glxbackend.cpp

   1 #include "glxbackend.h"
   2
   3 #include <stdio.h>
   4 #include <assert.h>
   5 #include <GL/glxext.h>
   6 #include <string>
   7
   8 /* attributes for a double buffered visual in RGBA format with at least
   9 * 4 bits per color */
  10 static int attrList[] =
  11 {
  12         GLX_RGBA, GLX_DOUBLEBUFFER,
  13         GLX_RED_SIZE, 4,
  14         GLX_GREEN_SIZE, 4,
  15         GLX_BLUE_SIZE, 4,
  16         None
  17 };
  18
  19 VisualID GLXBackend::initialize(Display *display)
  20 {
  21         if (this->display == NULL) { // this implies that the context is also unitialized
  22                 this->display = display;
  23                 // debugging: show version information
  24                 int glxMajor, glxMinor;
  25                 glXQueryVersion(display, &glxMajor, &glxMinor);
  26                 printf("Using GLX version %d.%d\n", glxMajor, glxMinor);
  27                 // check for swap control functions
  28                 const char *extensions = glXQueryExtensionsString(display, DefaultScreen(display));
  29                 if (std::string(extensions).find("GLX_MESA_swap_control") != std::string::npos) {
  30                         funSwapIntervalMesa = (PFNGLXSWAPINTERVALMESAPROC)glXGetProcAddress((const GLubyte*)"glXSwapIntervalMESA");
  31                         if (funSwapIntervalMesa) printf("glXSwapIntervalMESA is present\n");
  32                 }
  33                 else {
  34                         funSwapIntervalMesa = 0;
  35                 }
  36                 if (std::string(extensions).find("GLX_EXT_swap_control") != std::string::npos) {
  37                         funSwapIntervalExt = (PFNGLXSWAPINTERVALEXTPROC)glXGetProcAddress((const GLubyte*)"glXSwapIntervalEXT");
  38                         if (funSwapIntervalExt) printf("glXSwapIntervalEXT is present\n");
  39                 }
  40                 else {
  41                         funSwapIntervalExt = 0;
  42                 }
  43                 // get the visual
  44                 vi = glXChooseVisual(display, DefaultScreen(display), attrList);
  45         }
  46         return vi->visualid;
  47 }
  48
  49 void GLXBackend::createContext(Window window)
  50 {
  51         assert(display != NULL && context == None);
  52         this->window = window;
  53         // create context with that window
  54         context = glXCreateContext(display, vi, 0, GL_TRUE);
  55         glXMakeCurrent(display, window, context);
  56         assert(glXIsDirect(display, context));
  57 }
  58
  59 GLXBackend::~GLXBackend()
  60 {
  61         if (display != NULL) {
  62                 if (context != None) {
  63                         glXMakeCurrent(display, None, NULL);
  64                         glXDestroyContext(display, context);
  65                 }
  66                 XFree(vi);
  67         }
  68 }
  69
  70 void GLXBackend::swapBuffers() const
  71 {
  72         assert(context != None); // this implies the display is also initialized
  73         glXSwapBuffers(display, window);
  74 }
  75
  76 void GLXBackend::setSwapInterval(int i) const
  77 {
  78         assert(context != None);
  79         if (funSwapIntervalExt)
  80                 funSwapIntervalExt(display, window, i);
  81         else if (funSwapIntervalMesa)
  82                 funSwapIntervalMesa(i);
  83         else
  84                 assert(false && "At least one of glXSwapIntervalMESA, glXSwapIntervalEXT must be provided by the system");
  85 }