189 lines
3.5 KiB
NASM
189 lines
3.5 KiB
NASM
draw_triangle:
|
|
;----------in - eax - x1 shl 16 + y1
|
|
;------------- -ebx - x2 shl 16 + y2
|
|
;---------------ecx - x3 shl 16 + y3
|
|
;---------------edx - color 0x00rrggbb
|
|
;---------------edi - pointer to screen buffer
|
|
@ch3:
|
|
cmp ax,bx
|
|
jg @ch1
|
|
@ch4: ; sort parameters
|
|
cmp bx,cx
|
|
jg @ch2
|
|
jle @chEnd
|
|
@ch1:
|
|
xchg eax,ebx
|
|
jmp @ch4
|
|
@ch2:
|
|
xchg ebx,ecx
|
|
jmp @ch3
|
|
@chEnd:
|
|
mov dword[@y1],eax ; ....and store to user friendly variables
|
|
mov dword[@y2],ebx
|
|
mov dword[@y3],ecx
|
|
mov [@col],edx
|
|
mov edx,eax ; eax,ebx,ecx are ORd together into edx which means that
|
|
or edx,ebx ; if any *one* of them is negative a sign flag is raised
|
|
or edx,ecx
|
|
test edx,80008000h ; Check both X&Y at once
|
|
jne @end_triangle
|
|
|
|
cmp [@x1],SIZE_X ; {
|
|
jg @end_triangle
|
|
cmp [@x2],SIZE_X ; This can be optimized with effort
|
|
jg @end_triangle
|
|
cmp [@x3],SIZE_X
|
|
jg @end_triangle ; }
|
|
|
|
shr eax,16
|
|
shr ebx,16
|
|
shr ecx,16
|
|
|
|
neg ax ; calculate delta 12
|
|
add ax,bx
|
|
cwde
|
|
shl eax,ROUND
|
|
cdq
|
|
mov bx,[@y2]
|
|
mov cx,[@y1]
|
|
sub bx,cx
|
|
;cmp ebx,0
|
|
jne @noZero1
|
|
mov [@dx12],0
|
|
jmp @yesZero1
|
|
@noZero1:
|
|
idiv ebx
|
|
mov [@dx12],eax
|
|
@yesZero1:
|
|
|
|
mov ax,[@x3] ; calculate delta 13
|
|
sub ax,[@x1]
|
|
cwde
|
|
shl eax,ROUND
|
|
cdq
|
|
mov bx,[@y3]
|
|
mov cx,[@y1]
|
|
sub bx,cx
|
|
;cmp ebx,0
|
|
jne @noZero2
|
|
mov [@dx13],0
|
|
jmp @yesZero2
|
|
@noZero2:
|
|
idiv ebx
|
|
mov [@dx13],eax
|
|
@yesZero2:
|
|
|
|
mov ax,[@x3] ; calculate delta 23 [dx23]
|
|
sub ax,[@x2]
|
|
cwde
|
|
shl eax,ROUND
|
|
cdq
|
|
mov bx,[@y3]
|
|
mov cx,[@y2]
|
|
sub bx,cx
|
|
;cmp ebx,0
|
|
jne @noZero3
|
|
mov [@dx23],0
|
|
jmp @yesZero3
|
|
@noZero3:
|
|
idiv ebx
|
|
mov [@dx23],eax
|
|
@yesZero3:
|
|
|
|
movzx eax,word[@x1] ; eax - xk1
|
|
shl eax,ROUND
|
|
mov ebx,eax ; ebx - xk2
|
|
movzx esi,word[@y1] ; esi - y
|
|
@next_line1:
|
|
mov ecx,eax ; ecx - x11
|
|
sar ecx,ROUND
|
|
mov edx,ebx ; edx - x12
|
|
sar edx,ROUND
|
|
cmp ecx,edx
|
|
jle @nochg
|
|
xchg ecx,edx
|
|
@nochg:
|
|
pusha
|
|
mov ebx,ecx
|
|
sub edx,ecx
|
|
mov ecx,edx
|
|
mov edx,esi
|
|
mov eax,[@col]
|
|
call @horizontal_line
|
|
popa
|
|
add eax,[@dx13]
|
|
add ebx,[@dx12]
|
|
inc esi
|
|
cmp si,[@y2]
|
|
jl @next_line1
|
|
|
|
movzx esi,word[@y2]
|
|
movzx ebx,word[@x2]
|
|
shl ebx,ROUND
|
|
@next_line2:
|
|
mov ecx,eax
|
|
sar ecx,ROUND
|
|
mov edx,ebx
|
|
sar edx,ROUND
|
|
cmp ecx,edx
|
|
jle @nochg1
|
|
xchg ecx,edx
|
|
@nochg1:
|
|
pusha
|
|
mov ebx,ecx
|
|
sub edx,ecx
|
|
mov ecx,edx
|
|
mov edx,esi
|
|
mov eax,[@col]
|
|
call @horizontal_line
|
|
popa
|
|
add eax,[@dx13]
|
|
add ebx,[@dx23]
|
|
inc esi
|
|
cmp si,[@y3]
|
|
jl @next_line2
|
|
@end_triangle:
|
|
ret
|
|
|
|
@horizontal_line:
|
|
;---------in
|
|
;---------eax - color of line, 0x00RRGGBB
|
|
;---------ebx - x1 - x position of line begin
|
|
;---------ecx - lenght of line
|
|
;---------edx - y position of line
|
|
;---------edi - pointer to buffer
|
|
jcxz @end_hor_l
|
|
; or edx,edx
|
|
; jl @end_hor_l
|
|
cmp edx,SIZE_Y
|
|
jg @end_hor_l
|
|
push eax
|
|
mov eax,SIZE_X*3
|
|
mul edx
|
|
add edi,eax ; calculate line begin adress
|
|
;add edi,ebx
|
|
;shl ebx,1
|
|
lea edi,[edi+ebx*2]
|
|
add edi,ebx
|
|
pop eax
|
|
cld
|
|
;mov dword[edi-3],0000FF00h
|
|
@ddraw: ; Drawing horizontally:
|
|
;push eax
|
|
stosd ; 4 bytes at a time
|
|
dec edi ; point to the 4th
|
|
;shr eax,16
|
|
;stosb
|
|
;pop eax
|
|
;pusha ; If you want to draw pixel-by-pixel
|
|
; mov eax,7 ; put image
|
|
; mov ebx,screen
|
|
; mov ecx,SIZE_X shl 16 + SIZE_Y
|
|
; mov edx,5 shl 16 + 20
|
|
; int 0x40
|
|
;popa
|
|
loop @ddraw
|
|
mov byte[edi],0 ; The last 4th will be reset
|
|
@end_hor_l:
|
|
ret
|