Hello Readers,

I am attempting to use XAllocColorCells to allocate a color map for
for a colour-index opengl window on my workstation.

Firstly I trying to determine the number of colours that I can create?

From my program I find that only 242 can be allocated with XAllocColorCells.

This is a bit strange since xdpyinfo gives the following information.

depth of root window: 8 planes
number of colormaps: minimum 1, maximum 1
default colormap: 0x21
default number of colormap cells: 256
preallocated pixels: black 0, white 1

default visual id: 0x22
visual:
visual id: 0x22
class: PseudoColor
depth: 8 planes
size of colormap: 256 entries
red, green, blue masks: 0x0, 0x0, 0x0
significant bits in color specification: 8 bits

What is the number of colors that I can define???

Why does XAllocColorCells fail above 242??

Unfortuately when I try to define the colors I get a black screen.

Here is the code I am using?

int maxcolor;
maxcolor = 242;
unsigned long pixels[256];
GLint IndexMap[256];
XColor xcolours[256];
long status;

status = XAllocColorCells(display, cmap, False, NULL, 0, pixels, maxcolor );

if (status == 0) printf("Failed to allocate color cells\n");

for (n = 0; n < maxcolor; n++)
{
IndexMap[n] = pixels[n];
xcolours[n].pixel = pixels[n];
xcolours[n].red = (long)(n << 8);
xcolours[n].blue = (long)(n << 8);
xcolours[n].green = (long)(n << 8);
xcolours[n].flags = DoRed | DoGreen | DoBlue;
}

XStoreColors(display, cmap, xcolours, maxcolor);

Could it be explained what I have done wrong when creating my colourmap?

Thanks

Stuart