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draw_triangle.asm
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draw_triangle.asm
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extern _draw_triangle_c_ref_flp_32bpp
draw_triangle_ref_flp_32bpp:
; edi: surface
; ebx: pitch
; WIDTH, HEIGHT
; face, ebp: _face struct with
; .v0, .v1, .v2 - indexes into vertexes_t array of (dword x, dword y) coords
; .col
; uses MMX, use femms or emms
[section .bss]
p0:
x0 resd 1
y0 resd 1
p1:
x1 resd 1
y1 resd 1
p2:
x2 resd 1
y2 resd 1
ix resd 1
ix2 resd 1
__SECT__
mov eax, vertexes_t
movq mm0, [eax]
movq mm1, [eax+8]
movq mm2, [eax+16]
movq [p0], mm0
movq [p1], mm1
movq [p2], mm2
; sort points according to height
int3
; if (p1.y < p0.y) swap (p0,p1)
mov eax, [y1]
cmp eax, [y0]
jge .sorted1
; swap p0/p1
movq mm0, [p0]
movq mm1, [p1]
movq [p0], mm1
movq [p1], mm0
.sorted1:
; if (p2.y < p0.y) swap (p0,p2)
mov ecx, [y2] ; NOTE: ecx == y0, used later
cmp ecx, [y0]
jge .sorted2
; swap p0/p2
movq mm0, [p0]
movq mm1, [p2]
movq [p0], mm1
movq [p2], mm0
.sorted2:
; if (p2.y < p1.y) swap (p1,p2)
mov eax, [y2]
cmp eax, [y1]
jge .sorted3
; swap p1/p2
movq mm0, [p1]
movq mm1, [p2]
movq [p1], mm1
movq [p2], mm0
.sorted3:
emms
%if 1
; calc dx/dy to p1
int3
fild dword [x0] ; x0
fild dword [x1] ; x1 | x0
fsub st0, st1 ; x1-x0 ; dx1 | x0
fild dword [y0] ; y0 | dx1 | x0
fild dword [y1] ; y1 | y0 | dx1 | x0
fsub st0, st1 ; y1-y0 ; dy1 | y0 | dx1 | x0
ftst
fnstsw ax
sahf
jnz .dy1nz
; dy1 == 0.0 | y0 | dx1 | x0
fstp st2
; y0 | dxdy1 == 0.0 | x0
jmp .l0
.dy1nz:
fdivp st2, st0 ; dx1/dy1 ; y0 | dxdy1 | x0
.l0:
; y0 | dxdy1 | x0
; calc dx/dy to p2
fild dword [x2] ; x2 | y0 | dxdy1 | x0
fsub st0, st3 ; x2-x0 ; dx2 | y0 | dxdy1 | x0
fild dword [y2] ; y2 | dx2 | y0 | dxdy1 | x0
fsub st0, st2 ; y2-y0 ; dy2 | dx2 | y0 | dxdy1 | x0
ftst
fnstsw ax
sahf
jnz .dy2nz
; dy2 == 0.0 | dx2 | y0 | dxdy1 | x0
fstp st1
; dxdy2 == 0.0 | y0 | dxdy1 | x0
jmp .l1
.dy2nz:
fdivp st1, st0 ; dx2/dy2 ; dxdy2 | y0 | dxdy1 | x0
.l1:
; the edge with the smallest dxdy is the left edge
fcomi st0, st2
jb .dxdy2smallest
; dxdy1 is smallest
fxch st2
.dxdy2smallest:
; dxdyL: dxdy for left edge
; dxdyR: dxdy for right edhe
; dxdyL | y0 | dxdyR | x0
fstp st1 ; dxdyL | dxdyR | x0
; let y go from y0 to y1 to trace upper half
; NOTE: ecx == y0
; ebx == pitch
; edi == surface
fxch st2
; x0 | dxdyR | dxdyL
fst st3
; x0 | dxdyR | dxdyL | x0
.traceupper:
; xL | dxdyR | dxdyL | xR
fist dword [ix]
fxch st3
fist dword [ix2]
fxch st3
mov eax, ecx ; ecx = y0
mul ebx
mov edx, [ix]
lea eax, [eax+edx*4]
mov esi, [ix2]
sub esi, edx
jz .skip_scanlineupper
.scanlineupper:
mov dword [edi+eax], 0x0
add eax, 4
dec esi
jnz .scanlineupper
.skip_scanlineupper:
; calc new x
; xL | dxdyR | dxdyL | xR
fadd st0, st2
fxch st3
fadd st0, st1
fxch st3
inc ecx
cmp ecx, [y1]
jna .traceupper
; xL | dxdyR | dxdyL | xR
fild dword [x1]
fstp st4
fild dword [x2] ; x2 | xL | dxdyR | dxdyL | x1
fsubr st0, st4
fild dword [y2]
fisub dword [y1]
fdivp st1, st0
fstp st2
; xL | dxdyR2 | dxdyL | x1
.tracelower:
; xL | dxdyR2 | dxdyL | xR
fist dword [ix]
fxch st3
fist dword [ix2]
fxch st3
mov eax, ecx ; ecx = y
mul ebx
mov edx, [ix]
lea eax, [eax+edx*4]
mov esi, [ix2]
sub esi, edx
jz .skip_scanlinelower
.scanlinelower:
mov dword [edi+eax], 0x0
add eax, 4
dec esi
jnz .scanlinelower
.skip_scanlinelower:
; calc new x
; xL | dxdyR2 | dxdyL | xR
fadd st0, st2
fxch st3
fsub st0, st1
fxch st3
inc ecx
cmp ecx, [y2]
jna .tracelower
%endif
%if 1
; color p0 red, p1 green, p2 blue
mov eax, [y0]
mul ebx
mov ecx, [x0]
lea eax, [eax+ecx*4]
mov ecx, 0xff0000
mov dword [edi+eax], ecx
mov eax, [y1]
mul ebx
mov ecx, [x1]
lea eax, [eax+ecx*4]
mov ecx, 0x00ff00
mov dword [edi+eax], ecx
mov eax, [y2]
mul ebx
mov ecx, [x2]
lea eax, [eax+ecx*4]
mov ecx, 0x0000ff
mov dword [edi+eax], ecx
%endif
ret