I am setting the gamma ramp to create a fading effect and blue (when it is night). I have this example piece of code: void setblack(){ LPDIRECTDRAWGAMMACONTROL dgamma; DDGAMMARAMP gdata; unsigned short rp;//vars dsurface->QueryInterface(IID_IDirectDrawGammaControl,(LPVOID*)&dgamma); for (rp=0;rp<256;rp++){ gdata.red[rp]=0; gdata.green[rp]=0; gdata.blue[rp]=0; }; if(dgamma->SetGammaRamp(DDSGR_CALIBRATE,&gdata); }; The problem is that the method SetGammaRamp returnes not DD_OK. Is this a lack of a video card feature (I have an S3 virge 4MB, and a trust voodoo dragon 2) or am I missing something? Is there a better function for the thing I am trying to do, and does this function require 3dfx? Or should I use conventional methods (pixel substraction)? BTW, I am working in 800x600 16 bit (5-5-5).

I believe the CALIBRATE tag is only supported on certain cards. I don't have my source in front of me, but off the top of my head I don't remember the CALIBRATE tag.

Joseph Fernald wrote a great article that explained how to do gamma fades here on gamedev; take a peek at his code:

http://www.gamedev.net/reference/programming/features/gamma/




Mason McCuskey
Spin Studios - home of Quaternion, 2000 GDC Indie Games Fest Finalist!
www.spin-studios.com

Edited by - mason on 1/20/00 5:43:05 PM

Not all cards support calibrate and some cards don''t support gamma control at all in DX (Monster 3D II for one).

Exactly what error code is being returned?

--Shannon Schlomer, BLAZE Technologies, Inc.

I''ve read the article and I believe that my code isn''t different than that in the article. I don''t have the compiler at hand (my computer crashed) so I don''t know the error code it''s returning. In the article there is a line that says that when it isn''t supported by hardware the system simulates it (well, actually windows does). Maybe I should use LPDIRECTDRAW7 in stead of just LPDIRECTDRAW.

The problem is also occuring when I call GetGammaRamp. It returnes an DDERR_INVALIDPARAMS error. To make things clear here is all the code...

void initgraph(void){
WNDCLASS windclass;
windclass.style=0;
windclass.lpfnWndProc=wndmsghandler;
windclass.cbClsExtra=0;
windclass.cbWndExtra=0;
windclass.hInstance=instancehandle;
windclass.hIcon=LoadIcon(instancehandle,IDI_APPLICATION);
windclass.hCursor=LoadCursor(instancehandle,IDC_ARROW);
windclass.hbrBackground=(HBRUSH__*)GetStockObject(LTGRAY_BRUSH);
windclass.lpszMenuName=NULL;
windclass.lpszClassName="game";
RegisterClass(&windclass);
windowhandle=CreateWindow("game","initializing game",WS_OVERLAPPED,CW_USEDEFAULT,0,0,0,NULL,NULL,instancehandle,NULL);
ShowWindow(windowhandle,SW_SHOWMAXIMIZED);
if (DirectDrawCreate(NULL,&ddraw,NULL)!=DD_OK) return(false);
if (ddraw->SetCooperativeLevel(windowhandle,DDSCL_EXCLUSIVE/DDSCL_FULLSCREEN)!=DD_OK) return(false);
if (ddraw->SetDisplayMode(800,600,16)!=DD_OK) return(false);
memset(&ddesc,0,sizeof(ddesc));
ddesc.dwSize=sizeof(ddesc);
ddesc.dwFlags=DDSD_CAPS/DDSD_BACKBUFFERCOUNT;
ddesc.ddsCaps.dwCaps=DDSCAPS_PRIMARYSURFACE/DDSCAPS_FLIP/DDSCAPS_COMPLEX;
ddesc.dwBackBufferCount=1;
if (ddraw->CreateSurface(&ddesc,&dsurface,NULL)!=DD_OK) return(false);
dcaps.dwCaps=DDSCAPS_BACKBUFFER;
if (dsurface->GetAttachedSurface(&dcaps,&dbackbuf)!=DD_OK) return(false);
if(dsurface->QueryInterface(IID_IDirectDrawGammaControl,(LPVOID *)&dgamma)!=DD_OK) return(false);
if(dgamma->GetGammaRamp(0,&orggdata)!=DD_OK) return(false);
return(true);
};//initialize graphics