CATMULL_SHIFT equ 16
flat_triangle_z:
; procedure drawing triangle with Z cordinate interpolation ------
; (Catmull alghoritm)--------------------------------------------
; ----------------in - eax - x1 shl 16 + y1 ----------------------
; -------------------- ebx - x2 shl 16 + y2 ----------------------
; -------------------- ecx - x3 shl 16 + y3 ----------------------
; -------------------- edx - color 0x00RRGGBB --------------------
; -------------------- esi - pointer to Z-buffer -----------------
; -------------------- edi - pointer to screen buffer-------------
; -------------------- stack : z coordinates
; -------------------- Z-buffer : each z variable as dword
; -------------------- (Z coor. as word) shl CATMULL_SHIFT
.z1 equ word[ebp+4]
.z2 equ word[ebp+6] ; each z coordinate as word integer
.z3 equ word[ebp+8]
.col equ dword[ebp-4]
.x1 equ word[ebp-6]
.y1 equ word[ebp-8]
.x2 equ word[ebp-10]
.y2 equ word[ebp-12]
.x3 equ word[ebp-14]
.y3 equ word[ebp-16]
.dx12 equ dword[ebp-20]
.dz12 equ dword[ebp-24]
.dx13 equ dword[ebp-28]
.dz13 equ dword[ebp-32]
.dx23 equ dword[ebp-36]
.dz23 equ dword[ebp-40]
.zz1 equ dword[ebp-44]
.zz2 equ dword[ebp-48]
mov ebp,esp
push edx ; store edx in variable .col
.sort2:
cmp ax,bx
jle .sort1
xchg eax,ebx
mov dx,.z1
xchg dx,.z2
mov .z1,dx
.sort1:
cmp bx,cx
jle .sort3
xchg ebx,ecx
mov dx,.z2
xchg dx,.z3
mov .z2,dx
jmp .sort2
.sort3:
push eax ; store triangle coordinates in user friendly variables
push ebx
push ecx
mov edx,80008000h ; eax,ebx,ecx are ANDd together into edx which means that
and edx,ebx ; if *all* of them are negative a sign flag is raised
and edx,ecx
and edx,eax
test edx,80008000h ; Check both X&Y at once
jne .ft_loop2_end
; cmp ax,SIZE_Y
; jle @f
; cmp bx,SIZE_Y
; jle @f
; cmp cx,SIZE_Y
; jge @f
; ror eax,16
; ror ebx,16
; ror ecx,16
; cmp ax,SIZE_X
; jle @f
; cmp bx,SIZE_X
; jle @f
; cmp cx,SIZE_X
; jle @f
; jmp .ft_loop2_end
;@@:
; sub esp,52-12
mov bx,.y2 ; calc delta 12
sub bx,.y1
jnz .ft_dx12_make
push dword 0
push dword 0
jmp .ft_dx12_done
.ft_dx12_make:
mov ax,.x2
sub ax,.x1
cwde
movsx ebx,bx
shl eax,ROUND
cdq
idiv ebx
push eax
mov ax,.z2
sub ax,.z1
cwde
shl eax,CATMULL_SHIFT
cdq
idiv ebx
push eax
.ft_dx12_done:
mov bx,.y3 ; calc delta 13
sub bx,.y1
jnz .ft_dx13_make
push dword 0
push dword 0
jmp .ft_dx13_done
.ft_dx13_make:
mov ax,.x3
sub ax,.x1
cwde
movsx ebx,bx
shl eax,ROUND
cdq
idiv ebx
push eax
mov ax,.z3
sub ax,.z1
cwde
shl eax,CATMULL_SHIFT
cdq
idiv ebx
push eax
.ft_dx13_done:
; sub esp,48
mov bx,.y3 ; calc delta 23
sub bx,.y2
jnz .gt_dx23_make
push dword 0
push dword 0
; mov .dx23,0
; mov .dz23,0
jmp .gt_dx23_done
.gt_dx23_make:
mov ax,.x3
sub ax,.x2
cwde
movsx ebx,bx
shl eax,ROUND
cdq
idiv ebx
push eax
mov ax,.z3
sub ax,.z2
cwde
shl eax,CATMULL_SHIFT
cdq
idiv ebx
push eax
; mov .dz23,eax
.gt_dx23_done:
movsx edx,.z1
shl edx,CATMULL_SHIFT
push edx
push edx
movsx eax,.x1
shl eax,ROUND ; eax - x1
mov ebx,eax ; ebx - x2
mov cx,.y1
cmp cx,.y2
jge .ft_loop1_end
.ft_loop1:
pushad
push .col
push cx ; y
sar ebx,ROUND
push bx ; x2
sar eax,ROUND
push ax ; x1
push .zz2 ; z2 shl CATMULL_SHIFT
push .zz1 ; z1 shl CATMULL_SHIFT
call flat_line_z
popad
add eax,.dx13
add ebx,.dx12
mov edx,.dz13
add .zz1,edx
mov edx,.dz12
add .zz2,edx
;end if
inc cx
cmp cx,.y2
jl .ft_loop1
.ft_loop1_end:
movsx edx,.z2
shl edx,CATMULL_SHIFT
mov .zz2,edx
movsx ebx,.x2
shl ebx,ROUND
mov cx,.y2
cmp cx,.y3
jge .ft_loop2_end
.ft_loop2:
pushad
push .col
push cx
sar ebx,ROUND
push bx
sar eax,ROUND
push ax ; x1
push .zz2 ; z2 shl CATMULL_SHIFT
push .zz1 ; z1 shl CATMULL_SHIFT
call flat_line_z
popad
add eax,.dx13
add ebx,.dx23
mov edx,.dz13
add .zz1,edx
mov edx,.dz23
add .zz2,edx
inc cx
cmp cx,.y3
jl .ft_loop2
.ft_loop2_end:
mov esp,ebp
ret 6
flat_line_z:
;----------------
;-------------in edi - pointer to screen buffer ----------------------------------
;--------------- esi - pointer to z-buffer (each Z varible dword)-----------------
;----------stack - (each z coordinate shifted shl CATMULL_SHIFT)------------------
.z1 equ dword [ebp+4]
.z2 equ dword [ebp+8]
.x1 equ word [ebp+12]
.x2 equ word [ebp+14]
.y equ word [ebp+16]
.col equ dword [ebp+18]
.dz equ dword [ebp-4]
mov ebp,esp
;; sub esp,4
mov ax,.y
or ax,ax
jl .fl_quit
mov bx,[size_y_var]
dec bx
cmp ax,bx ;[size_y_var]
; cmp ax,SIZE_Y-1
jg .fl_quit
; cmp .x1,0
; jge .fl_ok1
; cmp .x2,0
; jl .fl_quit
; .fl_ok1:
; cmp .x1,SIZE_X
; jle .fl_ok2
; cmp .x2,SIZE_X
; jg .fl_quit
; .fl_ok2:
mov ax,.x1
cmp ax,.x2
je .fl_quit
jl .fl_ok
xchg ax,.x2
mov .x1,ax
mov edx,.z1
xchg edx,.z2
mov .z1,edx
.fl_ok:
mov bx,[size_x_var]
dec bx
cmp .x1,bx ;SIZE_X-1
jg .fl_quit
cmp .x2,0
jle .fl_quit
mov eax,.z2
sub eax,.z1
cdq
mov bx,.x2
sub bx,.x1
movsx ebx,bx
idiv ebx
;; mov .dz,eax ; calculated delta - shifted .dz
push eax
cmp .x1,0
jge @f
movsx ebx,.x1
neg ebx
imul ebx
add .z1,eax
mov .x1,0
@@:
movzx edx,word[size_x_var]
cmp .x2,dx ;[size_x_var] ;SIZE_X
jl @f
mov .x2,dx ;[size_x_var] ;SIZE_X
@@:
; movzx edx,[size_x_var] ;SIZE_X
movsx eax,.y
mul edx ; edi = edi + (SIZE_X * y + x1)*3
movsx edx,.x1
add eax,edx
push eax
lea eax,[eax*3]
add edi,eax ; esi = esi + (SIZE_X * y + x1)*4
pop eax
shl eax,2
add esi,eax
mov cx,.x2
sub cx,.x1
movzx ecx,cx
mov eax,.col
mov ebx,.z1 ; ebx : curr. z
mov edx,.dz
dec ecx
jecxz .draw_last
.ddraw:
cmp ebx,dword[esi]
; cmovl [edi],eax
; cmovl [esi],ebx
jge @f
mov [edi],eax
mov [esi],ebx
; stosd ; less branches
; dec edi
; mov dword[esi],ebx
; jmp .no_skip
@@:
add edi,3
; .no_skip:
add esi,4
add ebx,edx
loop .ddraw
.draw_last:
cmp ebx,dword[esi]
jge .fl_quit
stosw
shr eax,16
stosb
mov dword[esi],ebx
.fl_quit:
mov esp,ebp
ret 18