Modernize Mesa library

.appveyor.yml

@@ -43,6 +43,8 @@ environment:
 
 before_build:
   - ps: if($env:qtbin.contains('_64')) { $env:BITS=64 } else { $env:BITS=32 }
+  - ps: if($env:qtbin.contains('_64')) { $env:PKGARCH="x64" } else { $env:PKGARCH="x86" }
+  - ps: if($env:qtbin.contains('_64')) { $env:cmake_args:="-A x64" }
   - ps: if($env:qtver.contains('6.')) { $env:SSL="OpenSSL-" } else { $env:SSL="OpenSSL-1-" }
   - set PUBLISH_BINARY=false
   - set USE_EXT_LIBGLES=false
@@ -80,6 +82,7 @@ after_test:
   - if [%PUBLISH_BINARY%]==[true] cmake --build c:\stellarium\build-%qtver%-%qtbin%\ --config %configuration% --target install
   - if [%USE_EXT_LIBGLES%]==[true] appveyor DownloadFile https://github.com/Stellarium/stellarium-data/releases/download/qt-5.6/libGLES-Win%BITS%.zip -FileName c:\stellarium\build-%qtver%-%qtbin%\libGLES.zip
   - if [%USE_EXT_LIBGLES%]==[true] 7z e c:\stellarium\build-%qtver%-%qtbin%\libGLES.zip -aoa -oc:\stellarium-%qtver%-%qtbin%\qtstuff
+  - if [%PUBLISH_BINARY%]==[true] appveyor DownloadFile https://github.com/Stellarium/stellarium-data/releases/download/mesa-win-20.1.8/opengl32sw-%PKGARCH%.dll -FileName c:\stellarium-%qtver%-%qtbin%\qtstuff\opengl32sw.dll
   - if [%PUBLISH_BINARY%]==[true] cmake --build c:\stellarium\build-%qtver%-%qtbin%\ --config %configuration% --target stellarium-installer
   - if [%USE_EXTRA_EXE%]==[true] cmake --build c:\stellarium\build-%qtver%-%qtbin%\ --config %configuration% --target stellarium-patch-installer
   - if [%PUBLISH_BINARY%]==[true] cd c:\stellarium\installers

guide/ch_advanced_use.tex

@@ -453,6 +453,38 @@ \subsubsection{NMEA Device}
 hardware and other settings, e.g. real GPS sensor or network and WiFi
 detection.\footnote{\url{https://support.microsoft.com/en-us/windows/windows-location-service-and-privacy-3a8eee0a-5b0b-dc07-eede-2a5ca1c49088}}
 
+
+\subsection{Modernized MESA3D libraries (Software OpenGL on Windows)}
+\label{sec:ExtraData:Mesa}
+
+Stellarium uses hardware-accelerated OpenGL for rendering. On very old Windows systems without dedicated graphics hardware, 
+or in special circumstances like virtual machines, hardware accelerated graphics may not be available, 
+and the \program{Mesa3D} software implementation of OpenGL is used. This can also be forced by the command-line option \command{-\/-mesa-mode}. 
+Rendering the graphics without hardware acceleration is of course much slower than accelerated graphics, but it's surely better than nothing.
+
+Qt's default Mesa library (Mesa 11) provides support for OpenGL~3.0 only. This prevents users of all versions from applying dithering in Mesa mode. 
+Also the \program{ShowMySky} skylight model (see section~\ref{sec:skylight:ShowMySky}) is then not available.
+
+We have replaced\newFeature{23.4} this by a version of Mesa~20 compiled by Federico Dossena\footnote{\url{https://fdossena.com/?p=mesa/index.frag}} which appears to be even a bit faster.
+
+The \program{Mesa3D} project \footnote{\url{https://www.mesa3d.org/}} meanwhile (2023) provides at least OpenGL~4.5. 
+If you wish to use more ``up to date'' precompiled binaries and have Administrator privileges on your Windows system, 
+you can replace this library using the following steps to install inofficial builds\footnote{\url{https://github.com/pal1000/mesa-dist-win/}}. 
+Note however that after this upgrade, the program runs with considerably ($\approx$35\%?) lower framerate. 
+You must decide whether this is really beneficial in your situation. The libraries don't provide any additional graphics features that Stellarium makes use of.
+
+\begin{itemize}
+\item Download the latest ``release-msvc'' package as you need from \url{https://github.com/pal1000/mesa-dist-win/releases} and unpack it somewhere.
+\item Copy \file{(x86|x64)/{libglapi.dll,libgallium\_wgl.dll,opengl32.dll}} to where the executable \file{stellarium.exe} is.
+\item Delete the existing \file{opengl32sw.dll}
+\item Rename the just-copied \file{opengl32.dll} to \file{opengl32sw.dll}.
+\end{itemize}
+
+\noindent Now running Stellarium in Mesa mode (with link from program menu or command line) should report to provide OpenGL~4.5.
+
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \chapter{Command Line Options}
 %\label{command-line-options}
 \label{sec:CommandLineOptions}
@@ -474,7 +506,7 @@ \chapter{Command Line Options}
 
 For example, using the option \texttt{-c\ my\_config.ini} would resolve to the file 
 \file{\textless{}user\ directory\textgreater{}/my\_config.ini} whereas 
-\file{-c\ ./my\_config.ini} can be used to explicitly say the file
+\file{-c\ ./my\_config.ini} can be used to explicitly point to the file
 \file{my\_config.ini} in the current working directory.\\
 -\/-log-file or -l   & log file name     & Specify the log file name. The default value is \file{log.txt}.
 
@@ -484,7 +516,7 @@ \chapter{Command Line Options}
                                     Note: The old configuration file will be overwritten. \\\midrule
 -\/-user-dir         & path       & Specify the user data directory. \\
 -\/-screenshot-dir   & path       & Specify the directory to which screenshots will be saved. \\\midrule
--\/-full-screen      & yes or no  & Over-rides the full screen setting in the config file. \\\midrule
+-\/-full-screen      & yes or no  & Overrides the full screen setting in the config file. \\\midrule
 -\/-home-planet      & planet     & Specify observer planet (English name). \\
 -\/-longitude        & longitude  & Specify latitude, e.g. +53d58'16.65" \\
 -\/-latitude         & latitude   & Specify longitude, e.g. -1d4'27.48" \\
@@ -509,7 +541,6 @@ \chapter{Command Line Options}
 -\/-angle-d3d11      & {[}none{]} & Force use Direct3D 11 for ANGLE OpenGL ES2 rendering engine.\footnotemark[1]\footnotemark[3]\\
 -\/-angle-warp       & {[}none{]} & Force use the Direct3D 11 software rasterizer for ANGLE OpenGL ES2 rendering engine.\footnotemark[1]\footnotemark[3]\\
 -\/-mesa-mode or -m  & {[}none{]} & Use MESA as software OpenGL rendering engine.\footnotemark[1]\\
--\/-safe-mode or -s  & {[}none{]} & Synonymous to -\/-mesa-mode.\footnotemark[1]\\
 -\/-single-buffer    & {[}none{]} & Use single-buffering. This reportedly avoids screen blanking problems with some Intel GPUs. \\
 -\/-opengl-compat or -C & {[}none{]} & Request OpenGL 3.3 Compatibility Profile. Might fix graphics problems in some driver configurations.\\
 \bottomrule

src/CLIProcessor.cpp

@@ -36,12 +36,7 @@
 void CLIProcessor::parseCLIArgsPreQApp(const QStringList argList)
 {
 #ifdef Q_OS_WIN
-	if (argsGetOption(argList, "-s", "--safe-mode"))
-	{
-		qDebug() << "DEPRECATION NOTE: --safe-mode given on command line. Use --mesa-mode instead!";
-		qputenv("QT_OPENGL", "software");
-	}
-
+    #if QT_VERSION < QT_VERSION_CHECK(6,0,0)
 	if (argsGetOption(argList, "-a", "--angle-mode"))
 		qputenv("QT_OPENGL", "angle");
 
@@ -60,8 +55,15 @@ void CLIProcessor::parseCLIArgsPreQApp(const QStringList argList)
 		qputenv("QT_OPENGL", "angle");
 		qputenv("QT_ANGLE_PLATFORM", "warp");
 	}
+    #endif
 	if (argsGetOption(argList, "-m", "--mesa-mode"))
+	{
 		qputenv("QT_OPENGL", "software");
+		qputenv("MESA_GL_VERSION_OVERRIDE", "3.3"); // The Mesa 20.1.8 library reports providing 3.1 only. This does the trick for us.
+		// These prepare using current Mesa3D libraries, should the user install them. Else the vars are harmless.
+		qputenv("QT_OPENGL_DLL", "opengl32sw.dll");
+		qputenv("GALLIUM_DRIVER", "llvmpipe");
+	}
 #endif
 	// Override user dir. This must be made via environment variable, else an empty user dir is created before resetting (GH:#3079)
 	try
@@ -131,12 +133,13 @@ void CLIProcessor::parseCLIArgsPreConfig(const QStringList& argList)
 		          << "--multires-image        : With filename / URL argument, specify a\n"
 			  << "                          multi-resolution image to load\n"
 #ifdef Q_OS_WIN
+			  #if QT_VERSION < QT_VERSION_CHECK(6,0,0)
 			  << "--angle-mode (or -a)    : Use ANGLE as OpenGL ES2 rendering engine (autodetect driver)\n"
 			  << "--angle-d3d9 (or -9)    : Force use Direct3D 9 for ANGLE OpenGL ES2 rendering engine\n"
 			  << "--angle-d3d11           : Force use Direct3D 11 for ANGLE OpenGL ES2 rendering engine\n"
 			  << "--angle-warp            : Force use the Direct3D 11 software rasterizer for ANGLE OpenGL ES2 rendering engine\n"
+			  #endif
 			  << "--mesa-mode (or -m)     : Use MESA as software OpenGL rendering engine\n"
-			  << "--safe-mode (or -s)     : DEPRECATED! Synonymous to --mesa-mode \n"
 			  #ifdef ENABLE_SPOUT
 			  << "--spout (or -S) <sky|all> : Act as SPOUT sender (Sky only/including GUI)\n"
 			  << "--spout-name <name>     : Set particular name for SPOUT sender.\n"

src/core/StelTexture.cpp

@@ -134,9 +134,27 @@ StelTexture::GLData StelTexture::loadFromPath(const QString &path, const int dec
 {
 	try
 	{
-		return imageToGLData(QImage(path), decimateBy);
+		QImageReader imgReader(path);
+		QImage img = imgReader.read();
+		if (img.isNull())
+		{
+			QImageReader::ImageReaderError error=imgReader.error();
+			qCritical() << "Error reading image file " << path << ":" << imgReader.errorString();
+
+			if (error==QImageReader::InvalidDataError)
+				qCritical() << "This may also indicate an out-of-memory error.";
+		}
+		return imageToGLData(img, decimateBy);
+	}
+	catch(std::bad_alloc& ex) //this catches out-of-memory errors from file conversion
+	{
+		qCritical()<<"Failed loading texture from"<<path<<"error:"<<ex.what();
+		qCritical() << "Try higher value for config.ini:[astro]/nebula_texture_decimation";
+		GLData ret;
+		ret.loaderError = ex.what();
+		return ret;
 	}
-	catch(std::exception& ex) //this catches out-of-memory errors from file conversion
+	catch(std::exception& ex) //this catches other errors from file conversion
 	{
 		qCritical()<<"Failed loading texture from"<<path<<"error:"<<ex.what();
 		GLData ret;

src/core/modules/Landscape.cpp

@@ -550,6 +550,8 @@ void LandscapeOldStyle::load(const QSettings& landscapeIni, const QString& lands
 		// if that query is not going to be prevented by the polygon that already has been loaded at that point...
 		if ( (!horizonPolygon) && calibrated ) { // for uncalibrated landscapes the texture is currently never queried, so no need to store.
 			QImage *image = new QImage(texturePath);
+			if (image->isNull())
+				qWarning() << "Null image (out of memory!) in Landscape!";
 			sidesImages.append(image); // indices identical to those in sideTexs
 			memorySize+=(image->sizeInBytes());
 		}
@@ -1567,6 +1569,8 @@ void LandscapeFisheye::create(const QString _name, float _texturefov, const QStr
 	{
 		mapImage = new QImage(_maptex);
 		memorySize+=(mapImage->sizeInBytes());
+		if (mapImage->isNull())
+			qWarning() << "Null image in Landscape" << _name << "- cannot load" << _maptex;
 	}
 	mapTex = texMan.createTexture(_maptex, StelTexture::StelTextureParams(true));
 	memorySize+=mapTex->getGlSize();
@@ -1852,6 +1856,8 @@ void LandscapeSpherical::create(const QString _name, const QString& _maptex, con
 	{
 		mapImage = new QImage(_maptex);
 		memorySize+=(mapImage->sizeInBytes());
+		if (mapImage->isNull())
+			qWarning() << "Null image in Landscape" << _name << "- cannot load" << _maptex;
 	}
 
 	auto& gl = *QOpenGLContext::currentContext()->functions();