🚀 go-pugleaf

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Benjamin M. Burack schrieb in Nachricht ...
>My program loads 24-bit textures and displays them with Mesa on XWindows
>with a Voodoo2 card.  I'm using double-buffering and depth buffering in
RGBA
>mode (not color index).  For some reason, I am losing a lot of my colors.
>For example, if I have a texture with 8 similar shades of gray, many will
>appear as exactly the same color.  Only 2 or 3 shades will be rendered for
>all 8.  Since my program involves subtle contrast variations, this is a
huge
>problem.  I thought I would be running in a true color mode since X is set
>to 24 or 32 bit color depth, but apparently this isn't the case.  Why does
>this happen?  How can I fix it?
>
>Posted below is some of the code, such as the colormap initialization, that
>may cause the problem.
>
>Thanks for any help, and please mail responses to rascal@tseinc.com ,
>Benjamin Burack
>
>
>
>
>
>int configuration[] = {GLX_DOUBLEBUFFER, GLX_RGBA, GLX_DEPTH_SIZE, 16,
>None};
>
>void main(int argc, char **argv)
>{
>    XVisualInfo    *vi;
>    XSetWindowAttributes swa;
>    XWMHints       *wmHints;
>    Atom            wmDeleteWindow;
>    GLXContext      cx;
>
><snip>
>
>
>    /*** find an appropriate visual and a colormap for it ***/
>    /* find an OpenGL-capable RGB visual with depth buffer */
>    if (!bDoubleBuffer) goto SingleBufferOverride;
>    vi = glXChooseVisual(pDisplay, DefaultScreen(pDisplay), configuration);
>    if (vi == NULL) {
>      SingleBufferOverride:
>        vi = glXChooseVisual(pDisplay, DefaultScreen(pDisplay),
>&configuration[1]);
>        if (vi == NULL)
>            fatal_error("no appropriate RGB visual with depth buffer");
>        bDoubleBuffer = GL_FALSE;
>    }
>    cmap = getColormap(vi);
>
><snip>
>
>    /*** create an OpenGL rendering context  ***/
>    cx = glXCreateContext(pDisplay, vi, /* no sharing of display lists */
>NULL,
>                           /* direct rendering if possible */ GL_TRUE);
>    if (cx == NULL) fatal_error("could not create rendering context");
>
><snip>
>
>}
>
>Colormap getColormap(XVisualInfo* vi)
>{
>  Status           status;
>  XStandardColormap* standardCmaps;
>  Colormap         cmap;
>  int              i, numCmaps;
>
>  status = XmuLookupStandardColormap(pDisplay, vi->screen, vi->visualid,
>vi->depth, XA_RGB_DEFAULT_MAP, FALSE, TRUE);
>
>  if (status == 1) {
>    status = XGetRGBColormaps(pDisplay, RootWindow(pDisplay, vi->screen),
>         &standardCmaps, &numCmaps, XA_RGB_DEFAULT_MAP);
>    if (status == 1)
>      for (i = 0; i < numCmaps; i++)
> if (standardCmaps[i].visualid == vi->visualid) {
>   cmap = standardCmaps[i].colormap;
>   XFree(standardCmaps);
>   return cmap;
> }
>  }
>  cmap = XCreateColormap(pDisplay, RootWindow(pDisplay, vi->screen),
>    vi->visual, AllocNone);
>  return cmap;
>}
>
>
>