/*****************************************************************
 KWin - the KDE window manager
 This file is part of the KDE project.

Copyright (C) 2006 Rivo Laks <rivolaks@hot.ee>

You can Freely distribute this program under the GNU General Public
License. See the file "COPYING" for the exact licensing terms.
******************************************************************/

#include "glutils.h"

#include <dlfcn.h>


#define MAKE_GL_VERSION(major, minor, release)  ( ((major) << 16) | ((minor) << 8) | (release) )


namespace KWinInternal
{
// Variables
// GL version, use MAKE_GL_VERSION() macro for comparing with a specific version
static int glVersion;
// GLX version, use MAKE_GL_VERSION() macro for comparing with a specific version
static int glXVersion;
// List of all supported GL and GLX extensions
static QStringList glExtensions;
int glTextureUnitsCount;

// Function pointers
glXGetProcAddress_func glXGetProcAddress;
// GLX 1.3
glXQueryDrawable_func glXQueryDrawable;
// texture_from_pixmap extension functions
glXReleaseTexImageEXT_func glXReleaseTexImageEXT;
glXBindTexImageEXT_func glXBindTexImageEXT;
// glXCopySubBufferMESA
glXCopySubBuffer_func glXCopySubBuffer;
// video_sync extension functions
glXGetVideoSync_func glXGetVideoSync;
glXWaitVideoSync_func glXWaitVideoSync;
// glActiveTexture
glActiveTexture_func glActiveTexture;
// framebuffer_object extension functions
glIsRenderbuffer_func glIsRenderbuffer;
glBindRenderbuffer_func glBindRenderbuffer;
glDeleteRenderbuffers_func glDeleteRenderbuffers;
glGenRenderbuffers_func glGenRenderbuffers;
glRenderbufferStorage_func glRenderbufferStorage;
glGetRenderbufferParameteriv_func glGetRenderbufferParameteriv;
glIsFramebuffer_func glIsFramebuffer;
glBindFramebuffer_func glBindFramebuffer;
glDeleteFramebuffers_func glDeleteFramebuffers;
glGenFramebuffers_func glGenFramebuffers;
glCheckFramebufferStatus_func glCheckFramebufferStatus;
glFramebufferTexture1D_func glFramebufferTexture1D;
glFramebufferTexture2D_func glFramebufferTexture2D;
glFramebufferTexture3D_func glFramebufferTexture3D;
glFramebufferRenderbuffer_func glFramebufferRenderbuffer;
glGetFramebufferAttachmentParameteriv_func glGetFramebufferAttachmentParameteriv;
glGenerateMipmap_func glGenerateMipmap;


// Functions
static glXFuncPtr getProcAddress( const char* name )
    {
    glXFuncPtr ret = NULL;
    if( glXGetProcAddress != NULL )
        ret = glXGetProcAddress( ( const GLubyte* ) name );
    if( ret == NULL )
        ret = ( glXFuncPtr ) dlsym( RTLD_DEFAULT, name );
    return ret;
    }

void initGLX()
    {
    // Get GLX version
    int major, minor;
    glXQueryVersion( display(), &major, &minor );
    glXVersion = MAKE_GL_VERSION( major, minor, 0 );
    // Get list of supported GLX extensions. Simply add it to the list of OpenGL extensions.
    glExtensions += QString((const char*)glXQueryExtensionsString(
        display(), DefaultScreen( display()))).split(" ");

    // handle OpenGL extensions functions
    glXGetProcAddress = (glXGetProcAddress_func) getProcAddress( "glXGetProcAddress" );
    if( glXGetProcAddress == NULL )
        glXGetProcAddress = (glXGetProcAddress_func) getProcAddress( "glXGetProcAddressARB" );
    glXQueryDrawable = (glXQueryDrawable_func) getProcAddress( "glXQueryDrawable" );
    if( hasGLExtension( "GLX_EXT_texture_from_pixmap" ))
        {
        glXBindTexImageEXT = (glXBindTexImageEXT_func) getProcAddress( "glXBindTexImageEXT" );
        glXReleaseTexImageEXT = (glXReleaseTexImageEXT_func) getProcAddress( "glXReleaseTexImageEXT" );
        }
    else
        {
        glXBindTexImageEXT = NULL;
        glXReleaseTexImageEXT = NULL;
        }
    if( hasGLExtension( "GLX_MESA_copy_sub_buffer" ))
        glXCopySubBuffer = (glXCopySubBuffer_func) getProcAddress( "glXCopySubBufferMESA" );
    else
        glXCopySubBuffer = NULL;
    if( hasGLExtension( "GLX_SGI_video_sync" ))
        {
        glXGetVideoSync = (glXGetVideoSync_func) getProcAddress( "glXGetVideoSyncSGI" );
        glXWaitVideoSync = (glXWaitVideoSync_func) getProcAddress( "glXWaitVideoSyncSGI" );
        }
    else
        {
        glXGetVideoSync = NULL;
        glXWaitVideoSync = NULL;
        }
    }

void initGL()
    {
    // Get OpenGL version
    QString glversionstring = QString((const char*)glGetString(GL_VERSION));
    QStringList glversioninfo = glversionstring.left(glversionstring.indexOf(' ')).split('.');
    glVersion = MAKE_GL_VERSION(glversioninfo[0].toInt(), glversioninfo[1].toInt(),
                                    glversioninfo.count() > 2 ? glversioninfo[2].toInt() : 0);
    // Get list of supported OpenGL extensions
    glExtensions = QString((const char*)glGetString(GL_EXTENSIONS)).split(" ");

    // handle OpenGL extensions functions
    if( hasGLExtension( "GL_ARB_multitexture" ))
        {
        glActiveTexture = (glActiveTexture_func) getProcAddress( "glActiveTexture" );
        if( !glActiveTexture )
            glActiveTexture = (glActiveTexture_func) getProcAddress( "glActiveTextureARB" );
        // Get number of texture units
        glGetIntegerv(GL_MAX_TEXTURE_UNITS, &glTextureUnitsCount);
        }
    else
        {
        glActiveTexture = NULL;
        glTextureUnitsCount = 0;
        }
    if( hasGLExtension( "GL_EXT_framebuffer_object" ))
        {
        glIsRenderbuffer = (glIsRenderbuffer_func) getProcAddress( "glIsRenderbufferEXT" );
        glBindRenderbuffer = (glBindRenderbuffer_func) getProcAddress( "glBindRenderbufferEXT" );
        glDeleteRenderbuffers = (glDeleteRenderbuffers_func) getProcAddress( "glDeleteRenderbuffersEXT" );
        glGenRenderbuffers = (glGenRenderbuffers_func) getProcAddress( "glGenRenderbuffersEXT" );

        glRenderbufferStorage = (glRenderbufferStorage_func) getProcAddress( "glRenderbufferStorageEXT" );

        glGetRenderbufferParameteriv = (glGetRenderbufferParameteriv_func) getProcAddress( "glGetRenderbufferParameterivEXT" );

        glIsFramebuffer = (glIsFramebuffer_func) getProcAddress( "glIsFramebufferEXT" );
        glBindFramebuffer = (glBindFramebuffer_func) getProcAddress( "glBindFramebufferEXT" );
        glDeleteFramebuffers = (glDeleteFramebuffers_func) getProcAddress( "glDeleteFramebuffersEXT" );
        glGenFramebuffers = (glGenFramebuffers_func) getProcAddress( "glGenFramebuffersEXT" );

        glCheckFramebufferStatus = (glCheckFramebufferStatus_func) getProcAddress( "glCheckFramebufferStatusEXT" );

        glFramebufferTexture1D = (glFramebufferTexture1D_func) getProcAddress( "glFramebufferTexture1DEXT" );
        glFramebufferTexture2D = (glFramebufferTexture2D_func) getProcAddress( "glFramebufferTexture2DEXT" );
        glFramebufferTexture3D = (glFramebufferTexture3D_func) getProcAddress( "glFramebufferTexture3DEXT" );

        glFramebufferRenderbuffer = (glFramebufferRenderbuffer_func) getProcAddress( "glFramebufferRenderbufferEXT" );

        glGetFramebufferAttachmentParameteriv = (glGetFramebufferAttachmentParameteriv_func) getProcAddress( "glGetFramebufferAttachmentParameterivEXT" );

        glGenerateMipmap = (glGenerateMipmap_func) getProcAddress( "glGenerateMipmapEXT" );
        }
    else
        {
        glIsRenderbuffer = NULL;
        glBindRenderbuffer = NULL;
        glDeleteRenderbuffers = NULL;
        glGenRenderbuffers = NULL;
        glRenderbufferStorage = NULL;
        glGetRenderbufferParameteriv = NULL;
        glIsFramebuffer = NULL;
        glBindFramebuffer = NULL;
        glDeleteFramebuffers = NULL;
        glGenFramebuffers = NULL;
        glCheckFramebufferStatus = NULL;
        glFramebufferTexture1D = NULL;
        glFramebufferTexture2D = NULL;
        glFramebufferTexture3D = NULL;
        glFramebufferRenderbuffer = NULL;
        glGetFramebufferAttachmentParameteriv = NULL;
        glGenerateMipmap = NULL;
        }
    }

bool hasGLVersion(int major, int minor, int release)
    {
    return glVersion >= MAKE_GL_VERSION(major, minor, release);
    }

bool hasGLXVersion(int major, int minor, int release)
    {
    return glXVersion >= MAKE_GL_VERSION(major, minor, release);
    }

bool hasGLExtension(const QString& extension)
    {
    return glExtensions.contains(extension);
    }

} // namespace