Fix OpenGL driver for Qt 6

.github/workflows/build.yml

@@ -3,10 +3,8 @@ name: build
 on: [push]
 
 jobs:
-  linux:
-
+  linux-qmake:
     runs-on: ubuntu-latest
-
     steps:
     - uses: actions/checkout@v1
     - name: prerequisites
@@ -17,9 +15,7 @@ jobs:
       run: make
 
   linux-cmake-deepzoom:
-
     runs-on: ubuntu-latest
-
     steps:
     - uses: actions/checkout@v1
     - name: prerequisites
@@ -29,10 +25,19 @@ jobs:
     - name: make
       run: cd cbuild; make
 
-  mac:
+  linux-cmake-opengl:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v1
+    - name: prerequisites
+      run: sudo apt update && sudo apt install build-essential qt6-base-dev qt6-tools-dev qt6-tools-dev-tools qt6-l10n-tools linguist-qt6 libgl1-mesa-dev freeglut3-dev
+    - name: cmake
+      run: mkdir cbuild; cd cbuild; cmake -DOPENGL=ON ..
+    - name: make
+      run: cd cbuild; make
 
+  mac-qmake:
     runs-on: macos-latest
-
     steps:
     - uses: actions/checkout@v1
     - name: install-qt
@@ -45,9 +50,7 @@ jobs:
       run: make
 
   mac-cmake:
-
     runs-on: macos-latest
-
     steps:
     - uses: actions/checkout@v1
     - name: install-qt

CMakeLists.txt

@@ -53,6 +53,18 @@
 #   -DDEEPZOOM=ON
 #
 #   on the cmake command line.
+#
+# * Alternatively, it is possible to build XaoS with the OpenGL driver. For this, you may need
+#   additional libraries:
+#
+#   - freeglut3-dev
+#
+#   Add
+#
+#   -DOPENGL=ON
+#
+#   on the cmake command line to enable the driver.
+
 
 ###########################################################################
 
@@ -66,17 +78,25 @@ cmake_minimum_required(VERSION 3.14.0)
 project(XaoS)
 
 option(DEEPZOOM "Use 128-bit float for deep zoom" OFF)
+option(OPENGL "Use OpenGL" OFF)
+
 if(DEEPZOOM)
    add_definitions(-DUSE_FLOAT128) # may be unsupported on Mac, unless gcc/g++ is used
 else(DEEPZOOM)
    add_definitions(-DUSE_LONG_DOUBLE)
 endif(DEEPZOOM)
 
+if(OPENGL)
+   add_definitions(-DUSE_OPENGL)
+endif(OPENGL)
+
+# general definitions
 add_definitions(-DUSE_SFFE -DSFFE_CMPLX_GSL)
 
 # resolve symbolic links
 set(CMAKE_FIND_PACKAGE_RESOLVE_SYMLINKS TRUE)
 
+# by default, build a release (a non-debug executable)
 if(NOT CMAKE_BUILD_TYPE)
    set_property(CACHE CMAKE_BUILD_TYPE PROPERTY VALUE Release)
 endif(NOT CMAKE_BUILD_TYPE)
@@ -93,6 +113,13 @@ set(CMAKE_AUTORCC ON)
 find_package(QT NAMES Qt6 COMPONENTS Widgets PrintSupport REQUIRED)
 find_package(Qt6 COMPONENTS Widgets PrintSupport REQUIRED)
 
+if(OPENGL)
+   find_package(QT NAMES Qt6 COMPONENTS OpenGL OpenGLWidgets REQUIRED)
+   find_package(Qt6 COMPONENTS OpenGL OpenGLWidgets REQUIRED)
+   find_package(GLUT REQUIRED)
+   find_package(OpenGL REQUIRED)
+endif(OPENGL)
+
 # OS specific stuff
 # on macOS the QT libraries are usually not installed into the system library folders
 if (${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
@@ -139,11 +166,14 @@ add_executable(XaoS MACOSX_BUNDLE
    XaoS.qrc
 )
 
-# Link
+# link libraries
 target_link_libraries(XaoS Qt6::Widgets Qt6::PrintSupport)
 if(DEEPZOOM)
-target_link_libraries(XaoS quadmath)
+   target_link_libraries(XaoS quadmath)
 endif(DEEPZOOM)
+if(OPENGL)
+   target_link_libraries(XaoS Qt6::OpenGL Qt6::OpenGLWidgets)
+endif(OPENGL)
 
 # install bundle
 install(TARGETS XaoS DESTINATION bin)

src/engine/3d.cpp

@@ -1,4 +1,4 @@
-#include "config.h"
+#include "config.h"
 #include <cstdlib>
 #include <cstdio> /*for NULL */
 #include <cmath>

src/ui-hlp/autod.h

@@ -1,4 +1,4 @@
-#ifndef UNSUPPORTED
+#ifndef UNSUPPORTED
 static inline int look1(uih_context *context, int x, int y, int range, int max)
 {
     cpixel_t *vbuff;

src/ui-hlp/autopilot.cpp

@@ -1,4 +1,3 @@
-
 /*
  *     XaoS, a fast portable realtime fractal zoomer
  *                  Copyright (C) 1996,1997 by

src/ui-hlp/autopilot.h

@@ -1,4 +1,3 @@
-
 /*
  *     XaoS, a fast portable realtime fractal zoomer
  *                  Copyright (C) 1996,1997 by

src/ui-hlp/messg.cpp

@@ -1,4 +1,4 @@
-#include <cstdlib>
+#include <cstdlib>
 #include <cstring>
 #include "filter.h"
 #include "fractal.h"

src/ui-hlp/play.cpp

@@ -1,4 +1,4 @@
-#include <climits>
+#include <climits>
 #include <cstdlib>
 #include <cstring>
 #include "config.h"

src/ui-hlp/play.h

@@ -1,4 +1,4 @@
-#ifndef PLAY_H
+#ifndef PLAY_H
 #define PLAY_H
 struct keyword {
     char *name;

src/ui-hlp/playtext.cpp

@@ -1,4 +1,4 @@
-#include <cstdlib>
+#include <cstdlib>
 
 #include "config.h"
 #include "filter.h"

src/ui-hlp/render.cpp

@@ -1,4 +1,3 @@
-
 #include <cstring>
 #include <cmath>
 #include <cstdlib>

src/ui-hlp/save.cpp

@@ -1,4 +1,4 @@
-#define __USE_MINGW_ANSI_STDIO 1 // for long double support on Windows
+#define __USE_MINGW_ANSI_STDIO 1 // for long double support on Windows
 #include <cstdio>
 #include <climits>
 #include <cstring>

src/ui-hlp/wstack.cpp

@@ -1,4 +1,4 @@
-#include <cstdlib>
+#include <cstdlib>
 #include <cstring>
 #include <cassert>
 

src/ui/fractalwidget.cpp

@@ -1,4 +1,4 @@
-#include "fractalwidget.h"
+#include "fractalwidget.h"
 
 #include <QtGui>
 #ifdef USE_OPENGL
@@ -28,9 +28,14 @@ void FractalWidget::paintGL()
     if (m_image) {
         QImage *qimage =
             reinterpret_cast<QImage **>(m_image->data)[m_image->currimage];
-        QImage glimage = QGLWidget::convertToGLFormat(*qimage);
-        glDrawPixels(glimage.width(), glimage.height(), GL_RGBA,
-                     GL_UNSIGNED_BYTE, glimage.bits());
+        // QImage glimage = QGLWidget::convertToOpenGLFormat(*qimage);
+        // glDrawPixels(glimage.width(), glimage.height(), GL_RGBA,
+        //              GL_UNSIGNED_BYTE, glimage.bits());
+        // For some reason, Qt 6 requires mirroring the image and using another color space.
+        // The old convertToOpenGLFormat is no longer supported in Qt 6.
+        QImage mirrored = qimage->mirrored(false, true);
+        glDrawPixels(qimage->width(), qimage->height(), GL_BGRA_EXT,
+                  GL_UNSIGNED_BYTE, mirrored.bits());
     }
 }
 

src/ui/fractalwidget.h

@@ -1,16 +1,16 @@
-#ifndef FRACTALWIDGET_H
+#ifndef FRACTALWIDGET_H
 #define FRACTALWIDGET_H
 
 #include "config.h"
 #include <QWidget>
 #ifdef USE_OPENGL
-#include <QGLWidget>
+#include <QOpenGLWidget>
 #endif
 class QImage;
 class QPoint;
 
 #ifdef USE_OPENGL
-class FractalWidget : public QGLWidget
+class FractalWidget : public QOpenGLWidget
 #else
 class FractalWidget : public QWidget
 #endif

src/ui/image_qt.cpp

@@ -1,4 +1,4 @@
-#include <QtWidgets>
+#include <QtWidgets>
 #include "config.h"
 #include "filter.h"
 #include "grlib.h"

src/ui/mainwindow.cpp

@@ -1,4 +1,4 @@
-#include <QtWidgets>
+#include <QtWidgets>
 #include <cassert>
 #include <QTimer>
 #include <iostream>

src/ui/mainwindow.h

@@ -1,4 +1,4 @@
-#ifndef MAINWINDOW_H
+#ifndef MAINWINDOW_H
 #define MAINWINDOW_H
 
 #include <QMainWindow>