kolibrios-fun/programs/demos/view3ds/grd_line.inc

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; Line drawing procedure by Pablo Reda.
; Gouraud extension by Maciej Guba.
;****************************************************
line_grd: ; eax=x1 ebx=y1 ecx=x2 edx=y2
; xmm0 - color1 argb as 4 dword float
; xmm1 - color2 argb as 4 dword float
; xmm2 - z1 as dword float
; xmm3 - z2 as dword float
; mm0 - Z buffer
; mm1 - screen buffer
; mm2 - screen width
cmp ebx,edx
; je horizontal_grd
jg .noswap
xchg eax,ecx
xchg ebx,edx
movaps xmm7,xmm0
movaps xmm0,xmm1
movaps xmm1,xmm7
movaps xmm7,xmm2
movaps xmm2,xmm3
movaps xmm3,xmm7
.noswap:
cvtsi2ss xmm7,eax
cvtsi2ss xmm6,ebx
cvtsi2ss xmm5,ecx
cvtsi2ss xmm4,edx
subss xmm7,xmm5
subss xmm6,xmm4
andps xmm7,[abs_mask] ; 0x7fff
andps xmm6,[abs_mask] ; 0x7fff
maxss xmm7,xmm6 ; xmm7 - delta
shufps xmm7,xmm7,0
movaps xmm6,xmm3
rcpps xmm7,xmm7
subss xmm6,xmm2
mulss xmm6,xmm7 ; xmm6 - delta z
movaps xmm5,xmm1
subps xmm5,xmm0
mulps xmm5,xmm7 ; xmm5 - delta col argb
shl eax,16
shl ecx,16
sub eax,ecx
push ebx
push edx
sub ebx,edx
add ebx,1
cdq
idiv ebx
mov esi,eax
add ecx,$7fff
pop ebx
pop edx
.lineas:
mov eax,ecx
add eax,esi
push ebx
push eax
push edx
shr ecx,16
shr eax,16
call horizontal_grd
pop edx
pop ecx
pop ebx
add ebx,1
cmp ebx,edx
jle .lineas
ret
horizontal_grd: ; eax=x1 ebx=y1 ecx=x2
cmp ecx,eax
jg .m
xchg ecx,eax
.m:
sub ecx,eax
jnz .nn
add ecx,1
.nn:
movd edx,mm2
imul ebx,edx
add eax,ebx
movd edi,mm1
lea edi,[edi+eax*4]
push eax
push ebx
movd ebx,mm0
lea ebx,[ebx+eax*4]
.l:
; movss xmm4,xmm2 ; xmm2 - cur z
; cmpnltss xmm4,[ebx]
; movd eax,xmm4
; or eax,eax
; jnz @f
comiss xmm2,[ebx]
jng @f
movaps xmm4,xmm0 ; xmm0 - cur col
cvtps2dq xmm4,xmm4
packssdw xmm4,xmm4
packuswb xmm4,xmm4
movd [edi],xmm4
@@:
addss xmm2,xmm6
addps xmm0,xmm5
add edi,4
sub ecx,1
jnz .l
pop ebx
pop eax
ret