Game Development

DirectDraw 8-bit color algorithm

Please support our Game Development advertiser: Programming Forums - DaniWeb Sister Site

Thread Solved

•

Join Date: Apr 2006

Posts: 357

Reputation: death_oclock will become famous soon enough

Solved Threads: 37

death_oclock death_oclock is offline

Offline

Posting Whiz

DirectDraw 8-bit color algorithm

Jul 29th, 2008

I am using DirectDraw to make a game and I am running it in 8-bit color mode. What I am having a problem with is making a macro to convert RGB values into a single 8-bit color.
Here is the macro:

Help with Code Tags

c++ Syntax (Toggle Plain Text)

#define RGB_8BIT(r, g, b) ((r & 224) + ((g & 224) >> 3) + (b >> 6))

Here's my setPixel function:

 Help with Code Tags 
 c++ Syntax (Toggle Plain Text) 
VOID setPixel(INT x, INT y, BYTE color)
{
	lpScreen[x + y * lPitch] = color;
}
VOID setPixel(INT x, INT y, BYTE color)
{
	lpScreen[x + y * lPitch] = color;
}

lpScreen is defined as an array of BYTEs.
And here is the implementation in WinMain:

 Help with Code Tags 
 c++ Syntax (Toggle Plain Text) 
setPixel(0, 0, RGB_8BIT(255, 0, 0));
setPixel(0, 0, RGB_8BIT(255, 0, 0));

For some reason, this comes out as a greenish-blue when it should be pure red.

•