Fix the OpenGL textures example for Qt 6

In Qt, the example has been ported to use modern Open GL (shaders).
While this can still be done, it is worthwhile to also
show the use of QOpenGLVersionFunctionsFactory for legacy Open GL code.

Change-Id: I5ba434bd5324bde1eec3075689f08c770329ce00
Reviewed-by: Christian Tismer <tismer@stackless.com>
(cherry picked from commit 3020e8a7628f200dd511c1ee6c4745417195960a)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 88 insertions, 70 deletions

diff --git a/examples/opengl/textures/textures.py b/examples/opengl/textures/textures.py
index cbefe41d6..eadf25185 100644
--- a/examples/opengl/textures/textures.py
+++ b/examples/opengl/textures/textures.py
@@ -2,7 +2,7 @@
 ############################################################################
 ##
 ## Copyright (C) 2013 Riverbank Computing Limited.
-## Copyright (C) 2016 The Qt Company Ltd.
+## Copyright (C) 2022 The Qt Company Ltd.
 ## Contact: http://www.qt.io/licensing/
 ##
 ## This file is part of the Qt for Python examples of the Qt Toolkit.
@@ -40,18 +40,24 @@
 ##
 ############################################################################
 
-"""PySide6 port of the opengl/textures example from Qt v5.x"""
+"""PySide6 port of the opengl/textures example from Qt v6.x showing the use
+   of legacy OpenGL functions with QOpenGLVersionFunctionsFactory."""
 
 import sys
-from PySide6 import QtCore, QtGui, QtWidgets, QtOpenGL
+from PySide6.QtCore import QPoint, QSize, Qt, QTimer, Signal
+from PySide6.QtGui import QColor, QImage, QSurfaceFormat
+from PySide6.QtWidgets import QApplication, QGridLayout, QMessageBox, QWidget
+from PySide6.QtOpenGL import (QOpenGLTexture, QOpenGLVersionFunctionsFactory,
+                              QOpenGLVersionProfile)
+from PySide6.QtOpenGLWidgets import QOpenGLWidget
 
 try:
-    from OpenGL.GL import *
+    from OpenGL import GL
 except ImportError:
-    app = QtWidgets.QApplication(sys.argv)
-    messageBox = QtWidgets.QMessageBox(QtWidgets.QMessageBox.Critical, "OpenGL textures",
-                                       "PyOpenGL must be installed to run this example.",
-                                       QtWidgets.QMessageBox.Close)
+    app = QApplication(sys.argv)
+    messageBox = QMessageBox(QMessageBox.Critical, "OpenGL textures",
+                             "PyOpenGL must be installed to run this example.",
+                             QMessageBox.Close)
     messageBox.setDetailedText("Run:\npip install PyOpenGL PyOpenGL_accelerate")
     messageBox.exec()
     sys.exit(1)
@@ -59,7 +65,7 @@ except ImportError:
 import textures_rc
 
 
-class GLWidget(QtOpenGL.QGLWidget):
+class GLWidget(QOpenGLWidget):
     sharedObject = 0
     refCount = 0
 
@@ -72,118 +78,131 @@ class GLWidget(QtOpenGL.QGLWidget):
         ( ( -1, -1, +1 ), ( +1, -1, +1 ), ( +1, +1, +1 ), ( -1, +1, +1 ) )
     )
 
-    clicked = QtCore.Signal()
+    clicked = Signal()
 
-    def __init__(self, parent, shareWidget):
-        QtOpenGL.QGLWidget.__init__(self, parent, shareWidget)
+    def __init__(self, parent):
+        super().__init__(parent)
 
-        self.clearColor = QtCore.Qt.black
+        self.clearColor = Qt.black
         self.xRot = 0
         self.yRot = 0
         self.zRot = 0
-        self.clearColor = QtGui.QColor()
-        self.lastPos = QtCore.QPoint()
+        self.clearColor = QColor()
+        self.lastPos = QPoint()
+        self.funcs = None
 
     def freeGLResources(self):
         GLWidget.refCount -= 1
         if GLWidget.refCount == 0:
             self.makeCurrent()
-            glDeleteLists(self.__class__.sharedObject, 1)
+            self.funcs.glDeleteLists(self.__class__.sharedObject, 1)
 
     def minimumSizeHint(self):
-        return QtCore.QSize(50, 50)
+        return QSize(50, 50)
 
     def sizeHint(self):
-        return QtCore.QSize(200, 200)
+        return QSize(200, 200)
 
     def rotateBy(self, xAngle, yAngle, zAngle):
         self.xRot = (self.xRot + xAngle) % 5760
         self.yRot = (self.yRot + yAngle) % 5760
         self.zRot = (self.zRot + zAngle) % 5760
-        self.updateGL()
+        self.update()
 
     def setClearColor(self, color):
         self.clearColor = color
-        self.updateGL()
+        self.update()
 
     def initializeGL(self):
+        profile = QOpenGLVersionProfile()
+        profile.setVersion(3, 2)
+        profile.setProfile(QSurfaceFormat.CompatibilityProfile)
+        self.funcs = QOpenGLVersionFunctionsFactory.get(profile)
+        self.funcs.initializeOpenGLFunctions()
+
         if not GLWidget.sharedObject:
             self.textures = []
             for i in range(6):
-                self.textures.append(self.bindTexture(QtGui.QPixmap(f":/images/side{i + 1}.png")))
+                image = QImage(f":/images/side{i + 1}.png")
+                self.textures.append(QOpenGLTexture(image))
             GLWidget.sharedObject = self.makeObject()
         GLWidget.refCount += 1
 
-        glEnable(GL_DEPTH_TEST)
-        glEnable(GL_CULL_FACE)
-        glEnable(GL_TEXTURE_2D)
+        self.funcs.glEnable(GL.GL_DEPTH_TEST)
+        self.funcs.glEnable(GL.GL_CULL_FACE)
+        self.funcs.glEnable(GL.GL_TEXTURE_2D)
 
     def paintGL(self):
-        self.qglClearColor(self.clearColor)
-        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
-        glLoadIdentity()
-        glTranslated(0.0, 0.0, -10.0)
-        glRotated(self.xRot / 16.0, 1.0, 0.0, 0.0)
-        glRotated(self.yRot / 16.0, 0.0, 1.0, 0.0)
-        glRotated(self.zRot / 16.0, 0.0, 0.0, 1.0)
-        glCallList(GLWidget.sharedObject)
+        self.funcs.glClearColor(self.clearColor.red(), self.clearColor.green(),
+                                self.clearColor.blue(), 1)
+        self.funcs.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT)
+        self.funcs.glLoadIdentity()
+        self.funcs.glTranslated(0.0, 0.0, -10.0)
+        self.funcs.glRotated(self.xRot / 16.0, 1.0, 0.0, 0.0)
+        self.funcs.glRotated(self.yRot / 16.0, 0.0, 1.0, 0.0)
+        self.funcs.glRotated(self.zRot / 16.0, 0.0, 0.0, 1.0)
+        self.funcs.glCallList(GLWidget.sharedObject)
 
     def resizeGL(self, width, height):
         side = min(width, height)
-        glViewport(int((width - side) / 2), int((height - side) / 2), side, side)
+        x = int((width - side) / 2)
+        y = int((height - side) / 2)
+        self.funcs.glViewport(x, y, side, side)
 
-        glMatrixMode(GL_PROJECTION)
-        glLoadIdentity()
-        glOrtho(-0.5, +0.5, +0.5, -0.5, 4.0, 15.0)
-        glMatrixMode(GL_MODELVIEW)
+        self.funcs.glMatrixMode(GL.GL_PROJECTION)
+        self.funcs.glLoadIdentity()
+        self.funcs.glOrtho(-0.5, +0.5, +0.5, -0.5, 4.0, 15.0)
+        self.funcs.glMatrixMode(GL.GL_MODELVIEW)
 
     def mousePressEvent(self, event):
-        self.lastPos = QtCore.QPoint(event.pos())
+        self.lastPos = event.position().toPoint()
 
     def mouseMoveEvent(self, event):
-        dx = event.x() - self.lastPos.x()
-        dy = event.y() - self.lastPos.y()
+        pos = event.position().toPoint()
+        dx = pos.x() - self.lastPos.x()
+        dy = pos.y() - self.lastPos.y()
 
-        if event.buttons() & QtCore.Qt.LeftButton:
+        if event.buttons() & Qt.LeftButton:
             self.rotateBy(8 * dy, 8 * dx, 0)
-        elif event.buttons() & QtCore.Qt.RightButton:
+        elif event.buttons() & Qt.RightButton:
             self.rotateBy(8 * dy, 0, 8 * dx)
 
-        self.lastPos = QtCore.QPoint(event.pos())
+        self.lastPos = pos
 
     def mouseReleaseEvent(self, event):
         self.clicked.emit()
 
     def makeObject(self):
-        dlist = glGenLists(1)
-        glNewList(dlist, GL_COMPILE)
+        dlist = self.funcs.glGenLists(1)
+        self.funcs.glNewList(dlist, GL.GL_COMPILE)
 
         for i in range(6):
-            glBindTexture(GL_TEXTURE_2D, self.textures[i])
+            self.textures[i].bind()
 
-            glBegin(GL_QUADS)
+            self.funcs.glBegin(GL.GL_QUADS)
             for j in range(4):
                 tx = {False: 0, True: 1}[j == 0 or j == 3]
                 ty = {False: 0, True: 1}[j == 0 or j == 1]
-                glTexCoord2d(tx, ty)
-                glVertex3d(0.2 * GLWidget.coords[i][j][0],
-                           0.2 * GLWidget.coords[i][j][1],
-                           0.2 * GLWidget.coords[i][j][2])
+                self.funcs.glTexCoord2d(tx, ty)
+                x = 0.2 * GLWidget.coords[i][j][0]
+                y = 0.2 * GLWidget.coords[i][j][1]
+                z = 0.2 * GLWidget.coords[i][j][2]
+                self.funcs.glVertex3d(x, y, z)
 
-            glEnd()
+            self.funcs.glEnd()
 
-        glEndList()
+        self.funcs.glEndList()
         return dlist
 
 
-class Window(QtWidgets.QWidget):
+class Window(QWidget):
     NumRows = 2
     NumColumns = 3
 
     def __init__(self, parent=None):
-        QtWidgets.QWidget.__init__(self, parent)
+        QWidget.__init__(self, parent)
 
-        mainLayout = QtWidgets.QGridLayout()
+        mainLayout = QGridLayout(self)
         self.glWidgets = []
 
         for i in range(Window.NumRows):
@@ -191,26 +210,25 @@ class Window(QtWidgets.QWidget):
             for j in range(Window.NumColumns):
                 self.glWidgets[i].append(None)
 
+        hue_div = (Window.NumRows * Window.NumColumns - 1)
         for i in range(Window.NumRows):
             for j in range(Window.NumColumns):
-                clearColor = QtGui.QColor()
-                clearColor.setHsv(((i * Window.NumColumns) + j) * 255
-                                  / (Window.NumRows * Window.NumColumns - 1),
-                                  255, 63)
-
-                self.glWidgets[i][j] = GLWidget(self, self.glWidgets[0][0])
-                self.glWidgets[i][j].setClearColor(clearColor)
-                self.glWidgets[i][j].rotateBy(+42 * 16, +42 * 16, -21 * 16)
-                mainLayout.addWidget(self.glWidgets[i][j], i, j)
+                clearColor = QColor()
+                hue = ((i * Window.NumColumns) + j) * 255 / hue_div
+                clearColor.setHsv(hue, 255, 63)
 
-                self.glWidgets[i][j].clicked.connect(self.setCurrentGlWidget)
-                qApp.lastWindowClosed.connect(self.glWidgets[i][j].freeGLResources)
+                glw = GLWidget(self)
+                self.glWidgets[i][j] = glw
+                glw.setClearColor(clearColor)
+                glw.rotateBy(+42 * 16, +42 * 16, -21 * 16)
+                mainLayout.addWidget(glw, i, j)
 
-        self.setLayout(mainLayout)
+                glw.clicked.connect(self.setCurrentGlWidget)
+                qApp.lastWindowClosed.connect(glw.freeGLResources)
 
         self.currentGlWidget = self.glWidgets[0][0]
 
-        timer = QtCore.QTimer(self)
+        timer = QTimer(self)
         timer.timeout.connect(self.rotateOneStep)
         timer.start(20)
 
@@ -225,7 +243,7 @@ class Window(QtWidgets.QWidget):
 
 
 if __name__ == "__main__":
-    app = QtWidgets.QApplication(sys.argv)
+    app = QApplication(sys.argv)
     window = Window()
     window.show()
     sys.exit(app.exec())