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Back to Graphics and GPU Programming

Direct Draw - Setting Pixel Value

Graphics and GPU Programming Programming

Started by B4 November 30, 1999 10:07 AM

4 comments, last by B4 24 years, 7 months ago

acw83

174

November 27, 1999 03:56 PM

Try this(I am assuming 8 bit color):

BYTE mycolor;
BYTE *sptr;

sptr = g_pDDSOne->Lock(NULL,&ddsd,DDLOCK_WAIT,NULL);
sptr[x + (y*ddsd.lpitch)] = mycolor;
g_pDDOne->Unlock();

Atavist

122

November 27, 1999 06:04 PM

One thing I didn't see you do that is very important is initialize your ddsd!

ddsd.dwSize = sizeof(ddsd); (i think)

Otherwise direct draw doesnt know what to make of it.

Just because the church was wrong doesn't mean Galileo wasn't a heretic.It just means he was a heretic who was right.

Starfall

122

November 27, 1999 07:19 PM

You should be clearing your DDSURFACEDESC also:

memset(&ddsd, 0, sizeof(DDSURFACEDESC));

Good luck!

Starfall

NightShade

122

November 29, 1999 02:37 PM

On that note you should check the return value of the lock to make sure it worked.
(Just pointing out the obvious, which I'm sure you probably already did hehehe (but then again, maybe not))
-ns

-ns-

122

Author

November 30, 1999 10:07 AM

I am trying to set a pixel to a certain color using Direct Draw, but my method seems to make the computer crash. I first find the value of the pixel by doing the following:
DDSURFACEDESC2 ddsd;
int mycolor;
BYTE *sptr;
HRESULT hRet;

hRet = g_pDDSOne->Lock(NULL, &ddsd, DDLOCK_WAIT, NULL);
sptr = (BYTE*) ddsd.lpSurface;
sptr++;
mycolor = *sptr; g_pDDSOne->Unlock(NULL);

I was having some problems with this code as well, when I tried printing the value of mycolor to a file, it crashed again. I tried
setting the pixel value by saying
*sptr = 255; but this did not work (I did this before Unlocking). Could someone help me out please?