Alpha blend 32

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Bondy

Joined: 27 Nov 2005
Posts: 9

Bondy 29 Nov 2005, 03:26

Created a raw image with an Alpha channel i.e. 32bpp had to do this by hand unfortunately.

using the same equation subroutine this is the result

Corrected a mistake new source & binary sorry

Description:		Download
Filename:	32bit Alpha Blend.zip
Filesize:	40.93 KB
Downloaded:	944 Time(s)

Last edited by Bondy on 29 Nov 2005, 21:29; edited 2 times in total

29 Nov 2005, 03:26

Madis731

Joined: 25 Sep 2003
Posts: 2139
Location: Estonia

Madis731 29 Nov 2005, 14:56

Sorry, I'm an optimizing guy so I couldn't resist Very Happy

Code:

AlphaBlendMMX:

  movd      mm0,eax                  ; 0RGB
  movd      mm1,ebx                  ; 0RGB
  movd      mm2,ecx                  ; 000A
  punpcklwd mm2,mm2                  ; 00000A0A
  punpckldq mm2,mm2                  ; 0A0A0A0A
  pxor      mm3,mm3                  ; 00000000

  movq      mm4,mm0                  ; 00000RGB
  movq      mm5,mm1                  ; 00000RGB

  punpcklbw mm4,mm3                  ; 000R0G0B
  punpcklbw mm5,mm3                  ; 000R0G0B
  psubw     mm4,mm5                  ; Fore-Back

  pmullw    mm4,mm2                  ; (Fore-Back)*A
  psrlw     mm4,8                    ; (Fore-Back)*A/256
  paddw     mm4,mm5                  ; (Fore-Back)*A/256+Back
                                     ; 000R0G0B
  packuswb  mm4,mm4                  ; 0RGB0RGB
  movd      eax,mm4

  ret

29 Nov 2005, 14:56

Bondy

Joined: 27 Nov 2005
Posts: 9

Bondy 29 Nov 2005, 21:36

Madis731

tried your code couldnt get it to work with any colour but blue dont know why but I did find a problem with my stuff while I was checking so Ive posted new code above.

hope you can see what the problem is

29 Nov 2005, 21:36

Bondy

Joined: 27 Nov 2005
Posts: 9

Bondy 30 Nov 2005, 02:49

Madis731 sorry Dude fixed it myself and saved two movq's

Code:


AlphaBlendMMX:

  movd        mm0,eax                  ; 0RGB
  movd        mm1,ebx                  ; 0RGB
  movd        mm2,ecx                  ; 000A

  punpcklwd   mm2,mm2                  ; 00000A0A
  punpcklwd   mm2,mm2                  ; 0A0A0A0A
  pxor        mm3,mm3                  ; 00000000

  punpcklbw   mm0,mm3                  ; 000R0G0B
  punpcklbw   mm1,mm3                  ; 000R0G0B

  psubw       mm0,mm1                  ; Fore-Back
  pmullw      mm0,mm2                  ; (Fore-Back)*A
  psraw       mm0,8                    ; (Fore-Back)*A/256
  paddw       mm0,mm1                  ; (Fore-Back)*A/256+Back
                                       ; 000R0G0B
  packuswb    mm0,mm0                  ; 0RGB0RGB
  movd        eax,mm0                  ; 0RGB

  ret

See Attached I call it Alpha on the move Very Happy

30 Nov 2005, 02:49

Madis731

Joined: 25 Sep 2003
Posts: 2139
Location: Estonia

Madis731 30 Nov 2005, 07:45

I'm glad to hear you got it working. I can't get the first one working under 64-bit version, but later I will test it on a 32-bit one. The second attachment is dead (I don't know why) Sad

30 Nov 2005, 07:45

Bondy

Joined: 27 Nov 2005
Posts: 9

Bondy 01 Dec 2005, 06:57

Here it is again

Description:		Download
Filename:	Alpha Blend 2mmx.zip
Filesize:	25.51 KB
Downloaded:	941 Time(s)

01 Dec 2005, 06:57

Madis731

Joined: 25 Sep 2003
Posts: 2139
Location: Estonia

Madis731 01 Dec 2005, 09:48

Nice implementation!
I love that it is about two times shorter (the blending code), but did it give any speed advantages? I'm sorry, but I still haven't reached testing it. Weekend is coming, though Very Happy

EDIT: Ok, hmm, seems rather optimal to me. 18MHz on a 3Gig machine, I saw from the code that the delay is 50ms so (20FPS) 1 pass takes about 900kHz (just under million clocks). I expect even lower values from Pentium III - I'll let you know.

01 Dec 2005, 09:48

Bondy

Joined: 27 Nov 2005
Posts: 9

Bondy 01 Dec 2005, 15:06

Sorry found another problem with MMX code because the maths is done in 16bpp it causes errors if you increase the alpha value above a certain point.

try an alpha value of 255 to see what I mean.

original code works but I agree it would be nice to have an optimized version.

01 Dec 2005, 15:06

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