OpenGL: Add code generator for OpenGL enabler classes

This patch provides a code generator that can be executed offline
to generate a few classes for enhancing Qt's support for OpenGL.
The generated code effectively provides all the benefits of GLEW
in its multi-context form but for all platforms and even for ES2.

The code generator takes as input the official Khronos gl.spec
specification and gl.tm typemap files. These provide all of the
information required to create the OpenGL Desktop related classes.
The classes for ES2 are hand-crafted as no similar spec files have
been published.

The generated code supports all OpenGL extensions listed in the
Khronos registry for both Desktop OpenGL and ES 2.

There is a helper factory class generated which are used by
QOpenGLContext::versionFunctions().

This allows code like the following to be written:

QOpenGLFunctions_3_3_Core* m_funcs = 0;
m_funcs = m_context->versionFunctions<QOpenGLFunctions_3_3_Core>();
if (!m_funcs) {
    qWarning() << "Could not obtain required OpenGL context version";
    exit(1);
}

if (!m_funcs->initializeOpenGLFunctions()) {
    qWarning() << "Failed to resolve entry points";
    exit(2);
}

// Get an extension object
QOpenGLExtension_ARB_draw_buffers* ext = 0;
if (m_context->hasExtension("GL_ARB_draw_buffers")) {
    ext = new QOpenGLExtension_ARB_draw_buffers();
    ext->initializeOpenGLFunctions(m_context);
}

Such usage will allow much easier and rigorous use of features in
modern OpenGL and extensions both in Qt itself and by users of Qt.

Follow-up patches will import the generated files and then use
these to reinstate OpenGL geometry shaders, add tessellation
shaders, and other OpenGL constructs.

Change-Id: Id0172e8aa1fd57eb4e6979a96d10fb5a34826426
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>
Reviewed-by: James Turner <james.turner@kdab.com>

1 files changed, 208 insertions, 0 deletions

diff --git a/util/glgen/qopenglextensions.h.header b/util/glgen/qopenglextensions.h.header
new file mode 100644
index 0000000000..89e248fc33
--- /dev/null
+++ b/util/glgen/qopenglextensions.h.header
@@ -0,0 +1,208 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Klaralvdalens Datakonsult AB (KDAB)
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+**
+** This file was generated by glgen version 0.1
+** Command line was: glgen
+**
+** glgen is Copyright (C) 2013 Klaralvdalens Datakonsult AB (KDAB)
+**
+** This is an auto-generated file.
+** Do not edit! All changes made to it will be lost.
+**
+****************************************************************************/
+
+#ifndef QOPENGLEXTENSIONS_H
+#define QOPENGLEXTENSIONS_H
+
+#ifndef QT_NO_OPENGL
+
+#include <QtCore/QtGlobal>
+#include <QtGui/qopengl.h>
+
+class QOpenGLContext;
+
+QT_BEGIN_NAMESPACE
+
+#if 0
+// silence syncqt warnings
+#pragma qt_class(QOpenGLExtensions)
+#pragma qt_sync_stop_processing
+#endif
+
+#if !defined(QT_OPENGL_ES_2)
+// This block is copied from glext.h and defines the types needed by
+// a few extension classes. This may need updating in glgen when a new
+// OpenGL release is made and this file is regenerated.
+
+#include <stddef.h>
+#ifndef GL_VERSION_2_0
+/* GL type for program/shader text */
+typedef char GLchar;
+#endif
+
+#ifndef GL_VERSION_1_5
+/* GL types for handling large vertex buffer objects */
+typedef ptrdiff_t GLintptr;
+typedef ptrdiff_t GLsizeiptr;
+#endif
+
+#ifndef GL_ARB_vertex_buffer_object
+/* GL types for handling large vertex buffer objects */
+typedef ptrdiff_t GLintptrARB;
+typedef ptrdiff_t GLsizeiptrARB;
+#endif
+
+#ifndef GL_ARB_shader_objects
+/* GL types for program/shader text and shader object handles */
+typedef char GLcharARB;
+typedef unsigned int GLhandleARB;
+#endif
+
+/* GL type for "half" precision (s10e5) float data in host memory */
+#ifndef GL_ARB_half_float_pixel
+typedef unsigned short GLhalfARB;
+#endif
+
+#ifndef GL_NV_half_float
+typedef unsigned short GLhalfNV;
+#endif
+
+#ifndef GLEXT_64_TYPES_DEFINED
+/* This code block is duplicated in glxext.h, so must be protected */
+#define GLEXT_64_TYPES_DEFINED
+/* Define int32_t, int64_t, and uint64_t types for UST/MSC */
+/* (as used in the GL_EXT_timer_query extension). */
+#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L
+#include <inttypes.h>
+#elif defined(__sun__) || defined(__digital__)
+#include <inttypes.h>
+#if defined(__STDC__)
+#if defined(__arch64__) || defined(_LP64)
+typedef long int int64_t;
+typedef unsigned long int uint64_t;
+#else
+typedef long long int int64_t;
+typedef unsigned long long int uint64_t;
+#endif /* __arch64__ */
+#endif /* __STDC__ */
+#elif defined( __VMS ) || defined(__sgi)
+#include <inttypes.h>
+#elif defined(__SCO__) || defined(__USLC__)
+#include <stdint.h>
+#elif defined(__UNIXOS2__) || defined(__SOL64__)
+typedef long int int32_t;
+typedef long long int int64_t;
+typedef unsigned long long int uint64_t;
+#elif defined(_WIN32) && defined(__GNUC__)
+#include <stdint.h>
+#elif defined(_WIN32)
+typedef __int32 int32_t;
+typedef __int64 int64_t;
+typedef unsigned __int64 uint64_t;
+#else
+/* Fallback if nothing above works */
+#include <inttypes.h>
+#endif
+#endif
+
+#ifndef GL_EXT_timer_query
+typedef int64_t GLint64EXT;
+typedef uint64_t GLuint64EXT;
+#endif
+
+#ifndef GL_ARB_sync
+typedef int64_t GLint64;
+typedef uint64_t GLuint64;
+typedef struct __GLsync *GLsync;
+#endif
+
+#ifndef GL_ARB_cl_event
+/* These incomplete types let us declare types compatible with OpenCL's cl_context and cl_event */
+struct _cl_context;
+struct _cl_event;
+#endif
+
+#ifndef GL_ARB_debug_output
+typedef void (APIENTRY *GLDEBUGPROCARB)(GLenum source,GLenum type,GLuint id,GLenum severity,GLsizei length,const GLchar *message,GLvoid *userParam);
+#endif
+
+#ifndef GL_AMD_debug_output
+typedef void (APIENTRY *GLDEBUGPROCAMD)(GLuint id,GLenum category,GLenum severity,GLsizei length,const GLchar *message,GLvoid *userParam);
+#endif
+
+#ifndef GL_KHR_debug
+typedef void (APIENTRY *GLDEBUGPROC)(GLenum source,GLenum type,GLuint id,GLenum severity,GLsizei length,const GLchar *message,GLvoid *userParam);
+#endif
+
+#ifndef GL_NV_vdpau_interop
+typedef GLintptr GLvdpauSurfaceNV;
+#endif
+
+// End of block copied from glext.h
+#endif
+
+struct QOpenGLFunctionsPrivate;
+
+class QAbstractOpenGLExtensionPrivate
+{
+public:
+    QAbstractOpenGLExtensionPrivate() : initialized(false) {}
+    bool initialized;
+};
+
+class QAbstractOpenGLExtension
+{
+public:
+    virtual ~QAbstractOpenGLExtension();
+
+    virtual bool initializeOpenGLFunctions();
+
+    Q_DECLARE_PRIVATE(QAbstractOpenGLExtension)
+
+protected:
+    bool isInitialized() const;
+
+    QAbstractOpenGLExtension() {}
+    QAbstractOpenGLExtension(QAbstractOpenGLExtensionPrivate &dd) : d_ptr(&dd) {}
+    QAbstractOpenGLExtensionPrivate *d_ptr;
+};
+
+#if !defined(QT_OPENGL_ES_2)
+