glxbackend.cpp

   1 /* gltest - small OpenGL tearing test program
   2  * Copyright (C) 2012-2013 Ralf Jung <post@ralfj.de>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  17  */
  18
  19 #include "glxbackend.h"
  20 #include "glutil.h"
  21
  22 #include <stdio.h>
  23 #include <assert.h>
  24 #include <GL/glxext.h>
  25 #include <string>
  26
  27 #if !defined(CON_GL1) && !defined(CON_GL3)
  28 #error "Valid GL contexts for GLX are: GL1, GL3"
  29 #endif
  30
  31 // attributes for a double buffered framebuffer in RGBA format with at least 4 bits per color
  32 static int configAttribs[] =
  33 {
  34         GLX_RENDER_TYPE, GLX_RGBA_BIT,
  35         GLX_DOUBLEBUFFER, True,
  36         GLX_RED_SIZE, 4,
  37         GLX_GREEN_SIZE, 4,
  38         GLX_BLUE_SIZE, 4,
  39         None
  40 };
  41
  42 #ifdef CON_GL3
  43 // attributes for a GL3 context
  44 static int contextAttribs[] =
  45 {
  46         GLX_CONTEXT_MAJOR_VERSION_ARB,               3,
  47         GLX_CONTEXT_MINOR_VERSION_ARB,               0,
  48         GLX_CONTEXT_FLAGS_ARB,                       GLX_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB,
  49         None
  50 };
  51 #endif
  52
  53 VisualID GLXBackend::initialize(Display *display)
  54 {
  55         if (this->display == NULL) { // this implies that the context is also unitialized
  56                 this->display = display;
  57                 // debugging: show version information
  58                 int glxMajor, glxMinor;
  59                 glXQueryVersion(display, &glxMajor, &glxMinor);
  60                 printf("Using GLX version: %d.%d\n", glxMajor, glxMinor);
  61                 if (glxMajor == 1 && glxMinor < 3) {
  62                         // glXChooseFBConfig and glXCreateNewContext require GLX 1.3
  63                         die("Need at least GLX 1.3 to function properly\n");
  64                 }
  65                 // check for extension-based functions
  66                 funSwapIntervalMesa = (PFNGLXSWAPINTERVALMESAPROC)resolveGLXFunction("GLX_MESA_swap_control", "glXSwapIntervalMESA");
  67                 funSwapIntervalExt = (PFNGLXSWAPINTERVALEXTPROC)resolveGLXFunction("GLX_EXT_swap_control", "glXSwapIntervalEXT");
  68                 funCreateContextAttribsARB = (PFNGLXCREATECONTEXTATTRIBSARBPROC)resolveGLXFunction("GLX_ARB_create_context", "glXCreateContextAttribsARB");
  69                 // get the first usable framebuffer configuration
  70                 int count = 0;
  71                 GLXFBConfig *configs = glXChooseFBConfig(display, DefaultScreen(display), configAttribs, &count);
  72                 if (count < 1) {
  73                         die("Failed to choose framebuffer configuration\n");
  74                 }
  75                 config = configs[0];
  76                 XFree(configs);
  77         }
  78         // return visual ID
  79         XVisualInfo *vi = glXGetVisualFromFBConfig(display, config);
  80         VisualID visualid = vi->visualid;
  81         XFree(vi);
  82         return visualid;
  83 }
  84
  85 bool GLXBackend::haveGLXExtension(const std::string &name)
  86 {
  87         assert(display != NULL);
  88         std::string extensions = glXQueryExtensionsString(display, DefaultScreen(display));
  89         return (std::string(" "+extensions+" ").find(" "+name+" ") != std::string::npos);
  90 }
  91
  92 T_proc GLXBackend::resolveGLXFunction(const char *extension, const char *function)
  93 {
  94         if (!haveGLXExtension(extension)) return NULL;
  95         T_proc f = glXGetProcAddress((const GLubyte*)function);
  96         if (f)
  97                 printf("%s is supported, using it for %s\n", extension, function);
  98         return f;
  99 }
 100
 101 void GLXBackend::createContext(Window window)
 102 {
 103         assert(display != NULL && context == None);
 104         this->window = window;
 105         // create context with that window
 106 #ifdef CON_GL1
 107         context = glXCreateNewContext(display, config, GLX_RGBA_TYPE, NULL, GL_TRUE);
 108 #else
 109         if (!funCreateContextAttribsARB) {
 110                 die("Cannot create GL3 context: GLX_ARB_create_context not supported\n");
 111         }
 112         context = funCreateContextAttribsARB(display, config, NULL, GL_TRUE, contextAttribs);
 113 #endif
 114         if (!context) {
 115                 die("Error creating context\n");
 116         }
 117         glXMakeCurrent(display, window, context);
 118         assert(glXIsDirect(display, context));
 119         printf("Using GL version: %s\n", glGetString(GL_VERSION));
 120         // initialise GL utilities
 121         resolveFunctionPointers((T_glGetProcAddress)glXGetProcAddress);
 122 }
 123
 124 GLXBackend::~GLXBackend()
 125 {
 126         if (display != NULL) {
 127                 if (context != None) {
 128                         glXMakeCurrent(display, None, NULL);
 129                         glXDestroyContext(display, context);
 130                 }
 131         }
 132 }
 133
 134 void GLXBackend::swapBuffers() const
 135 {
 136         assert(context != None); // this implies the display is also initialized
 137         glXSwapBuffers(display, window);
 138 }
 139
 140 void GLXBackend::setSwapInterval(int i) const
 141 {
 142         assert(context != None);
 143         // check if swap interval value is supported
 144         if (i < 0) {
 145                 die("Cannot set swap interval to %d, must not be negative\n", i);
 146         }
 147         // set it
 148         if (funSwapIntervalExt)
 149                 funSwapIntervalExt(display, window, i);
 150         else if (funSwapIntervalMesa)
 151                 funSwapIntervalMesa(i);
 152         else {
 153                 die("At least one of GLX_EXT_swap_control, GLX_MESA_swap_control must be supported by the system\n");
 154         }
 155 }