glfw/src/glx_context.c

//========================================================================
// GLFW - An OpenGL library
// Platform:    X11/GLX
// API version: 3.0
// WWW:         http://www.glfw.org/
//------------------------------------------------------------------------
// Copyright (c) 2002-2006 Marcus Geelnard
// Copyright (c) 2006-2010 Camilla Berglund <elmindreda@elmindreda.org>
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
//    claim that you wrote the original software. If you use this software
//    in a product, an acknowledgment in the product documentation would
//    be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such, and must not
//    be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source
//    distribution.
//
//========================================================================

#include "internal.h"

#include <string.h>
#include <stdlib.h>
#include <assert.h>


// This is the only glXGetProcAddress variant not declared by glxext.h
void (*glXGetProcAddressEXT(const GLubyte* procName))();


#ifndef GLXBadProfileARB
 #define GLXBadProfileARB 13
#endif


//========================================================================
// Thread local storage attribute macro
//========================================================================
#if defined(__GNUC__)
 #define _GLFW_TLS __thread
#else
 #define _GLFW_TLS
#endif


//========================================================================
// The X error code as provided to the X error handler
//========================================================================
static unsigned long _glfwErrorCode = Success;


//========================================================================
// The per-thread current context/window pointer
//========================================================================
static _GLFW_TLS _GLFWwindow* _glfwCurrentWindow = NULL;


//========================================================================
// Error handler used when creating a context with the GLX_ARB_create_context
// extension set
//========================================================================

static int errorHandler(Display *display, XErrorEvent* event)
{
    _glfwErrorCode = event->error_code;
    return 0;
}


//========================================================================
// Create the OpenGL context using legacy API
//========================================================================

static GLXContext createLegacyContext(_GLFWwindow* window,
                                      GLXFBConfig fbconfig,
                                      GLXContext share)
{
    if (_glfw.glx.SGIX_fbconfig)
    {
        return _glfw.glx.CreateContextWithConfigSGIX(_glfw.x11.display,
                                                     fbconfig,
                                                     GLX_RGBA_TYPE,
                                                     share,
                                                     True);
    }
    else
    {
        return glXCreateNewContext(_glfw.x11.display,
                                   fbconfig,
                                   GLX_RGBA_TYPE,
                                   share,
                                   True);
    }
}


//////////////////////////////////////////////////////////////////////////
//////                       GLFW internal API                      //////
//////////////////////////////////////////////////////////////////////////

//========================================================================
// Initialize GLX
//========================================================================

int _glfwInitContextAPI(void)
{
#ifdef _GLFW_DLOPEN_LIBGL
    int i;
    char* libGL_names[ ] =
    {
        "libGL.so",
        "libGL.so.1",
        "/usr/lib/libGL.so",
        "/usr/lib/libGL.so.1",
        NULL
    };

    for (i = 0;  libGL_names[i] != NULL;  i++)
    {
        _glfw.glx.libGL = dlopen(libGL_names[i], RTLD_LAZY | RTLD_GLOBAL);
        if (_glfw.glx.libGL)
            break;
    }

    if (!_glfw.glx.libGL)
    {
        _glfwInputError(GLFW_PLATFORM_ERROR, "GLX: Failed to find libGL");
        return GL_FALSE;
    }
#endif

    // Check if GLX is supported on this display
    if (!glXQueryExtension(_glfw.x11.display,
                           &_glfw.glx.errorBase,
                           &_glfw.glx.eventBase))
    {
        _glfwInputError(GLFW_API_UNAVAILABLE, "GLX: GLX support not found");
        return GL_FALSE;
    }

    if (!glXQueryVersion(_glfw.x11.display,
                         &_glfw.glx.versionMajor,
                         &_glfw.glx.versionMinor))
    {
        _glfwInputError(GLFW_API_UNAVAILABLE,
                        "GLX: Failed to query GLX version");
        return GL_FALSE;
    }

    if (_glfwPlatformExtensionSupported("GLX_EXT_swap_control"))
    {
        _glfw.glx.SwapIntervalEXT = (PFNGLXSWAPINTERVALEXTPROC)
            _glfwPlatformGetProcAddress("glXSwapIntervalEXT");

        if (_glfw.glx.SwapIntervalEXT)
            _glfw.glx.EXT_swap_control = GL_TRUE;
    }

    if (_glfwPlatformExtensionSupported("GLX_SGI_swap_control"))
    {
        _glfw.glx.SwapIntervalSGI = (PFNGLXSWAPINTERVALSGIPROC)
            _glfwPlatformGetProcAddress("glXSwapIntervalSGI");

        if (_glfw.glx.SwapIntervalSGI)
            _glfw.glx.SGI_swap_control = GL_TRUE;
    }

    if (_glfwPlatformExtensionSupported("GLX_MESA_swap_control"))
    {
        _glfw.glx.SwapIntervalMESA = (PFNGLXSWAPINTERVALMESAPROC)
            _glfwPlatformGetProcAddress("glXSwapIntervalMESA");

        if (_glfw.glx.SwapIntervalMESA)
            _glfw.glx.MESA_swap_control = GL_TRUE;
    }

    if (_glfwPlatformExtensionSupported("GLX_SGIX_fbconfig"))
    {
        _glfw.glx.GetFBConfigAttribSGIX = (PFNGLXGETFBCONFIGATTRIBSGIXPROC)
            _glfwPlatformGetProcAddress("glXGetFBConfigAttribSGIX");
        _glfw.glx.ChooseFBConfigSGIX = (PFNGLXCHOOSEFBCONFIGSGIXPROC)
            _glfwPlatformGetProcAddress("glXChooseFBConfigSGIX");
        _glfw.glx.CreateContextWithConfigSGIX = (PFNGLXCREATECONTEXTWITHCONFIGSGIXPROC)
            _glfwPlatformGetProcAddress("glXCreateContextWithConfigSGIX");
        _glfw.glx.GetVisualFromFBConfigSGIX = (PFNGLXGETVISUALFROMFBCONFIGSGIXPROC)
            _glfwPlatformGetProcAddress("glXGetVisualFromFBConfigSGIX");

        if (_glfw.glx.GetFBConfigAttribSGIX &&
            _glfw.glx.ChooseFBConfigSGIX &&
            _glfw.glx.CreateContextWithConfigSGIX &&
            _glfw.glx.GetVisualFromFBConfigSGIX)
        {
            _glfw.glx.SGIX_fbconfig = GL_TRUE;
        }
    }

    if (_glfwPlatformExtensionSupported("GLX_ARB_multisample"))
        _glfw.glx.ARB_multisample = GL_TRUE;

    if (_glfwPlatformExtensionSupported("GLX_ARB_framebuffer_sRGB"))
        _glfw.glx.ARB_framebuffer_sRGB = GL_TRUE;

    if (_glfwPlatformExtensionSupported("GLX_ARB_create_context"))
    {
        _glfw.glx.CreateContextAttribsARB = (PFNGLXCREATECONTEXTATTRIBSARBPROC)
            _glfwPlatformGetProcAddress("glXCreateContextAttribsARB");

        if (_glfw.glx.CreateContextAttribsARB)
            _glfw.glx.ARB_create_context = GL_TRUE;
    }

    if (_glfwPlatformExtensionSupported("GLX_ARB_create_context_robustness"))
        _glfw.glx.ARB_create_context_robustness = GL_TRUE;

    if (_glfwPlatformExtensionSupported("GLX_ARB_create_context_profile"))
        _glfw.glx.ARB_create_context_profile = GL_TRUE;

    if (_glfwPlatformExtensionSupported("GLX_EXT_create_context_es2_profile"))
        _glfw.glx.EXT_create_context_es2_profile = GL_TRUE;

    return GL_TRUE;
}


//========================================================================
// Terminate GLX
//========================================================================

void _glfwTerminateContextAPI(void)
{
    // Unload libGL.so if necessary
#ifdef _GLFW_DLOPEN_LIBGL
    if (_glfw.glx.libGL != NULL)
    {
        dlclose(_glfw.glx.libGL);
        _glfw.glx.libGL = NULL;
    }
#endif
}


//========================================================================
// Prepare for creation of the OpenGL context
//========================================================================

#define setGLXattrib(attribName, attribValue) \
{ \
    attribs[index++] = attribName; \
    attribs[index++] = attribValue; \
    assert(index < sizeof(attribs) / sizeof(attribs[0])); \
}

int _glfwCreateContext(_GLFWwindow* window,
                       const _GLFWwndconfig* wndconfig,
                       const _GLFWfbconfig* fbconfig)
{
    int attribs[40];
    GLXFBConfig* native;
    GLXContext share = NULL;

    if (wndconfig->share)
        share = wndconfig->share->glx.context;

    // Find a suitable GLXFBConfig
    {
        int count, index = 0;

        setGLXattrib(GLX_DOUBLEBUFFER, True);
        setGLXattrib(GLX_X_RENDERABLE, True);

        if (fbconfig->redBits)
            setGLXattrib(GLX_RED_SIZE, fbconfig->redBits);
        if (fbconfig->greenBits)
            setGLXattrib(GLX_GREEN_SIZE, fbconfig->greenBits);
        if (fbconfig->blueBits)
            setGLXattrib(GLX_BLUE_SIZE, fbconfig->blueBits);
        if (fbconfig->alphaBits)
            setGLXattrib(GLX_BLUE_SIZE, fbconfig->alphaBits);

        if (fbconfig->depthBits)
            setGLXattrib(GLX_DEPTH_SIZE, fbconfig->depthBits);
        if (fbconfig->stencilBits)
            setGLXattrib(GLX_STENCIL_SIZE, fbconfig->stencilBits);

        if (fbconfig->auxBuffers)
            setGLXattrib(GLX_AUX_BUFFERS, fbconfig->auxBuffers);

        if (fbconfig->accumRedBits)
            setGLXattrib(GLX_ACCUM_RED_SIZE, fbconfig->accumRedBits);
        if (fbconfig->accumGreenBits)
            setGLXattrib(GLX_ACCUM_GREEN_SIZE, fbconfig->accumGreenBits);
        if (fbconfig->accumBlueBits)
            setGLXattrib(GLX_ACCUM_BLUE_SIZE, fbconfig->accumBlueBits);
        if (fbconfig->accumAlphaBits)
            setGLXattrib(GLX_ACCUM_BLUE_SIZE, fbconfig->accumAlphaBits);

        if (fbconfig->stereo)
            setGLXattrib(GLX_STEREO, True);

        if (_glfw.glx.ARB_multisample)
        {
            if (fbconfig->samples)
            {
                setGLXattrib(GLX_SAMPLE_BUFFERS_ARB, 1);
                setGLXattrib(GLX_SAMPLES_ARB, fbconfig->samples);
            }
        }

        if (_glfw.glx.ARB_framebuffer_sRGB)
        {
            if (fbconfig->sRGB)
                setGLXattrib(GLX_FRAMEBUFFER_SRGB_CAPABLE_ARB, True);
        }

        setGLXattrib(None, None);

        if (_glfw.glx.SGIX_fbconfig)
        {
            native = _glfw.glx.ChooseFBConfigSGIX(_glfw.x11.display,
                                                  _glfw.x11.screen,
                                                  attribs,
                                                  &count);
        }
        else
        {
            native = glXChooseFBConfig(_glfw.x11.display,
                                       _glfw.x11.screen,
                                       attribs,
                                       &count);
        }

        if (native == NULL)
        {
            _glfwInputError(GLFW_PLATFORM_ERROR,
                            "GLX: Failed to find a suitable GLXFBConfig");
            return GL_FALSE;
        }
    }

    // Retrieve the corresponding visual
    if (_glfw.glx.SGIX_fbconfig)
    {
        window->glx.visual =
            _glfw.glx.GetVisualFromFBConfigSGIX(_glfw.x11.display, *native);
    }
    else
    {
        window->glx.visual = glXGetVisualFromFBConfig(_glfw.x11.display,
                                                      *native);
    }

    if (window->glx.visual == NULL)
    {
        XFree(native);

        _glfwInputError(GLFW_PLATFORM_ERROR,
                        "GLX: Failed to retrieve visual for GLXFBConfig");
        return GL_FALSE;
    }

    if (wndconfig->clientAPI == GLFW_OPENGL_ES_API)
    {
        if (!_glfw.glx.ARB_create_context ||
            !_glfw.glx.ARB_create_context_profile ||
            !_glfw.glx.EXT_create_context_es2_profile)
        {
            XFree(native);

            _glfwInputError(GLFW_VERSION_UNAVAILABLE,
                            "GLX: OpenGL ES requested but "
                            "GLX_EXT_create_context_es2_profile is unavailable");
            return GL_FALSE;
        }
    }

    if (wndconfig->glForward)
    {
        if (!_glfw.glx.ARB_create_context)
        {
            XFree(native);

            _glfwInputError(GLFW_VERSION_UNAVAILABLE,
                            "GLX: Forward compatibility requested but "
                            "GLX_ARB_create_context_profile is unavailable");
            return GL_FALSE;
        }
    }

    if (wndconfig->glProfile)
    {
        if (!_glfw.glx.ARB_create_context ||
            !_glfw.glx.ARB_create_context_profile)
        {
            XFree(native);

            _glfwInputError(GLFW_VERSION_UNAVAILABLE,
                            "GLX: An OpenGL profile requested but "
                            "GLX_ARB_create_context_profile is unavailable");
            return GL_FALSE;
        }
    }

    if (_glfw.glx.ARB_create_context)
    {
        int index = 0, mask = 0, flags = 0, strategy = 0;

        if (wndconfig->clientAPI == GLFW_OPENGL_API)
        {
            if (wndconfig->glForward)
                flags |= GLX_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB;

            if (wndconfig->glDebug)
                flags |= GLX_CONTEXT_DEBUG_BIT_ARB;

            if (wndconfig->glProfile)
            {
                if (wndconfig->glProfile == GLFW_OPENGL_CORE_PROFILE)
                    mask |= GLX_CONTEXT_CORE_PROFILE_BIT_ARB;
                else if (wndconfig->glProfile == GLFW_OPENGL_COMPAT_PROFILE)
                    mask |= GLX_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB;
            }
        }
        else
            mask |= GLX_CONTEXT_ES2_PROFILE_BIT_EXT;

        if (wndconfig->glRobustness != GLFW_NO_ROBUSTNESS)
        {
            if (_glfw.glx.ARB_create_context_robustness)
            {
                if (wndconfig->glRobustness == GLFW_NO_RESET_NOTIFICATION)
                    strategy = GLX_NO_RESET_NOTIFICATION_ARB;
                else if (wndconfig->glRobustness == GLFW_LOSE_CONTEXT_ON_RESET)
                    strategy = GLX_LOSE_CONTEXT_ON_RESET_ARB;

                flags |= GLX_CONTEXT_ROBUST_ACCESS_BIT_ARB;
            }
        }

        if (wndconfig->glMajor != 1 || wndconfig->glMinor != 0)
        {
            // NOTE: Only request an explicitly versioned context when
            // necessary, as explicitly requesting version 1.0 does not always
            // return the highest available version

            setGLXattrib(GLX_CONTEXT_MAJOR_VERSION_ARB, wndconfig->glMajor);
            setGLXattrib(GLX_CONTEXT_MINOR_VERSION_ARB, wndconfig->glMinor);
        }

        if (mask)
            setGLXattrib(GLX_CONTEXT_PROFILE_MASK_ARB, mask);

        if (flags)
            setGLXattrib(GLX_CONTEXT_FLAGS_ARB, flags);

        if (strategy)
            setGLXattrib(GLX_CONTEXT_RESET_NOTIFICATION_STRATEGY_ARB, strategy);

        setGLXattrib(None, None);

        // This is the only place we set an Xlib error handler, and we only do
        // it because glXCreateContextAttribsARB generates a BadMatch error if
        // the requested OpenGL version is unavailable (instead of a civilized
        // response like returning NULL)
        _glfwErrorCode = Success;
        XSetErrorHandler(errorHandler);

        window->glx.context =
            _glfw.glx.CreateContextAttribsARB(_glfw.x11.display,
                                              *native,
                                              share,
                                              True,
                                              attribs);

        // We are done, so unset the error handler again (see above)
        XSetErrorHandler(NULL);

        if (window->glx.context == NULL)
        {
            // HACK: This is a fallback for the broken Mesa implementation of
            // GLX_ARB_create_context_profile, which fails default 1.0 context
            // creation with a GLXBadProfileARB error in violation of the spec
            if (_glfwErrorCode == _glfw.glx.errorBase + GLXBadProfileARB &&
                wndconfig->clientAPI == GLFW_OPENGL_API &&
                wndconfig->glProfile == GLFW_OPENGL_NO_PROFILE &&
                wndconfig->glForward == GL_FALSE)
            {
                window->glx.context = createLegacyContext(window, *native, share);
            }
        }
    }
    else
        window->glx.context = createLegacyContext(window, *native, share);

    XFree(native);

    if (window->glx.context == NULL)
    {
        _glfwInputError(GLFW_PLATFORM_ERROR, "GLX: Failed to create context");
        return GL_FALSE;
    }

    return GL_TRUE;
}

#undef setGLXattrib


//========================================================================
// Destroy the OpenGL context
//========================================================================

void _glfwDestroyContext(_GLFWwindow* window)
{
    if (window->glx.visual)
    {
        XFree(window->glx.visual);
        window->glx.visual = NULL;
    }

    if (window->glx.context)
    {
        glXDestroyContext(_glfw.x11.display, window->glx.context);
        window->glx.context = NULL;
    }
}


//////////////////////////////////////////////////////////////////////////
//////                       GLFW platform API                      //////
//////////////////////////////////////////////////////////////////////////

//========================================================================
// Make the OpenGL context associated with the specified window current
//========================================================================

void _glfwPlatformMakeContextCurrent(_GLFWwindow* window)
{
    if (window)
    {
        glXMakeCurrent(_glfw.x11.display,
                       window->x11.handle,
                       window->glx.context);
    }
    else
        glXMakeCurrent(_glfw.x11.display, None, NULL);

    _glfwCurrentWindow = window;
}


//========================================================================
// Return the window object whose context is current
//========================================================================

_GLFWwindow* _glfwPlatformGetCurrentContext(void)
{
    return _glfwCurrentWindow;
}


//========================================================================
// Swap OpenGL buffers
//========================================================================

void _glfwPlatformSwapBuffers(_GLFWwindow* window)
{
    glXSwapBuffers(_glfw.x11.display, window->x11.handle);
}


//========================================================================
// Set double buffering swap interval
//========================================================================

void _glfwPlatformSwapInterval(int interval)
{
    _GLFWwindow* window = _glfwCurrentWindow;

    if (_glfw.glx.EXT_swap_control)
    {
        _glfw.glx.SwapIntervalEXT(_glfw.x11.display,
                                  window->x11.handle,
                                  interval);
    }
    else if (_glfw.glx.MESA_swap_control)
        _glfw.glx.SwapIntervalMESA(interval);
    else if (_glfw.glx.SGI_swap_control)
    {
        if (interval > 0)
            _glfw.glx.SwapIntervalSGI(interval);
    }
}


//========================================================================
// Check if an OpenGL extension is available at runtime
//========================================================================

int _glfwPlatformExtensionSupported(const char* extension)
{
    const GLubyte* extensions;

    // Get list of GLX extensions
    extensions = (const GLubyte*) glXQueryExtensionsString(_glfw.x11.display,
                                                           _glfw.x11.screen);
    if (extensions != NULL)
    {
        if (_glfwStringInExtensionString(extension, extensions))
            return GL_TRUE;
    }

    return GL_FALSE;
}


//========================================================================
// Get the function pointer to an OpenGL function
//========================================================================

GLFWglproc _glfwPlatformGetProcAddress(const char* procname)
{
    return _glfw_glXGetProcAddress((const GLubyte*) procname);
}