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bitmap.asm
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bitmap.asm
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org 100h
vga equ 0xa000
gfx_erase db 0
gfx_background_colour db 1 ; colour index for all "sprites"
gfx_width dw 0 ; using dw because it makes comparisons easier, probably a better way but i'm not known for that
gfx_height dw 0
gfx_transparent db 0 ; the index used for transparency
gfx_x_pos dw 0
gfx_y_pos dw 0
yes db 0
mov al,13h ; graphics mode: 13h (256 colour vga)
mov ah,0 ; function number
int 10h
flood_fill:
; flood fill (background colour is iffy, so we're going it manually)
mov cx,0
mov dx,0
mov al,[gfx_background_colour]
mov ah,0ch
.loop:
int 10h
inc cx
cmp cx,320
jne .loop
mov cx,0
inc dx
cmp dx,200
jne .loop
main:
; REMEMBER: with brackets refers to the data inside, without brackets refers to the offset
mov ah,3dh ; open file
mov al,0 ; read
mov dx,bloke_gfx ; load OFFSET of bloke_gfx
int 21h
mov word [file_handle],ax ; for future usage
mov ah,3fh ; read from file
mov bx,[file_handle] ; load VALUE OF file_handle into bx
mov cx,902h
mov dx,gfx_buffer
int 21h
.loop:
mov byte [gfx_erase],0
call draw_gfx
add word [gfx_x_pos],50
add word [gfx_y_pos],50
call draw_gfx
sub word [gfx_x_pos],50
sub word [gfx_y_pos],50
mov ecx,62000
.delay:
nop
loop .delay
mov byte [gfx_erase],1
call draw_gfx
add word [gfx_x_pos],50
add word [gfx_y_pos],50
call draw_gfx
sub word [gfx_x_pos],50
sub word [gfx_y_pos],50
inc word [gfx_x_pos]
inc word [gfx_y_pos]
;mov ah,4ch
;int 21h
jmp .loop
draw_gfx:
; graphics are stored x first, then y
mov ax,[gfx_buffer] ; first byte should contain the width
mov byte [gfx_width],al
mov ax,[gfx_buffer+1] ; second byte should contain the height
mov byte [gfx_height],al
mov ax,[gfx_buffer+2] ; top left pixel is assumed transparent
mov byte [gfx_transparent],al
mov si,2 ; beginning of actual graphic data
mov cx,[gfx_x_pos] ; x
mov dx,[gfx_y_pos] ; y
.loop:
mov al,[gfx_buffer+si] ; pixel colour
cmp al,[gfx_transparent]
je .skip ; if the pixel is "transparent", skip drawing
cmp byte [gfx_erase],0 ; otherwise, check if we're erasing so we use the right colour
je .erase_skip ; if not, use the proper colour as set earlier
mov al,[gfx_background_colour] ; otherwise, use background colour
.erase_skip:
mov ah,0ch ; draw that bad boy
int 10h
.skip:
inc si ; next byte
inc cx ; increase x
mov ax,cx
sub ax,[gfx_x_pos] ; new x - original x
cmp ax,[gfx_width] ; reached the end of the line?
jb .loop ; if not, go to next horizontal pixel
mov cx,[gfx_x_pos] ; we've reached the end of the line, so reset x and increase y
inc dx
mov ax,dx
sub ax,[gfx_y_pos] ; new y - original y
cmp ax,[gfx_height] ; reached the bottom of the graphic?
jb .loop ; if not, go to next line
ret
file_handle: db 0
bloke_gfx: db "birz.gfx",0
yup: db "yup.yup",0
gfx_buffer: db ?
msg: db "oops something bad has bappened",13,10,"$"