around the functions/vars so I don't get lost again!

Hail to the king, baby!

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shadey

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Posted: 7th Feb 2013 12:02 Edited at: 7th Feb 2013 12:50

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I know this repost is only related by the fact that it is still about the editor i am trying to write, but could you please tell me the best way to ensure that i dont place more than one sprite at the current pointer location? this is the code I have so far to give you a grasp of how it is setup:

rem Landscape App
SetDisplayAspect( 4.0/3.0 )
global cursorimage = 600
global gridx=8
global gridy=4
sprite=cre
global pointer = 600
global bricklimit=500
global brickcount = 0
global buttonload = 1
global buttonsave = 2
global buttonclear = 3
global brickimage = 1
type brick
    xloc as integer
    yloc as integer
    imagenum as integer
endtype
dim brick[500] as brick

init()

`*********************************************** Main Loop **************************************
do

print("Number of bricks: "+str(brickcount))
print("poop: "+str(v))
    x1=floor(getpointerx()/gridx)
    y1=floor(getpointery()/gridy)
    setspriteposition(pointer,x1*gridx,y1*gridy)
    lb = getvirtualbuttonstate(buttonload)
    sb = getvirtualbuttonstate(buttonsave)
    cb = getvirtualbuttonstate(buttonclear)
    state=getpointerstate()
    if v = 0
        if state>0 and brickcount<bricklimit
            inc brickcount
            createsprite(brickcount,brickimage)
            SetSpriteGroup ( brickcount,2)
            setspritesize(brickcount,8,4)
            setspriteposition (brickcount,x1*gridx,y1*gridy)
            brick[brickcount].xloc = x1*gridx
            brick[brickcount].yloc = y1*gridy
            brick[brickcount].imagenum = brickimage
        endif
    endif
    if lb>0
        clear_level()
        load_level()
    endif

if sb > 0
        save_level()
    endif
    if cb > 0
        clear_level()
    endif
    Print("hello world")
    setspritedepth(pointer,1)
    Sync()
loop
`************************************************************************************************
`
`
`
`
`
`
`************************************************* Init Function ********************************
function init()
    cursorimage = loadimage("cursor.png")
    brickimage = loadimage("redbrick.png")
    createsprite(pointer,cursorimage)
    mx# = getpointerx()
    my# = getpointery()
    setspriteposition(pointer,mx#,my#)
    setspritesize(pointer,8,4)
    AddVirtualButton(buttonload,10,10,5)
    AddVirtualButton(buttonsave,10,30,5)
    AddVirtualButton(buttonclear,80,10,5)
endfunction
`************************************************************************************************
`
`
`
`
`************************************************ Load Function *********************************
function load_level()
    myfile = OpenToread("Test2.dat")
    `brickcount = readinteger (myfile)
    for n = 1 to bricklimit
        xl = readinteger (myfile)
        yl = readinteger (myfile)
        im = readinteger (myfile)
        brick[n].xloc = xl
        brick[n].yloc = yl
        brick[n].imagenum = im
        if brick[n].imagenum <> 0
            inc brickcount
            createsprite (brickcount,brick[n].imagenum)
            SetSpriteGroup ( brickcount,2)
            setspritesize(brickcount,8,4)
            setspriteposition(brickcount,brick[n].xloc,brick[n].yloc)
        endif
    next n

closefile (myfile)
    print("loaded!!")

endfunction
`************************************************************************************************
`
`
`
`
`************************************************ Save Function *********************************
function save_level()
myfile = OpenToWrite("Test2.dat", 0)

`writeinteger (myfile,brickcount)

for n = 1 to bricklimit
    writeinteger (myfile,brick[n].xloc)
    writeinteger (myfile,brick[n].yloc)
    writeinteger (myfile,brick[n].imagenum)

next n
closefile (myfile)
print ("saved !!")

endfunction
`************************************************************************************************
`
`
`
`
`*********************************************** Clear Function *********************************
function clear_level
    deleteallsprites()
    createsprite(pointer,cursorimage)
    setspritesize(pointer,8,4)
    brickcount = 0
    sync()
endfunction
`************************************************************************************************

+ Code Snippet

rem Landscape App
SetDisplayAspect( 4.0/3.0 )
global cursorimage = 600
global gridx=8
global gridy=4
sprite=cre
global pointer = 600
global bricklimit=500
global brickcount = 0
global buttonload = 1
global buttonsave = 2
global buttonclear = 3
global brickimage = 1
type brick
    xloc as integer
    yloc as integer
    imagenum as integer
endtype
dim brick[500] as brick

init()


`*********************************************** Main Loop **************************************
do

    print("Number of bricks: "+str(brickcount))
print("poop: "+str(v))
    x1=floor(getpointerx()/gridx)
    y1=floor(getpointery()/gridy)
    setspriteposition(pointer,x1*gridx,y1*gridy)
    lb = getvirtualbuttonstate(buttonload)
    sb = getvirtualbuttonstate(buttonsave)
    cb = getvirtualbuttonstate(buttonclear)
    state=getpointerstate()
    if v = 0
        if state>0 and brickcount<bricklimit
            inc brickcount
            createsprite(brickcount,brickimage)
            SetSpriteGroup ( brickcount,2)
            setspritesize(brickcount,8,4)
            setspriteposition (brickcount,x1*gridx,y1*gridy)
            brick[brickcount].xloc = x1*gridx
            brick[brickcount].yloc = y1*gridy
            brick[brickcount].imagenum = brickimage
        endif
    endif
    if lb>0
        clear_level()
        load_level()
    endif

    if sb > 0
        save_level()
    endif
    if cb > 0
        clear_level()
    endif
    Print("hello world")
    setspritedepth(pointer,1)
    Sync()
loop
`************************************************************************************************
`
`
`
`
`
`
`************************************************* Init Function ********************************
function init()
    cursorimage = loadimage("cursor.png")
    brickimage = loadimage("redbrick.png")
    createsprite(pointer,cursorimage)
    mx# = getpointerx()
    my# = getpointery()
    setspriteposition(pointer,mx#,my#)
    setspritesize(pointer,8,4)
    AddVirtualButton(buttonload,10,10,5)
    AddVirtualButton(buttonsave,10,30,5)
    AddVirtualButton(buttonclear,80,10,5)
endfunction
`************************************************************************************************
`
`
`
`
`************************************************ Load Function *********************************
function load_level()
    myfile = OpenToread("Test2.dat")
    `brickcount = readinteger (myfile)
    for n = 1 to bricklimit
        xl = readinteger (myfile)
        yl = readinteger (myfile)
        im = readinteger (myfile)
        brick[n].xloc = xl
        brick[n].yloc = yl
        brick[n].imagenum = im
        if brick[n].imagenum <> 0
            inc brickcount
            createsprite (brickcount,brick[n].imagenum)
            SetSpriteGroup ( brickcount,2)
            setspritesize(brickcount,8,4)
            setspriteposition(brickcount,brick[n].xloc,brick[n].yloc)
        endif
    next n

    closefile (myfile)
    print("loaded!!")

endfunction
`************************************************************************************************
`
`
`
`
`************************************************ Save Function *********************************
function save_level()
myfile = OpenToWrite("Test2.dat", 0)

`writeinteger (myfile,brickcount)

for n = 1 to bricklimit
    writeinteger (myfile,brick[n].xloc)
    writeinteger (myfile,brick[n].yloc)
    writeinteger (myfile,brick[n].imagenum)

next n
closefile (myfile)
print ("saved !!")

endfunction
`************************************************************************************************
`
`
`
`
`*********************************************** Clear Function *********************************
function clear_level
    deleteallsprites()
    createsprite(pointer,cursorimage)
    setspritesize(pointer,8,4)
    brickcount = 0
    sync()
endfunction
`************************************************************************************************

I have included this zip of the project file if anyone is interested

thanks again for any help
Modified the code slightly in the zip but only added to the reset function to clear the brick type fields

rem
rem AGK Application
rem

rem Landscape App
SetDisplayAspect( 4.0/3.0 )
global cursorimage = 700
global gridx=8
global gridy=4
sprite=cre
global pointer = 700
global bricklimit=600
global brickcount = 0
global buttonload = 1
global buttonsave = 2
global buttonclear = 3
global brickimage = 1
type brick
    xloc as integer
    yloc as integer
    imagenum as integer
endtype
dim brick[600] as brick

init()

`*********************************************** Main Loop **************************************
do

print("Number of bricks: "+str(brickcount))
    print("poop: "+str(v))
    x1=floor(getpointerx()/gridx)
    y1=floor(getpointery()/gridy)
    setspriteposition(pointer,x1*gridx,y1*gridy)
    lb = getvirtualbuttonstate(buttonload)
    sb = getvirtualbuttonstate(buttonsave)
    cb = getvirtualbuttonstate(buttonclear)
    state=getpointerstate()
    `**************** Place a brick at current pointer location
    if state>0 and brickcount<bricklimit
            inc brickcount
            createsprite(brickcount,brickimage)
            SetSpriteGroup ( brickcount,2)
            setspritesize(brickcount,8,4)
            setspriteposition (brickcount,x1*gridx,y1*gridy)
            brick[brickcount].xloc = x1*gridx
            brick[brickcount].yloc = y1*gridy
            brick[brickcount].imagenum = brickimage
        endif
    endif
    if lb>0
        clear_level()
        load_level()
    endif

if sb > 0
        save_level()
    endif
    if cb > 0
        clear_level()
    endif
    Print("hello world")
    setspritedepth(pointer,1)
    Sync()
loop
`************************************************************************************************
`
`
`
`
`
`
`************************************************* Init Function ********************************
function init()
    cursorimage = loadimage("cursor.png")
    brickimage = loadimage("redbrick.png")
    createsprite(pointer,cursorimage)
    mx# = getpointerx()
    my# = getpointery()
    setspriteposition(pointer,mx#,my#)
    setspritesize(pointer,8,4)
    AddVirtualButton(buttonload,10,10,5)
    AddVirtualButton(buttonsave,10,30,5)
    AddVirtualButton(buttonclear,80,10,5)
endfunction
`************************************************************************************************
`
`
`
`
`************************************************ Load Function *********************************
function load_level()
    myfile = OpenToread("Test2.dat")
    `brickcount = readinteger (myfile)
    for n = 1 to bricklimit
        xl = readinteger (myfile)
        yl = readinteger (myfile)
        im = readinteger (myfile)
        brick[n].xloc = xl
        brick[n].yloc = yl
        brick[n].imagenum = im
        if brick[n].imagenum <> 0
            inc brickcount
            createsprite (brickcount,brick[n].imagenum)
            SetSpriteGroup ( brickcount,2)
            setspritesize(brickcount,8,4)
            setspriteposition(brickcount,brick[n].xloc,brick[n].yloc)
        endif
    next n

closefile (myfile)
    print("loaded!!")

endfunction
`************************************************************************************************
`
`
`
`
`************************************************ Save Function *********************************
function save_level()
myfile = OpenToWrite("Test2.dat", 0)

`writeinteger (myfile,brickcount)

for n = 1 to bricklimit
    writeinteger (myfile,brick[n].xloc)
    writeinteger (myfile,brick[n].yloc)
    writeinteger (myfile,brick[n].imagenum)

next n
closefile (myfile)
print ("saved !!")

endfunction
`************************************************************************************************
`
`
`
`
`*********************************************** Clear Function *********************************
function clear_level
    deleteallsprites()
    createsprite(pointer,cursorimage)
    setspritesize(pointer,8,4)
    brickcount = 0
    for n=1 to brickcount
        brick[n].xloc = 0
        brick[n].yloc = 0
        brick[n].imagenum = 0
    next n
    sync()
endfunction
`************************************************************************************************

+ Code Snippet

rem
rem AGK Application
rem

rem Landscape App
SetDisplayAspect( 4.0/3.0 )
global cursorimage = 700
global gridx=8
global gridy=4
sprite=cre
global pointer = 700
global bricklimit=600
global brickcount = 0
global buttonload = 1
global buttonsave = 2
global buttonclear = 3
global brickimage = 1
type brick
    xloc as integer
    yloc as integer
    imagenum as integer
endtype
dim brick[600] as brick

init()


`*********************************************** Main Loop **************************************
do

    print("Number of bricks: "+str(brickcount))
    print("poop: "+str(v))
    x1=floor(getpointerx()/gridx)
    y1=floor(getpointery()/gridy)
    setspriteposition(pointer,x1*gridx,y1*gridy)
    lb = getvirtualbuttonstate(buttonload)
    sb = getvirtualbuttonstate(buttonsave)
    cb = getvirtualbuttonstate(buttonclear)
    state=getpointerstate()
    `**************** Place a brick at current pointer location
    if state>0 and brickcount<bricklimit
            inc brickcount
            createsprite(brickcount,brickimage)
            SetSpriteGroup ( brickcount,2)
            setspritesize(brickcount,8,4)
            setspriteposition (brickcount,x1*gridx,y1*gridy)
            brick[brickcount].xloc = x1*gridx
            brick[brickcount].yloc = y1*gridy
            brick[brickcount].imagenum = brickimage
        endif
    endif
    if lb>0
        clear_level()
        load_level()
    endif

    if sb > 0
        save_level()
    endif
    if cb > 0
        clear_level()
    endif
    Print("hello world")
    setspritedepth(pointer,1)
    Sync()
loop
`************************************************************************************************
`
`
`
`
`
`
`************************************************* Init Function ********************************
function init()
    cursorimage = loadimage("cursor.png")
    brickimage = loadimage("redbrick.png")
    createsprite(pointer,cursorimage)
    mx# = getpointerx()
    my# = getpointery()
    setspriteposition(pointer,mx#,my#)
    setspritesize(pointer,8,4)
    AddVirtualButton(buttonload,10,10,5)
    AddVirtualButton(buttonsave,10,30,5)
    AddVirtualButton(buttonclear,80,10,5)
endfunction
`************************************************************************************************
`
`
`
`
`************************************************ Load Function *********************************
function load_level()
    myfile = OpenToread("Test2.dat")
    `brickcount = readinteger (myfile)
    for n = 1 to bricklimit
        xl = readinteger (myfile)
        yl = readinteger (myfile)
        im = readinteger (myfile)
        brick[n].xloc = xl
        brick[n].yloc = yl
        brick[n].imagenum = im
        if brick[n].imagenum <> 0
            inc brickcount
            createsprite (brickcount,brick[n].imagenum)
            SetSpriteGroup ( brickcount,2)
            setspritesize(brickcount,8,4)
            setspriteposition(brickcount,brick[n].xloc,brick[n].yloc)
        endif
    next n

    closefile (myfile)
    print("loaded!!")

endfunction
`************************************************************************************************
`
`
`
`
`************************************************ Save Function *********************************
function save_level()
myfile = OpenToWrite("Test2.dat", 0)

`writeinteger (myfile,brickcount)

for n = 1 to bricklimit
    writeinteger (myfile,brick[n].xloc)
    writeinteger (myfile,brick[n].yloc)
    writeinteger (myfile,brick[n].imagenum)

next n
closefile (myfile)
print ("saved !!")

endfunction
`************************************************************************************************
`
`
`
`
`*********************************************** Clear Function *********************************
function clear_level
    deleteallsprites()
    createsprite(pointer,cursorimage)
    setspritesize(pointer,8,4)
    brickcount = 0
    for n=1 to brickcount
        brick[n].xloc = 0
        brick[n].yloc = 0
        brick[n].imagenum = 0
    next n
    sync()
endfunction
`************************************************************************************************

Hail to the king, baby!

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Markus

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Posted: 7th Feb 2013 12:54

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before you create the sprite look at your array if there is a imagenumber.

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shadey

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Posted: 7th Feb 2013 12:56

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i was thinking that,but i dont have any real track of where it is in the array?

Hail to the king, baby!

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Markus

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Posted: 7th Feb 2013 13:13 Edited at: 7th Feb 2013 13:15

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here at "Place a brick at current pointer location"

for next and compare

for n = 1 to bricklimit
if brick[n].xloc = x1*gridx and brick[n].yloc = y1*gridy and brick[n].imagenum=0
//Add Sprite
exit
endif
next

(if you use a array[x,y] as BrickType you don't need to search.)

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shadey

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Posted: 7th Feb 2013 13:21

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tried adding the code

+ Code Snippet


    `**************** Place a brick at current pointer location
    if state>0 and brickcount<bricklimit

        for n = 1 to bricklimit
            if brick[n].xloc = x1*gridx and brick[n].yloc = y1*gridy and brick[n].imagenum=0
                inc brickcount
                createsprite(brickcount,brickimage)
                SetSpriteGroup ( brickcount,2)
                setspritesize(brickcount,8,4)
                setspriteposition (brickcount,x1*gridx,y1*gridy)
                brick[brickcount].xloc = x1*gridx
                brick[brickcount].yloc = y1*gridy
                brick[brickcount].imagenum = brickimage
                exit
            endif
        next n

    endif

it doesnt seem to want to put any sprite down..heh

I was trying to avoid for next loops and was looking into collisions via grouping instead but it never worked out for some reason

Hail to the king, baby!

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Markus

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Posted: 7th Feb 2013 13:45

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hmmm,
try with a print("yes") after if and make a else print("no") for debug

print this at screen
x1*gridx
y1*gridy
brick[n].xloc
brick[n].yloc
brick[n].imagenum

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shadey

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Posted: 7th Feb 2013 13:51 Edited at: 7th Feb 2013 13:55

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brrrr!

would help if it had a debug console on runtime!

i have tested x1*gridx and y1*gridy, they simply start at 0,0 top left and changes as they should,in increments of 8 and 4 respectively

not sure about printing the others in a for next loop though!

just added this

+ Code Snippet


    if state>0 and brickcount<bricklimit

        for n = 1 to bricklimit
            if brick[n].xloc = x1*gridx and brick[n].yloc = y1*gridy and brick[n].imagenum=0
                inc brickcount
                createsprite(brickcount,brickimage)
                SetSpriteGroup ( brickcount,2)
                setspritesize(brickcount,8,4)
                setspriteposition (brickcount,x1*gridx,y1*gridy)
                brick[brickcount].xloc = x1*gridx
                brick[brickcount].yloc = y1*gridy
                brick[brickcount].imagenum = brickimage
                print ("yes!!")
                exit
                else
                print ("NO!!")
            endif
        next n

    endif

if i have it right? anyhow it prints NO!! when i try to put one down

Hail to the king, baby!

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shadey

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Posted: 7th Feb 2013 14:01 Edited at: 7th Feb 2013 14:39

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ok i have done the rest

+ Code Snippet

`**************** Place a brick at current pointer location
    if state>0 and brickcount<bricklimit

        for n = 1 to bricklimit
            if brick[n].xloc = x1*gridx and brick[n].yloc = y1*gridy and brick[n].imagenum=0
                inc brickcount
                brick[brickcount].xloc = x1*gridx
                brick[brickcount].yloc = y1*gridy
                brick[brickcount].imagenum = brickimage
                createsprite(brickcount,brickimage)
                SetSpriteGroup ( brickcount,2)
                setspritesize(brickcount,8,4)
                setspriteposition (brickcount,x1*gridx,y1*gridy)

                print ("yes!!")
                exit
                else
                print ("NO!!")


                print (""+str(brick[brickcount].xloc))
                print (""+str(brick[brickcount].yloc))
                print (""+str(brick[brickcount].imagenum))
            endif
        next n

    endif

the last 3 values print zero..which is kinda wrong for the xloc and yloc as i was in the middle of the screen when i pressed... I have attached the full project as it stands

if you rem out the checks like so:

+ Code Snippet


 `**************** Place a brick at current pointer location
    if state>0 and brickcount<bricklimit

        `for n = 1 to bricklimit
         `   if brick[n].xloc = x1*gridx and brick[n].yloc = y1*gridy and brick[n].imagenum=0
                inc brickcount
                brick[brickcount].xloc = x1*gridx
                brick[brickcount].yloc = y1*gridy
                brick[brickcount].imagenum = brickimage
                createsprite(brickcount,brickimage)
                SetSpriteGroup ( brickcount,2)
                setspritesize(brickcount,8,4)
                setspriteposition (brickcount,x1*gridx,y1*gridy)

                print ("yes!!")
           `     exit
            `    else
             `   print ("NO!!")


                print (""+str(brick[brickcount].xloc))
                print (""+str(brick[brickcount].yloc))
                print (""+str(brick[brickcount].imagenum))
            `endif
        `next n

    endif

it will paste at will..all be it over other sprite, and saves/loads correctly( btw the top left button is to load, the one underneath that is to save, and the top right button clears the level, just thought i would say as i have yet to make the gfx for the buttons!)

Hail to the king, baby!

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shadey

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Posted: 7th Feb 2013 14:57 Edited at: 7th Feb 2013 14:59

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i suspect it is the fact that it is in a for next loop, the check could be simply missed depending on where then next 'n' is at the time of the check

Hail to the king, baby!

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DVader

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Posted: 7th Feb 2013 16:23 Edited at: 7th Feb 2013 16:24

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You could simply do a check for sprite collision at your pointer co-ordinates using getspritehit(x,y). If there is a sprite underneath the cursor do not place the tile. The spritehit command also gives you the relevant sprite number, so you could specify a range and also use it to delete sprites.

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Markus

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Posted: 7th Feb 2013 17:26 Edited at: 7th Feb 2013 17:49

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theory and practice

+ Code Snippet


    if state>0 and brickcount<bricklimit

        found=0
        for n = 1 to bricklimit
            if brick[n].xloc = x1*gridx and brick[n].yloc = y1*gridy
                found=1
                exit
            endif
        next n

        if found=0
                    //add
                    inc brickcount
                    brick[brickcount].xloc = x1*gridx
                    brick[brickcount].yloc = y1*gridy
                    brick[brickcount].imagenum = brickimage
                    spr=createsprite(brickimage)
                    SetSpriteGroup (spr,2)
                    setspritesize(spr,8,4)
                    setspriteposition (spr,brick[brickcount].xloc,brick[brickcount].yloc)
        endif

    endif

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shadey

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Posted: 7th Feb 2013 17:58

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ah,splendid, thanks markus,i was messing about with some flag before, then i messed around with the collision stuff before looking here again, but that will do.
thanks

Hail to the king, baby!

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Marl

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Posted: 7th Feb 2013 18:51 Edited at: 7th Feb 2013 18:52

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A bit of optimisation

+ Code Snippet

found=0
        for n = 1 to bricklimit
            if brick[n].xloc = x1*gridx and brick[n].yloc = y1*gridy
                found=1
                exit
            endif
        next n

        if found=0
...

pre-calculating the terms used for comparison means the multiply is only done once rather than once per loop.

+ Code Snippet

        xmatch = x1*gridx
        ymatch = y1*gridy

And since the loop variable n is incremented and compared at the next n instruction, n will always be higher than bricklimit on exiting the loop if no match is found, so You don't need the flag;

+ Code Snippet

        for n = 1 to bricklimit
            if brick[n].xloc = xmatch and brick[n].yloc = ymatch
                exit
            endif
        next n

        if n > bricklimit
...

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AppGameKit Classic Chat / pointer on a grid

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