Compared to Chris's one I think it sucks.
Posted on 2002-10-12 18:13:30 by x86asm
Not a bad start. The important thing is understanding how the algorithm works. Once you do that then optimizing it is a lot easier. But, a few things to keep in mind that are always applicable.

1. Get those 16 bit instructions out of there. Keep everything in 32 bit, or 8 bit.

2. Get that function call to DrwDot() out of your inner loop.

Keep plugging away. :)

- Chris
Posted on 2002-10-12 21:25:25 by bit
I just noticed a serious flaw in my algothrim. When I have diagonal lines, it doesnt draw the whole thing as you can see the numpixels thing tells my PROC when to stop and return to caller but as you see if the line is long and diagonal it wont draw the whole line do you know how to remedy this?
Posted on 2002-10-13 12:14:47 by x86asm
Maybe its too late for this, but here it goes.

One of the reasons that an application can run faster on a window than in fullscreen is the vertical retrace. On a windowed application the default is DONT WAIT for the vertical retrace. On a fullscreen application the default is WAIT for the vertical retrace. So basically every time there is a vertical retrace your program will wait before issuing more primitives.
Posted on 2002-10-13 13:11:40 by dxantos
In small 128/512 bytes intro for DOS... ;)

proc DrawLine
imul di,dx,XSize
add di,cx ; DI = X + Y * XSize
sub si,cx
jge dlXGr
neg si ; |dX|
std ; mX = -1
dlXGr: mov bp,XSize ; mY = XSize
sub bx,dx
jge dlYGr
neg bx ; |dY|
neg bp ; mY = -XSize
dlYGr: xor dx,dx ; U=0
cmp si,bx ; |dX|<|dY|
jl dlDYGr
mov cx,si ; cx=|dX|
inc cx
dlLopX: stosb ; DI += mX
sub dx,bx ; U -= |dY|
jge dlOnlX
add di,bp ; DI += mY
add dx,si ; U += |dX|
dlOnlX: loop dlLopX
dlDYGr: mov cx,bx ; cx=|dY|
inc cx
dlLopY: mov [es:di],al
add di,bp ; DI += mY
sub dx,si ; U -= |dX|
jge dlOnlY
scasb ; DI += mX
add dx,bx ; U += |dY|
dlOnlY: loop dlLopY

For linear interpolation may be used MMX:

macro LineMMX
movq mm0,[p0] ; {y0,x0}
movq mm1,[p1] ; {y1,x1}
movq mm3,mm0
pcmpeqd mm7,mm7
psrld mm7,31
pcmpgtd mm3,mm1
por mm3,mm7 ; {sign(y1-y0),sign(x1-x0)}
psubd mm1,mm0
movq mm2,mm1
psrad mm2,31
pxor mm1,mm2
psubd mm1,mm2 ; {abs(y1-y0),abs(x1-x0)}
pxor mm7,mm7
movq mm5,mm3
punpckldq mm5,mm7 ; {addY,0}
punpckhdq mm7,mm3 ; {0,addX}
movq mm4,mm1
punpckhdq mm4,mm4
movd ecx,mm1 ; dX
movd edx,mm4 ; dY
cmp ecx,edx
jl @@YL
macro _Line dXc, dYy, addX, addY
local @@lp,@@u
push dXc
add dYy,dYy
mov eax,dYy
sub eax,dXc ; u=2*dY-dX
lea ebx,[dXc+dXc]
@@lp: movq [edi+8*dXc],mm0
add eax,dYy ; u=u+2*dY
jle @@u
sub eax,ebx ; u=u-2*dX
paddd mm0,addY ; p=p+{addY,0}
@@u: paddd mm0,addX ; p=p+{0,addX}
dec dXc
jns @@lp
pop eax
inc eax
_Line ecx,edx,mm5,mm7
@@YL: _Line edx,ecx,mm7,mm5
Posted on 2002-10-15 11:36:10 by Nexo