'''
''' playfield tutorial - part 4
''' putting the playfield in a file
'''
''' by greg smith
'''

'''
''' use c coordinates
'''
OPTION C_COORDS

'''
''' turn off escape processing for speed
'''
OPTION ESCAPE OFF

dim x as int  'position of lemming from 0-480
dim y as int  'position of lemming from 0-300
dim z_dir as int  'which direction of lemming
dim z_cnt as int  'animation image of lemming

dim sprite_field as int 'the sprite number of the playfield sprites
dim sprite_lemming as int   'the sprite number of the lemming sprites
dim lemming_left as int     'index into lemming sprite for going left
dim lemming_right as int    'index into lemming sprite for going right
dim lemming_up as int       'index into lemming sprite for going up
dim lemming_down as int     'index into lemming sprite for going down

dim collision_street as char     'the street's collision value

dim collision_table[30,31] as char 'the collision table

'''
''' update file - copy file from app to flash
'''
sub update_file(fname[] as char)
    inline File_remove(fname);
    inline _load(fname);
end sub

'''
''' initialization
'''
sub init
    update_file("playfield1.dat") 'get the .dat file into flash


    sprite_field = 0  'playfield sprite
    sprite_lemming = 31    'lemming sprite is largest possible sprite - on top

    lemming_left=0        'lemming left image
    lemming_right=5       'lemming right image
    lemming_up=10         'lemming up image
    lemming_down=15       'lemming down image

    '''
    ''' the lemming has 20 bitmaps 5 for each direction
    sprite sprite_lemming, "lemming.pic"

    '''
    ''' the lemming can be anywhere on the playfield from
    ''' x = 0-480
    ''' y = 0-300
    x=240  'center of the playfield
    y=150  'center of the playfield
    z_dir=lemming_right  ' lemming faces right
    z_cnt=0              ' animation counter

    '''
    ''' set the collision flags
    '''
    collision_street = \x\
end sub

sub repaint
    dim field_x as int   '0,1,2 for the horizontal bitmap
    dim field_y as int   '0,1,2 for the vertical bitmap
    dim field as int     '0-8 for the bitmap currently visible
    dim lemming_x as int     '0-159 for the x coord on the screen
    dim lemming_y as int     '0-99  for the y coord on the screen

    field_x = x / 160    ' compute the horizontal bitmap
    field_y = y / 100    ' compute the vertical bitmap
    field = field_y*3 + field_x ' combine them to compute the bitmap number

    lemming_x = x mod 160  ' compute the lemming's position on the screen
    lemming_y = y mod 100  ' compute the lemming's position on the screen

    move sprite_field, 0, 0, field  'display the current field
    move sprite_lemming, lemming_x, lemming_y, z_dir+z_cnt 'display the lemming 

    paper white  'transparent color for the lemming
    ink ltgrey

    redraw        'redraw all the sprites
    
end sub

'''
''' increment the z_cnt variable
'''
sub update_z_cnt
    z_cnt=(z_cnt+1) MOD 5
end sub

'''
''' check for collision against table
'''
function collision_check(x as int, y as int) as char
    collision_check = collision_table[y/10,x/16]
end function

'''
''' process the keyboard
'''
sub get_keys
    dim tmp as int
    if key(#KEY_UP) then   'move the lemming up
        tmp=y-3
        if collision_check(x,tmp) = collision_street then
            y=tmp
            z_dir=lemming_up
            update_z_cnt
        end if
    end if
    if key(#KEY_DOWN) then 'move the lemming down
        tmp=y+3
        if collision_check(x,tmp) = collision_street then
            y=tmp
            z_dir=lemming_down
            update_z_cnt
        end if
    end if
    if key(#KEY_LEFT) then 'move the lemming left
        tmp=x-3
        if collision_check(tmp,y) = collision_street then
            x=tmp
            z_dir=lemming_left
            update_z_cnt
        end if
    end if
    if key(#KEY_RIGHT) then 'move the lemming right
        tmp=x+3
        if collision_check(tmp,y) = collision_street then
            x=tmp
            z_dir=lemming_right
            update_z_cnt
        end if
    end if
end sub

'''
''' get a string from the file
''' a string ends in CR/LF
'''
sub getstring(f as int, s[] as char)
    dim x as char
    dim n as int

    n=0

    while(true)
        get f,,x
        if x<>13 then
            if x=10 then exit while
            s[n] = x
            s[n+1] = 0
            n=n+1
        endif
    wend
end sub

'''
''' read the playfield file defined by
''' 'field' and set up the sprites and
''' the collision table
'''
sub init_playfield(field as int)
    dim fname[32] as char
    dim s[32] as char

    cls
    print "Loading..."

    ''' create the filename to read
    sprint fname, "playfield", field, ".dat"

    ''' open the playfield definition file
    open fname for read as 1

    getstring(1, s) 'get the sprite name

    '''
    ''' the playfield sprite has 9 bitmaps
    ''' one for each of the different areas of the
    ''' playfield
    sprite sprite_field, s

    '''
    ''' read the 30 playfield collision rows
    '''
    for i=0 to 29
        getstring(1, collision_table[i])
    next

    '''
    ''' close the playfield.dat file
    '''
    close 1
end sub

'''
''' main subroutine
'''
sub mainsub
    init
    init_playfield(1)

    while true
        inline _escape(0); /* check the escape key */
        repaint
        get_keys
    wend
end sub

'''
''' call the main subroutine
'''
mainsub