I am working on a wince game and want to do some fadein/out works on a vga
screen.
I use alphablt in IDirectDrawSurface, but it only support a constant 50%
alpha.
When I blt a 320x240 image on a 480x640 screen, alphablt give me about 12
fps plus filling a backbuffer black , blt another 320x240 image and blt to
primary surface.
I found a table look method while googling and doing the same thing on
device. It can only achieve 8 fps. If pixel is cliped when out of screen,
the speed increase. About 20 fps if only draw 1/10 of the image on screen.
The numbers is reading from A HTC Touch Pro. A pretty slow device.
The following function is what I am using to blend the pixel on a back
screen surface to another back screen surface.
Any ideas how can I improve this function to as fast as the alphablt one in
Directdraw??
It seems arm can do something better then x86 tricks, most operation can
done in one cycle include mul.
procedure TDirectDrawSurface.drawAlpha(x, y: integer;
SrcSurface: TDirectDrawSurface; alpha: integer
);
var
SourceTable,DestTable : LookUpLevel;
SourceTableG,DestTableG : LookUpLevelG;
DDSURFACEinfoSrc,DDSURFACEinfoDEST : TDDSURFACEDESC;
SRCbuffer,DESTbuffer,SrcColor,DestColor : ^ushort;
nPitchDest,nPitchSrc : ushort;
i,j,xEnd,yEnd,DestLinePos,SrcLinePos, DestWidth, DestHeight,
SrcWidth,SrcHeight:integer;
function PackColor(R,G,B : byte) : ushort; inline;
begin
result := r shl 11 + g shl 5 + b;
end;
function UnpackColorR(color : ushort;RBitMask : DWORD) : byte; inline;
begin
result := color and RBitMask shr 11;
end;
function UnpackColorG(color : ushort;GBitMask : DWORD) : byte; inline;
begin
result := color and GBitMask shr 5;
end;
function UnpackColorB(color : ushort;BBitMask : DWORD) : byte; inline;
begin
result := color and BBitMask;
end;
begin
DDSURFACEinfoSrc :=SrcSurface.lock;
DDSURFACEinfoDEST := lock;
SourceTable := Alphatable.LookupPointer(Alpha);
SourceTableG := Alphatable.LookupPointerG(Alpha);
DestTable := Alphatable.LookupPointer(255 - Alpha);
DestTableG := Alphatable.LookupPointerG(255 - Alpha);
SRCbuffer := DDSURFACEinfoSRC.lpSurface;
nPitchSrc := DDSURFACEinfoSrc.lPitch shr 1;
DESTbuffer := DDSURFACEinfoDEST.lpSurface;
nPitchDest := DDSURFACEinfoDest.lPitch shr 1;
DestWidth := width;
DestHeight := Height;
SrcWidth := SrcSurface.width;
SrcHeight := SrcSurface.Height;
x := max(0,x);
y := max(0,y);
xEnd := min(x+SrcWidth-1,Destwidth-1);
yEnd := min(y+ SrcHeight-1,DestHeight-1);
SrcLinePos := 0;
DestLinePos := y*nPitchDest;
for i := y to yEnd do
begin
DestColor := @DESTbuffer[DestlinePos+x];
SrcColor := @SRCbuffer[SrcLinePos];
for j := x to xEnd do
begin
DESTbuffer[DestlinePos+j] :=
PackColor(
DestTable[UnpackColorR(DestColor^,DDSURFACEinfoSrc.ddpfPixelFormat._mask.dwRBitMask)]+
SourceTable[UnpackColorR(SrcColor^,DDSURFACEinfoSrc.ddpfPixelFormat._mask.dwRBitMask)],
DestTableG[UnpackColorG(DestColor^,DDSURFACEinfoSrc.ddpfPixelFormat._mask.dwGBitMask)]+
SourceTableG[UnpackColorG(SrcColor^,DDSURFACEinfoSrc.ddpfPixelFormat._mask.dwGBitMask)],
DestTable[UnpackColorB(DestColor^,DDSURFACEinfoSrc.ddpfPixelFormat._mask.dwBBitMask)]+
SourceTable[UnpackColorB(SrcColor^,DDSURFACEinfoSrc.ddpfPixelFormat._mask.dwBBitMask)]
);
inc(DestColor);
inc(SrcColor);
end;
inc(DestlinePos, nPitchDest);
inc(SrcLinePos, nPitchSrc);
end;
SrcSurface.unlock;
unlock;
end;
_______________________________________________
fpc-pascal maillist - fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal
