glxbackend.cpp

   1 #include "glxbackend.h"
   2
   3 #include <stdio.h>
   4 #include <assert.h>
   5 #include <stdlib.h>
   6 #include <GL/glxext.h>
   7 #include <string>
   8
   9 /* attributes for a double buffered visual in RGBA format with at least
  10 * 4 bits per color */
  11 static int attrList[] =
  12 {
  13         GLX_RGBA, GLX_DOUBLEBUFFER,
  14         GLX_RED_SIZE, 4,
  15         GLX_GREEN_SIZE, 4,
  16         GLX_BLUE_SIZE, 4,
  17         None
  18 };
  19
  20 VisualID GLXBackend::initialize(Display *display)
  21 {
  22         if (this->display == NULL) { // this implies that the context is also unitialized
  23                 this->display = display;
  24                 // debugging: show version information
  25                 int glxMajor, glxMinor;
  26                 glXQueryVersion(display, &glxMajor, &glxMinor);
  27                 printf("Using GLX version %d.%d\n", glxMajor, glxMinor);
  28                 // check for swap control functions
  29                 const char *extensions = glXQueryExtensionsString(display, DefaultScreen(display));
  30                 if (std::string(extensions).find("GLX_MESA_swap_control") != std::string::npos) {
  31                         funSwapIntervalMesa = (PFNGLXSWAPINTERVALMESAPROC)glXGetProcAddress((const GLubyte*)"glXSwapIntervalMESA");
  32                         if (funSwapIntervalMesa) printf("glXSwapIntervalMESA is present\n");
  33                 }
  34                 else {
  35                         funSwapIntervalMesa = 0;
  36                 }
  37                 if (std::string(extensions).find("GLX_EXT_swap_control") != std::string::npos) {
  38                         funSwapIntervalExt = (PFNGLXSWAPINTERVALEXTPROC)glXGetProcAddress((const GLubyte*)"glXSwapIntervalEXT");
  39                         if (funSwapIntervalExt) printf("glXSwapIntervalEXT is present\n");
  40                 }
  41                 else {
  42                         funSwapIntervalExt = 0;
  43                 }
  44                 // get the visual
  45                 vi = glXChooseVisual(display, DefaultScreen(display), attrList);
  46         }
  47         return vi->visualid;
  48 }
  49
  50 void GLXBackend::createContext(Window window)
  51 {
  52         assert(display != NULL && context == None);
  53         this->window = window;
  54         // create context with that window
  55         context = glXCreateContext(display, vi, 0, GL_TRUE);
  56         glXMakeCurrent(display, window, context);
  57         assert(glXIsDirect(display, context));
  58 }
  59
  60 GLXBackend::~GLXBackend()
  61 {
  62         if (display != NULL) {
  63                 if (context != None) {
  64                         glXMakeCurrent(display, None, NULL);
  65                         glXDestroyContext(display, context);
  66                 }
  67                 XFree(vi);
  68         }
  69 }
  70
  71 void GLXBackend::swapBuffers() const
  72 {
  73         assert(context != None); // this implies the display is also initialized
  74         glXSwapBuffers(display, window);
  75 }
  76
  77 void GLXBackend::setSwapInterval(int i) const
  78 {
  79         assert(context != None);
  80         if (funSwapIntervalExt)
  81                 funSwapIntervalExt(display, window, i);
  82         else if (funSwapIntervalMesa)
  83                 funSwapIntervalMesa(i);
  84         else {
  85                 fprintf(stderr, "At least one of glXSwapIntervalMESA, glXSwapIntervalEXT must be provided by the system\n");
  86                 abort();
  87         }
  88 }