Modernize the OpenGL examples

Change them to use QOpenGLWidget and QOpenGLTexture.
Advocate also the usage of VBOs.

Hopeless examples, that rely on the fixed pipeline and will
not compile or work in ES and dynamic builds, are moved to
a "legacy" directory. The documentation pages for these are
removed. This long due change avoids the confusion newcomers
experience when trying to get started with Qt 5 and OpenGL.

hellowindow's behavior is changed to open a single window only
by default. The old default behavior, that opened three windows
on platforms that supported both MultipleWindows & ThreadedOpenGL,
can be requested by passing --multiple. --single is removed since it
is the default now. This plays much nicer with drivers that have
issues with threading.

In addition, say hello to hellogl2.

This is the old hellogl example updated to use QOpenGLWidget and
OpenGL 2. It also has a mainwindow with multiple (un)dockable widgets
containing the OpenGL widgets. This helps testing the behavior when
the top-level of the QOpenGLWidget changes and provides a very
important example of how to do proper resource management in this case.
(must use aboutToBeDestroyed() of the context, since the context goes
away and is replaced by a new one on every dock/undock)

As a bonus, the logo is now real 3D, no more orthographic nonsense.

Launch with --multisample to request 4x MSAA.

Launch with --coreprofile to request 3.2 Core. In this particular example
the shaders are present in both versions and there is a VAO so the application
is functional with core profile contexts.

Change-Id: Id780a80cb0708ef164cc172450ed74050f065596
Reviewed-by: Gunnar Sletta <gunnar.sletta@jollamobile.com>

1 files changed, 22 insertions, 24 deletions

diff --git a/examples/opengl/cube/geometryengine.cpp b/examples/opengl/cube/geometryengine.cpp
index 0a34213084..618a080c37 100644
--- a/examples/opengl/cube/geometryengine.cpp
+++ b/examples/opengl/cube/geometryengine.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
 ** Contact: http://www.qt-project.org/legal
 **
 ** This file is part of the QtCore module of the Qt Toolkit.
@@ -49,29 +49,27 @@ struct VertexData
     QVector2D texCoord;
 };
 
+//! [0]
 GeometryEngine::GeometryEngine()
+    : indexBuf(QOpenGLBuffer::IndexBuffer)
 {
-}
-
-GeometryEngine::~GeometryEngine()
-{
-    glDeleteBuffers(2, vboIds);
-}
-
-void GeometryEngine::init()
-{
-    initializeGLFunctions();
+    initializeOpenGLFunctions();
 
-//! [0]
     // Generate 2 VBOs
-    glGenBuffers(2, vboIds);
-
-//! [0]
+    arrayBuf.create();
+    indexBuf.create();
 
     // Initializes cube geometry and transfers it to VBOs
     initCubeGeometry();
 }
 
+GeometryEngine::~GeometryEngine()
+{
+    arrayBuf.destroy();
+    indexBuf.destroy();
+}
+//! [0]
+
 void GeometryEngine::initCubeGeometry()
 {
     // For cube we would need only 8 vertices but we have to
@@ -133,21 +131,21 @@ void GeometryEngine::initCubeGeometry()
 
 //! [1]
     // Transfer vertex data to VBO 0
-    glBindBuffer(GL_ARRAY_BUFFER, vboIds[0]);
-    glBufferData(GL_ARRAY_BUFFER, 24 * sizeof(VertexData), vertices, GL_STATIC_DRAW);
+    arrayBuf.bind();
+    arrayBuf.allocate(vertices, 24 * sizeof(VertexData));
 
     // Transfer index data to VBO 1
-    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, vboIds[1]);
-    glBufferData(GL_ELEMENT_ARRAY_BUFFER, 34 * sizeof(GLushort), indices, GL_STATIC_DRAW);
+    indexBuf.bind();
+    indexBuf.allocate(indices, 34 * sizeof(GLushort));
 //! [1]
 }
 
 //! [2]
-void GeometryEngine::drawCubeGeometry(QGLShaderProgram *program)
+void GeometryEngine::drawCubeGeometry(QOpenGLShaderProgram *program)
 {
     // Tell OpenGL which VBOs to use
-    glBindBuffer(GL_ARRAY_BUFFER, vboIds[0]);
-    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, vboIds[1]);
+    arrayBuf.bind();
+    indexBuf.bind();
 
     // Offset for position
     quintptr offset = 0;
@@ -155,7 +153,7 @@ void GeometryEngine::drawCubeGeometry(QGLShaderProgram *program)
     // Tell OpenGL programmable pipeline how to locate vertex position data
     int vertexLocation = program->attributeLocation("a_position");
     program->enableAttributeArray(vertexLocation);
-    glVertexAttribPointer(vertexLocation, 3, GL_FLOAT, GL_FALSE, sizeof(VertexData), (const void *)offset);
+    program->setAttributeBuffer(vertexLocation, GL_FLOAT, offset, 3, sizeof(VertexData));
 
     // Offset for texture coordinate
     offset += sizeof(QVector3D);
@@ -163,7 +161,7 @@ void GeometryEngine::drawCubeGeometry(QGLShaderProgram *program)
     // Tell OpenGL programmable pipeline how to locate vertex texture coordinate data
     int texcoordLocation = program->attributeLocation("a_texcoord");
     program->enableAttributeArray(texcoordLocation);
-    glVertexAttribPointer(texcoordLocation, 2, GL_FLOAT, GL_FALSE, sizeof(VertexData), (const void *)offset);
+    program->setAttributeBuffer(texcoordLocation, GL_FLOAT, offset, 2, sizeof(VertexData));
 
     // Draw cube geometry using indices from VBO 1
     glDrawElements(GL_TRIANGLE_STRIP, 34, GL_UNSIGNED_SHORT, 0);